If you wish to International: powder injection moulding. · e-mail: [email protected] cover...

Vol 4 No 1 M

AR

CH

2010 P

owder Injection M

oulding International

International: powder injection moulding.� If you wish to

produce complex ceramic and metal products using the PIM process, then come to the leading inter-

national specialists in this field: ARBURG. For you, we have the appropriate ALLROUNDER machine

technology and the required know-how from our PIM laboratory. With our expertise, you will be able

to manufacture efficiently and to the highest quality, prepare material, injection-mould components,

debind and sinter - finished! You want to find out more about PIM processing? Simply talk to us!

ww

w.a

rbur

g.co

m

ARBURG GmbH + Co KGPostfach 11 09 · 72286 Lossburg/GermanyTel.: +49 (0) 74 46 33-0Fax: +49 (0) 74 46 33 33 65e-mail: [email protected]

cover spread.indd 1 3/5/2010 11:30:49 AM

March 2010 Powder Injection Moulding International �Vol. 4 No. 1

For the metal, ceramic and carbide injection moulding industries

Publisher & editorial officesInovar Communications Ltd 2 The Rural Enterprise CentreBattlefield Enterprise ParkShrewsbury SY1 3FE, United Kingdom Tel: +44 (0)1743 454990Fax: +44 (0)1743 469909Email: [email protected]: www.inovar-communications.com

Managing Director and Editor Nick Williams Tel: +44 (0)1743 454991 Fax: +44 (0)1743 469909Email: [email protected]

Publishing DirectorPaul Whittaker Tel: +44 (0)1743 454992 Fax: +44 (0)1743 469909Email: [email protected] Consulting Editors Professor Randall M. GermanAssociate Dean of Engineering, Professor of Mechanical Engineering, San Diego State University, USA

Dr Yoshiyuki KatoDirector, Epson Atmix Corporation, Japan

Dr Professor Frank PetzoldtDeputy Director, Fraunhofer IFAM, Bremen, Germany

Bernard Williams Consultant, Shrewsbury, UK

Advertising Jon Craxford, Advertising Manager Tel: +44 (0) 207 1939 749 Fax: +44 (0) 1242 291 482 E-mail: [email protected]

SubscriptionsPowder Injection Moulding International is published on a quarterly basis. The annual subscription charge for four issues is £95.00 including shipping. Rates in € and US$ are available on application.

Accuracy of contentsWhilst every effort has been made to ensure the accuracy of the information in this publication, the publisher accepts no responsibility for errors or omissions or for any consequences arising there from. Inovar Communications Ltd cannot be held responsible for views or claims expressed by contributors or advertisers, which are not necessarily those of the publisher.

Advertisements Although all advertising material is expected to conform to ethical standards, inclusion in this publication does not constitute a guarantee or endorsement of the quality or value of such product or of the claims made by its manufacturer.

Reproduction, storage and usage Single photocopies of articles may be made for personal use in accordance with national copyright laws. Permission of the publisher and payment of fees may be required for all other photocopying.

All rights reserved. Except as outlined above, no part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, photocopying or otherwise, without prior permission of the publisher and copyright owner.

Design and productionInovar Communications Ltd Printed byCambrian Printers, Aberystwyth, United Kingdom

ISSN 1753-1497

Vol. 4, No. 1 March 2010

© 2010 Inovar Communications Ltd.

Cover image This six axis robot gripper is picking two parts during the moulding operation (Courtesy Parmaco Metal Injection Molding AG, Switzerland)

Fresh signs of growth allow for optimism

Welcome to our first issue of 2010. After a challenging 2009 all the signs are that our industry is starting to grow again. The recent 2010 forecast from the Japan Powder Metallurgy Association (see page 10) suggests that this year’s sales will increase to beyond 2008’s levels after a significant dip last year.

A number of parts and materials suppliers are also indicating that they are seeing an increase in order volumes, along with higher levels of interest. Discussions at the forthcoming MIM2010 conference in Long Beach, USA, will certainly shed more light on the industry’s situation. A full report will be published in the June 2010 issue.

Highlights from this feature packed 72 page issue include reports on developments and opportunities for 2-component powder injection moulding (2C-PIM) and the latest innovations at Swiss MIM producer Paramco Metal Injection Molding AG. We also present a unique insight into the history, current status and outlook for Korea’s dynamic PIM industry.

Technical papers are regarded as an essential aspect of Powder Injection Moulding International. In this issue we are delighted to be able to present three papers from some of the most highly regarded researchers and research centres in China, Japan and Spain.

Nick WilliamsManaging Director and Editor

March 2010 Front Section.indd 1 3/5/2010 1:37:56 PM

SPECIAL FURNACE EQUIPMENT IS OUR BUSINESS

CREMER Thermoprozessanlagen GmbH www.cremer-furnace.comAuf dem Flabig 10 D-52355 Düren - Konzendorf www.cremer-ofenbau.de

Tel.: +49 2421 61021 Fax: + 49 2421 63735 [email protected]

- Sintering for PM as Low-, Medium- and High-Temp.

- MIM-Applications Debinding and Sintering Equipment

- Sinter-Forging

- Powder Reduction

- Calzination

- Tungsten-Carburisation

- Graphite insulated & heated up to 2.200°C

- Rotary-hearth Furnaces up to 1.750°C in protective gas atmosphere

- Drum-type Rotary Furnaces for reduction & calzination application

- Multi-tube Powder Reduction Furnaces (for tungsten & molybdenum powders)

- Annealing

- Sintering of Aluminum

- Protective Gas Generators

- Computer-supported Process Visualisation

- Maintenance Service and Spare parts

Visit us at

EURO PM2009 Stand 81/83

Visit us at

CERAMITEC 2009Stand B6/101

ISF COVER.indd 1 02/09/2009 11:51:48

Visit us at

General cremer ad.indd 1 3/5/2010 10:16:03 AM

Powder Injection Moulding International March 2010� Vol. 4 No. 1

273-PROD-PUB Microneex-7.eps 17/02/10 15:58:49



March 2010

In this issue Technical papers

Regular features

50 Design and Manufacture of Gears with a Skin-Core Structure by Metal Co-Injection Moulding

Hao He, Yimin Li, Pan Liu, Jianguang Zhang

55 A Case Study on Computational Fluid Dynamics Analysis of Micro-MIM Products

Ian Andrews, Kazuaki Nishiyabu and Shigeo Tanaka

67 Influence of Particle Size Distribution and Chemical Composition of the Powder on Final Properties of Inconel 718 Fabricated by Metal Injection Moulding (MIM)

J. M. Contreras, A. Jiménez-Morales and J. M. Torralba

21 Multifunctional parts by two-component Powder Injection Moulding (2C-PIM) The ability to manufacture components in one step using two different materials is opening up a world of opportunities for the powder injection moulding industry. Dr. Frank Petzoldt looks at the development of this technology to-date and outlines the challenges.

29 Parmaco Metal Injection Molding AG: High tech MIM manufacturing in a Swiss rural retreat Fischingen, Switzerland, is the home of Parmaco Metal Injection Molding AG, one of Europe’s leading and most innovative MIM producers since 1992. Bernard Williams reports on his recent visit for PIM International.

35 PIM in Korea: A review of technology development, production and research Thanks to South Korea’s status as one of the fastest growing economies in the world, the country’s PIM industry has become an important force in both component production and R&D. Dr. Seong-Jin Park and Dr. Yong-Jin Kim present a review of the development of PIM in this, the largest of Asia’s ‘Tiger’ economies.

43 Looking into a MIM furnace: Understanding debinding and sintering using mass spectrometry

By coupling a mass spectrometer to the exhaust system of an industrial scale furnace, researchers have gained a detailed insight into the changes and reactions that take place during the critical debinding and sintering stages of the MIM process. Thomas Hartwig and Renan Schroeder report their initial findings.

5 Industry news

48 Global PIM patents

72 Events guide, Advertisers’ index

9 31 433924

273-PROD-PUB Microneex-7.eps 17/02/10 15:58:49



Catamold®

Imagination is the only limit.

BASF SEGBU Inorganic Specialties Powder Injection MoldingG-CAS/BP – J51367056 Ludwigshafen, GermanyPhone: +49 621 60 52835E-mail: [email protected]: www.basf.de/catamold

Discover the amazing possibilities of metal and ceramic components manufacturing using Power Injection Molding with Catamold® and BASF.

With Catamold®, conventional injection molding machines can be used to produce geometrically demanding components economically. You can do injection molding of metal and ceramic feedstock as easily as plastic. And this opens up new means of producing complex components that provide economic and technical benefi ts in sectors ranging from Automotive, Consumer Products, and Mechanical Engineering to Medical Products and Communications/Electronics.

Take advantage of the new diversity in Powder Injection Molding with Catamold®.Get in touch with us – we’ll be glad to help you on the road to success.

®= registered trademark of BASF SE

[ Catamold® – Inject your ideas ]

892_Catamold_Anzeige_210x297_RZ_02.indd 1 28.01.2009 11:10:20 UhrMarch 2010 Front Section.indd 4 3/5/2010 1:38:20 PM


Industry NewsTo submit news for inclusion in Powder Injection Moulding International please contact Nick Williams [email protected]

Industry News

Catamold®

Imagination is the only limit.

BASF SEGBU Inorganic Specialties Powder Injection MoldingG-CAS/BP – J51367056 Ludwigshafen, GermanyPhone: +49 621 60 52835E-mail: [email protected]: www.basf.de/catamold

Discover the amazing possibilities of metal and ceramic components manufacturing using Power Injection Molding with Catamold® and BASF.

With Catamold®, conventional injection molding machines can be used to produce geometrically demanding components economically. You can do injection molding of metal and ceramic feedstock as easily as plastic. And this opens up new means of producing complex components that provide economic and technical benefi ts in sectors ranging from Automotive, Consumer Products, and Mechanical Engineering to Medical Products and Communications/Electronics.

Take advantage of the new diversity in Powder Injection Molding with Catamold®.Get in touch with us – we’ll be glad to help you on the road to success.

®= registered trademark of BASF SE

[ Catamold® – Inject your ideas ]

892_Catamold_Anzeige_210x297_RZ_02.indd 1 28.01.2009 11:10:20 Uhr

Ceramco, Inc. purchases high pressure injection moulding line from Advanced Cerametrics, Inc.Ceramco, Inc., located in the town of Center Conway, New Hampshire, USA, has purchased a high pressure ceramic injection moulding (HPIM) production line and related process technology from Advanced Cerametrics, Inc. (ACI), based in Lambertville, New Jersey, USA.

Mr. Thomas Henriksen, President of Ceramco, Inc. told PIM International, “The purchase of this long established, superior technology is a perfect adjunct to Ceramco’s existing low pressure injection moulding product line (LPIM). The new capability will expand Ceram-co’s already broad product range, providing much higher volume capacity, higher tolerance production and, most importantly, the ability to make much thicker walls and cross sections.” Bud Cass, Board Chairman of Advanced Cerametrics, Inc. noted that, “The transfer of this technology to Ceramco is a natural progression of our long standing relationship with them. ACI is focusing on its ceramic fibre technology and sees Ceramco

as the ideal manufacturer to transfer this technology to by continuing to offer HPIM products to ACI’s existing customers in addition to the new opportunities afforded Ceramco with this capability. We are pleased to place our customers in Ceramco’s hands, because we are certain that they will be given the attention and quality they have become accustomed to with ACI.”

The production line is being set up in 3,500 square feet of unused warehouse space at Ceramco’s New Hampshire headquarters and will involve the immediate hiring of 6-10 new employees, engineers and supervi-sory personnel with more being added as the new HPIM products are integrated into Ceramco’s established LPIM business. The transfer of this production line frees up about

4,500 square feet of controlled environ-ment space at ACI, which will be used to expand ACI’s piezoelectric ceramic fiber Energy Harvesting product line and electronic assembly operations.

www.ceramcoceramics.com

This prototype part is used in a homeland security application and is made of fully-dense, 96% aluminum oxide. It has 23 internal threaded holes and does not require any machining in its manufacture

New Standard planned for MIM titanium alloys used in medical applicationsThe F04.12 Sub-committee on Metallurgical Materials at ASTM International (USA) has initiated a new work item, ASTM WK26721, aimed at establishing standard specifica-tions for metal injection moulded (MIM) Ti-6Al-4V net or near-net shape parts for surgical implants.

ASTM reports that a draft standard is under develop-ment and the new standard will aid MIM manufacturers as well as medical device companies. The MIM Ti alloy standard is meant to be complimentary to the ASTM F136 or ASTM F1472 Standards. Technical contact for this new work item is Matthias Scharvogel.

Email at ASTM: [email protected]



Industry News

Promoting PIM technology in AustraliaPowder injection moulding (PIM) is relatively new in Australia with only one company known to be actively producing PIM components, Ceramet, based in Ballarat. Ceramet is said to be exporting the vast majority of its production. Now, Arnold Rowntree at the Swinburne’s Centre for New Manufacturing (part of the Swinburne University of Technology, Melbourne) has taken up the challenge of promoting PIM technology to Australian manufacturers and end-users. Rowntree told PIM International that a demonstration project has been arranged between Swinburne University of Technology and a local plastic moulder in Melbourne with BASF providing samples of its Catamold feedstock based on FN08 low alloy steel.

Rowntree stated that other partners are being approached as needed, for example a local metrology equipment and software supplier will provide inspection services in return for publicity looking at the green, brown and sintered parts. “These need to be compared with the original CAD design so that the variation inherent in every manufacturing step can be predicted when looking at subsequent jobs that our project participants might wish to bid on. The data is available of course but it feels so much better when you confirm it for yourself and know for sure that you have the necessary skills to achieve a measurable level of quality”, he said.

Swinburne University of Technology has signed a non-disclosure agreement with Kurt Schnepf of KCS Australia which has micro machining and micro moulding capabilities. “Some aspects of KCS’s key capabilities as a moulder and toolmaker will remain confidential under the agreement, but in general the results of the trial will be publicised to encourage the uptake of metal injection moulding (MIM) and ceramic injection moulding (CIM) by other moulders in Australia”, said Rowntree.

“The initial part is said to be a ‘tricky little’ component about 15mm in length with some fine features but it can’t be called micro. Perhaps the next part we do will be smaller and then further commercial projects will lead us in the direction of tiny parts with micro-sized features and tolerances. Micro parts are increasingly being required in interesting materials and we look forward to developing that capability in a sustainable commercial progression” continued Rowntree.

Records of this demonstration project will be main-tained at www.smallmouldedparts.com and the metrology results will first be published there as they are released. “We look forward to keeping PIM International informed on our progress” said Rowntree.

In 2008 the Commonwealth Scientific Industrial Research Organisation (CSIRO) developed a cost efficient way to make titanium powders some of which may prove useful in MIM. Rowntree is hoping that the commer-cialisation of this breakthrough could give prospective Australian MIM producers a competitive advantage in the next few years.

www.topmim.com

TOPMIM INTERNATIONAL LIMITED

BRING VALUE TO THE CUSTOMER BY CONTINUOUS IMPROVEMENT

TOPMIM INTERNATIONAL LIMITEDRm 2007, Deep Blue Plaza,

No. 205 Zhaohui Rd, HangzhouZhejiang, China 310010 Tel: 0086-571-56766077

Fax: 0086-571-56766075Email: [email protected]: [email protected]

TOPMIM is a leading Chinese Metal Injection Molding (MIM) producer, supplying high quality components at a competitive price.

Materials include tungsten alloys, 316L stainless steel, Kovar and more.

WWe have deep understanding of MIM, offer tight tolerances and the ability to tailor feedstock to match the necessary physical and chemical requirements.

Our promise: we refund the mold cost if we are not able to accomplish your job, no excuse!



Industry News

Kyocera delivers high temperature ceramic micro-turbine rotors for gas turbines

Kyocera Industrial Ceramics Corp of Vancouver, Washington, USA, recently delivered high-temperature silicon nitride SN-282 rotors to a nationally recognised gas turbine engine (GTE) research and develop-ment laboratory, which is developing a three-kilowatt GTE-powered electrical generator.

Kyocera’s SN-282 ceramic material is the rotor material of choice

for the manufacturer’s miniature gas turbine engine, due to its exceptional creep resistance at high temperatures and Kyocera’s proven capability to mass-produce ceramic components in complex net shapes for cost-sensitive markets. SN-282’s high-temperature properties allow for a progressive engine design that does not require rotor blades to have embedded cooling-air channels, a structural element that traditionally presents manufacturing complications and dramatically increases production costs.

Additionally, the higher operating temperature permitted by ceramic creates significant gains in thermal efficiency. As a result, Kyocera expects the ceramic-equipped GTE to provide a competitive alternative to the internal-combustion engine. The ceramic-equipped GTE will compete with, or beat, small gasoline engines on fuel economy, while providing the superior longevity and reliability of a gas turbine.

Demand for portable three-kilowatt generators for use in land and air applications is expected to grow significantly over the next 10 years. Kyocera has been providing high quality monolithic ceramic components to the gas turbine engine industry for more than 20 years, with facilities in the United States and Japan.

Kyocera Industrial Ceramics Corporation: Steven Foster, Aerospace Products Email: [email protected]

Microwave sintering company receives NSF AwardCeralink Inc of Troy, New York, has been involved in the development of microwave sintering technology for ceramics for some 10 years.Dr Holly Shulman, President and Chief Technical Officer, reports that the company has been awarded a $150,000 Phase I contract by the National Science Founda-tion (NSF) to develop an ultra-high temperature (>1800°C) microwave sintering process for densifying ceramics for armour and other structural applications. Materials of particular focus are boron carbide and silicon carbide.

www.ceralink.com





Industry News

Parmatech Corporation, one of North America’s leading provider of MIM components, has announced that Parmatech-Proform Corporation (Proform), has acquired a manufac-turing facility in East Providence, Rhode Island. The new facility will serve as Proform’s future headquarters.

Proform was acquired by ATW in 2009 from Morgan Advanced Ceramics specifically to augment and compli-ment Parmatech’s California-based

Parmatech to move its east coast MIM operation to a new facility

MIM operation. Both Parmatech and Proform will focus on MIM component production and secondary MIM opera-tions for the medical, telecommunica-tions, firearms, handtools, semi-conductor and electronic packaging markets. The existence of two separate facilities, states Parmatech, offers these markets significantly enhanced logistical and security benefits.

The 25,000 square foot East Providence facility will be fully opera-

tional by summer 2010. Until then, operations will continue in the current New Bedford location. Peter C. Frost, President of ATW Companies, Inc., stated, “MIM is a very exciting technology which has now established itself as a mainstream metal fabrication technique.

By acquiring Proform and setting them up in their own purpose-built, state-of-the-art facility, we will be in a position to offer not only our award winning technical expertise in MIM, but logistical and redundancy benefits as well.”

Parmatech recently exhibited at the Medical Device & Manufacturing (MD&M) West Expo, February 9-11, 2010, at the Anaheim Convention Center in Anaheim, California, where it promoted its MIM capabilities for the medical sector. The company manu-factures MIM components used in a variety of bariatric and laparoscopic instruments and orthodontics that take advantage of MIM’s miniaturisation and intricate shape capability.

Applications also include sealing and transecting of blood vessels and vein harvesting for bypass surgeries. Highlighted products at this year’s show include the 2008 MPIF Design Competition Grand Prize winning articulation gear, laparoscopic jaw sets and self-ligating orthodontic brackets.

www.parmatech.com

MIM Debind and Sinter Furnacesfor Metal and Ceramic Injection Molded Materials

Over 6000 units built since 1954Over 80 different styles of batch and continuous furnacesfrom 1 cu cm to 28 cu m. Custom sizes available. Testing available in our Applied Technology Centerfurnaces to 2800°CWorldwide Field Service and Spare Parts availablefor all furnace makes and models.

CompetenceVersatilityInnovative

Metal or graphite hotzonesSizes from 0.3–12 cu ft.Pressures from 10-6 torr–750 torrOperates in Vac, Ar, N2,and H2All binders and feedstocks

www.centorr.com/pi

Centorr Vacuum Industries, Inc.55 Northeastern Blvd., Nashua NH Toll free: 800-962-8631

Ph: 603-595-7233 Fax: 603-595-9220 E-mail: [email protected]

Details at

Advances in simulation of micro PIM at the University of FreiburgComplex materials which are strongly deformed remain a computation challenge in the simulation of micro powder injection moulding. Researchers in the Department of Microsystems Engineering (IMTEK) at the University of Freiburg, Germany, report that they have adapted ‘smoothed particle hydrodynamics’ (SPH) to help in the requirements of the micro PIM for both metals and ceramics.

The researchers found that feedstocks for micro PIM possess a significant yield stress effect which could be modelled by means of the viscosity regularisation technique, i.e., the approximation of the yielded and unyielded domains of the material by two different viscosities. Incorporated into the particle based SPH-formalism, the model successfully reproduces an experimental observation of splitting in a channel with a cylindrical obstacle.

The researchers incorporated shear induced powder migration using a diffusive flux model. The simulations could then correctly predict powder migration to regions with the lowest shear rates. For injection moulding into complex geometries the simulations help to predict an accumulation of the solids fraction at convex corners (pointing outside of the cavity) and a depletion at concave corners (pointing inside the cavity).

Contact: David Kauzlaric email: [email protected]


Powder Injection Moulding International March 2010�0 Vol. 4 No. 1

Industry News

The Japan Powder Metallurgy Association (JPMA) recently released figures in its 2009 Annual Report which showed that sales of MIM parts in Japan fell by 11.5% in 2008 to 13.9 billion Yen. The JPMA attributed the decline to the global economic recession and stated that a further fall of some 15% was also expected for 2009.

A survey of the 26 MIM companies operating in Japan indicated that there would be recovery in 2010 with sales reaching 14.3 billion yen. More than 50% of MIM output is based on stainless steel grades with low alloy steels (Fe-Ni) making up a further 23.2%.

The automotive sector remains the largest user of MIM parts in Japan (19.9%) followed by industrial machinery (16%), Information equipment (14.2%) and medical appli-ances (12.4%).

MIM sales set to rebound in Japan after falls in 2008 and 2009

Japanese MIM industry statistics courtesy Japan Powder Metallurgy Association


March 2010 Powder Injection Moulding International ��Vol. 4 No. 1

Industry News

New computer-aided prediction technique for sintering ceramicsResearchers at the Department of Engineering at the University of Leicester in the UK have developed a new technique in the manufacture of ceramics that takes away the traditional ‘trial and error’ approach to manufacture, and instead applies new computer modelling techniques specifically for the sintering part of the process.

Professor Jingzhe Pan stated that the principal aim was to minimise errors during the sintering process. He said, “Predicting change in dimension during sintering is challenging and requires exten-sive data on the material in question. Obtaining the required physical data has been difficult and expensive.

“Our method simply uses density measure-ments of different ceramics during sintering in our computer software that can predict changes in dimensions, even before production begins. This method does not depend on the physical properties of any one ceramic material, it simply uses densi-fication data from a small sample of the material and extrapolates the data, such that it can be applied to larger quantities used in manufacturing. It can thus, be applied to a wide range of ceramics”.

Professor Pan, who has been investigating this process for the last 10 years, added that the system will need to be converted into a more ‘user-friendly’ format for industrial use. Further, the technique will have to be demonstrated in a range of indus-trial products.

Email: [email protected]

Hybridica trade fair looks to increase its appeal with PIM technology Hybridica, the International Trade Fair for the Devel-opment and Manufacture of Hybrid Components, will be held in Munich from November 9-12, 2010.

The organisers of the event, which is being held at the same time as the international trade fair Electronica, state that the show will represent the complete chain for hybrid components - including those produced by the PIM process - covering everything from raw materials, development and prototyping to tool and die manufacturing, produc-tion systems and automation concepts.

“Regardless of the composites, manufacturers are all pursuing the same objective: to take advantage of the respective benefits, reduce mate-rial consumption and weight and integrate more functions or new ones by coming up with intelligent combinations”, says Thomas Rehbein, Deputy Director of the Business Unit for New Technologies at Messe München GmbH.

www.hybridica.de


Powder Injection Moulding International March 2010�� Vol. 4 No. 1

Industry News

New ‘bone-hard’ injection moulded biomaterialScrews used in surgical operations are often made of titanium and usually have to be removed or replaced after a fixed period. A new biomaterial makes this unnecessary, promotes bone growth and is biodegradable.

Football players, skiers, tennis players for example all fear a crucial ligament rupture. If the knee ligaments are damaged the patient usually has to undergo surgery to restore the stability of the joint. In the surgical procedure the torn ligament is replaced by a piece of tendon from the leg, which is fixed to the bone by means of an interferential screw. The problem is that the screws are made of titanium. After a certain time the patient has to undergo a further surgery so that the material can be removed.

Researchers at the Fraunhofer IFAM in Bremen, Germany, have developed a technology that could spare cruciate ligament victims and other bone patients this additional procedure, based on a screw which is biocompatible and also biodegradable over time. “We have modified biomaterials in such a way that they can be formed into robust bioactive and resorbable screws by means of a special injection moulding process”, explains Dr. Philipp Imgrund, Head of the Biomate-rial Technology department at IFAM. “Depending on the composition they biodegrade in 24 months”.

Biodegradable screws made of polylactic acid are already used in the medical field, but they have the disadvantage that when they degrade they can leave holes in the bone. The IFAM researchers have therefore improved the material and developed a mouldable composite made of polylactic acid and hydroxylapatite, a ceramic which is the main constituent of the bone mineral. “This composite possesses a higher proportion of hydroxylapatite and promotes the growth of bone into the implant”, says Imgrund.

The engineers at IFAM have developed a granulate from the biomaterials which can be precision-processed using conven-tional injection moulding methods, obviating the need for any post-processing such as milling. The complex geometry is achieved in a net-shape process, producing a robust screw. The properties of this prototype come very close to those of real bone. Its compressive strength is more than 130 N/mm2, whereas real bone can withstand between 130 and 180. What’s more, the injection moulding process has a positive side effect. Normally, the powder injection moulded part has to be sintered at very high temperatures of up to 1400°C. “We only need 140°C for our composite materials”, says Imgrund. In future the engineers intend to develop other bioimplants using their energy-saving process.

Biodegradable PIM screws made by IFAM



Industry News

Out now: The new 14th Edition International PM Directory 2010-2011

The latest edition of the International Powder Metal-lurgy Directory (IPMD) has just been published by Inovar Communications Ltd, Shrewsbury, UK. This highly regarded reference publication has been an essential source of information on the global PM industry since the first edition in 1977.

The latest 504 page 14th Edition contains over 4800 entries, making it the most comprehensive guide to powder metallurgy (PM) component producers and PM industry suppliers worldwide.

As well as structural PM components, the directory also covers Metal Injection Moulding, Hard Materials/Cemented Carbides, Diamond Tools, Sintered Magnets and much more. Users benefit from an accompanying on-line search facility that makes light work of sourcing part, material and equipment suppliers wordwide.

In addition to being a comprehensive directory of PM producers and suppliers, the IPMD contains 170 pages

of editorial content, including essential statistical data on the PM industry and reviews covering all major sectors of PM technology.

Further information on the 14th Edition International Powder Metallurgy Directory (ISBN: 978-0-9558223-1-5) is available at www.ipmd.net

2010 Powder Metallurgy thesis competitionThe European Powder Metallurgy Association (EPMA) is inviting submissions to its biennial Powder Metallurgy Thesis Competition for 2010, in both Diploma (Masters) and Doctorate (PhD) levels. The competition, sponsored by Höganäs AB of Sweden, aims to develop interest in and promote PM among young scientists at European academic establishments, and to encourage research at under-grad-uate and post-graduate levels. The organisers state that the subject of the thesis must be capable of being classified under the topic ‘Powder Metallurgy’, including MIM.

The winners will receive a cheque for €750 for the Diploma/Masters category and €1000 for the Doctorate/PhD category. Prizes will be awarded at the PM2010 World Congress & Exhibition, Florence, Italy on Tuesday, 12th October 2010. Both winners will have free registration to the PM2010 World Congress and Exhibition and their thesis published in the journal ‘Powder Metallurgy’. The deadline for submitting an entry is Friday, 14th May 2010.

www.epma.com/thesiscompetition



Industry News

Chinese carbonyl iron powder producer Yuelong looks to step up qualityYuelong Superfine Metal Co., Ltd (YSMC) based in Guangzhou, China, is the leading Asian producer of carbonyl iron powder, much of which sees use in metal injection moulded component production.

The company states that it is committed to offering quality and cost-effective carbonyl iron powders for its customers’ specific applications. In order to further develop its product quality specifically for MIM applica-tions, the company has stated that it is now working with Prof. Randall German, San Diego State University, USA, to provide expertise and assistance to improve the company’s powder processing technology and make it more compatible for MIM industry.

Mr. Li Shangkui, President of YSMC, stated, “This is a complementary arrangement. YSMC obtains access to state-of-the-art chemical engineering and powder processing facilities and management, while Prof. German can benefit from an insight into our operations and those of an increasingly sophisticated Chinese PM industry.”

www.ylcip.com

Seibersdorf awarded patent for PIM lattice used for medical stentsAIT Austrian Institute of Technologies GmbH, formerly Austrian Research Centres GmbH - ARC, has been awarded both World and European Patents for the use of powder injection moulding to produce metal lattice parts, including biodegradable magnesium alloys, used in the manufacture of medical stents using the lost core technology where the lost cores and/or stents are made by MIM or CIM. The lattice comprises a connection made of knots, and perpendicular to the lattice surface are lattice bars and lattice knots of the same thickness (less than 1mm). The size of the gaps in the lattice are less than 50 mm2. Patent Number: WO2008/101265

Carpenter launches new alloy for knife blade applicationsCarpenter Technology Corp, based in Wyomissing, PA, USA, has introduced a new alloy which is part of the Carpenter CTSTM alloys range used for consumer, industrial and medical knife applications. The new alloy designated Carpenter CTS-BD1 contains metal additions which the company states offers enhanced knife blade edge retention and surface finish as well as an ability to be machined to a fine edge. Ten of the Carpenter CTS alloys are offered in strip form and four are manufactured using PM techniques.

www.cartech.com



New ‘Powder Metallurgy Global Market Review’ from Inovar CommunicationsInovar Communications, publishers of Powder Injection Moulding International, has just published the latest edition of its report “Powder Metallurgy: A Global Market Review”. This 10,000+ word document, featuring 22 tables and 23 charts, reports on trends in all key sectors of the PM industry.

Key statistics in regional and global shipments relating to ferrous and non-ferrous PM products, hardmetals, diamond tools, PM semi-products and powder-based magnets are presented. Two additional inset features review PM’s special relationship with the automotive industry and the growing end user acceptance of MIM.

The review, compiled by Bernard Williams, former Executive Director of the European Powder Metallurgy Association, is published in the latest 2010-2011 Interna-tional Powder Metallurgy Directory (IPMD) or is available to download separately as a PDF document from www.ipmd.net for £125.00.

For further information visit www.ipmd.net/pdf

GKN reports sharp drop in sales but stays in the blackResults issued by GKN plc for fiscal year ending 2009 showed that despite a 25% fall in sales for the Automotive Products division (including powder metallurgy), the division was able to report a £7 million profit. The company reported overall Group sales down 3% to £4.468 million and profits for 2009 of £152 million.

Sir Kevin Smith, CEO, stated that GKN had made signifi-cant progress in realigning its operations to weaker markets and preserving cash. “In response to the global recession we restructured the Group to reduce break-even points in the Automotive, Powder Metallurgy, and Off-Highway by around 20% and re-positioned our Aerospace business for lower aircraft production volumes in 2009. As a result all divisions were profitable in the fourth quarter with the exception of Off-Highway”, said Sir Smith.

The original restructuring plan included reducing global headcount by around 5,260 people by July 2010 with 13 manufacturing sites to be closed.

China establishes MIM PortalAfter nearly a year of preparation and design, a domestic metal injection moulding (MIM) portal has been launched in China, www.chinamim.net.

The Chinese-language portal aims to promote MIM technology inside and outside of China with information on process technology, companies operating in the sector, examples of MIM components, product leads for powders and production equipment, and other relevant market information.

www.chinamim.net

Industry News



Industry News

Regarded by many as ‘Mr MIM’ in the German-speaking MIM community, Dr Frank Petzoldt was recently presented with the prestigious Skaupy Prize by the German Ausschuss fur Pulver-metallurgie during the 2009 Hagen Symposium. This was in recognition of his many contributions to powder metallurgy over the last 20 years, in particular to metal injection moulding.

Ingo Cremer, President of the Euro-pean Powder Metallurgy Association, said that Dr Petzoldt graduated from the University of Brunswick, Germany and received his doctorate for work on Mechanical Alloying from the Technical University Clausthal. In 1984 he joined the Fraunhofer Institut fur Angewandte Materialforschung (IFAM) in Bremen, northern Germany, as a researcher and was largely responsible for setting up the comprehensive powder metallurgy research section at IFAM, which was featured in the September 2009 issue of PIM International. Here he dedicated himself to developing new PM and MIM technologies and to solving industry problems in cooperation with industry partners. Dr Petzoldt has been Deputy Director at IFAM since 1999 and has additionally taken on teaching roles at universities in Bremen and Bremerhaven.

MIM has been at the heart of Dr Petzoldt’s work since the early 1990s. In 1993 he set up the MIM Expert Group within the German Fachverband Pulvermetallurgie where he is affec-tionately known as ‘Mr MIM Deutsch-land’. This group initiated collaborative

projects, promotional activities for MIM, and work on standardisation including achievable tolerances for MIM parts and mechanical property specifications for the most common MIM materials. Originally made up of five members the German MIM Expert Group now has 42 members, an indication not only of the growth of MIM production in Germany but also to the dedication and energy which Dr Petzoldt has given to making this relatively small community successful.

Scope and future for MIMIn accepting the Skaupy Prize at the Hagen Symposium in late November 2009, Dr Petzoldt gave a presentation on developments at IFAM and on the scope and outlook for MIM. He referred to the rapid growth of MIM production over the past two decades, and the

growing range of feedstock materials which are now available to manufac-turers in this sector. It was interesting to note, he said, that whilst the process originated in North America, Asia is today achieving the fastest growth with the manufacture of MIM parts in Asia now accounting for some 50% of global production and the remainder divided fairly equally between Europe and N. America. The majority of MIM producers in Europe are located in Germany, said Dr Petzoldt.

Dr Petzoldt stated that IFAM has worked with various industry partners to overcome processing problems for a range of MIM materials. Included is titanium, which currently makes up only around 1% of MIM production but which he believes will grow as producers are now able to achieve the expected tolerances and properties

‘Mr MIM’ receives the Skaupy Prize at the 2009 Hagen Symposium

Fig. 1 Dr Frank Petzoldt (right) receives the Skaupy Prize from Ingo Cremer, President of the EPMA (centre left). Also present are Prof. Herbert Danninger (TU Vienna) (left) and Hans Kolaska (Fachverband Pulvermetallurgie FPM) (centre right)

Properties PM Magnets MIM Isotropic MIM anisotropic

Sintered density [g/cm3] 7.5 7.48 7.55

Oxygen Content [%] 0.45* 0.5-0.10 <0.5

Carbon Content [%] 0.02* 0.3-0.4 0.3 - 0.4

Remanence Br [mT] 1050-1150 - 1200

Coercivity HcB [kAm] 850 - -

Max. Energy (BH) max [kJ/m3] 210-250 70 -

Alignment [%] ≥ 90 none ≥ 90

* Based on measurement of the starting powder, possible to modify by processing

Table 1 Comparison of magnetic properties of P/M and MIM sintered NdFeB magnets



Industry News

System solutions from one single source

www.erowa.com [email protected]

Are you saving time?

You can find out more about the EROWA quick change tooling system for dies and die-plates on www.erowa.com

We are: with the PM Tooling System for flexibleand quick resetting!

demanded for medical components, the main applications sector for MIM Ti. Another is the little publicised potential for MIM produced NdFeB magnets. Dr Petzoldt stated that MIM offered the possibilities of new designs of very small sintered anisotropic magnets and could therefore open up new applications. The MIM sintered magnet requires finely milled, single domain NdFeB powder particles less than 10 microns with oxygen levels in the range 0.2 to 0.45 wt% and carbon content of 0.02 wt%, he said. These powders lose their magnetic properties during sintering but can then be remagnetised through the influence of a strong external magnetic field. The NdFeB powders are mixed with a wax polymer binder comprising 15% ethylvinylacetate (EVA) and 85% paraffin and other waxes.

The injection moulding process developed by IFAM for these materials uses a specially designed mould which enables the application of a magnetic field during moulding and cooling by helping to orientate the particles parallel to their magnetic axis. A dedicated thermal debinding process has also been developed using partial vacuum, and a high vacuum 5.10-6 mbar is used for sintering the NdFeB magnets at 1095°C for 1 hr. Properties of MIM produced NdFeB magnets are shown in Table 1 and compared with pressed and sintered (PM) magnets.

Dr Petzoldt also referred in his Skaupy presentation to IFAM’s collaboration with Philips AMS in the Netherlands for the development of HID lamp electrodes produced by injection moulding of tungsten (see PIM International Vol.2, No.2, June 2008). Whilst such electrodes can be produced from extruded W wires, MIM technology offered a greater design freedom whilst achieving the required physical properties such as >95% sintered density, and close toler-ances (<0.6%). One such MIM tungsten electrode is shown in Fig. 2.

A further example of industry collaboration given by Dr Petzoldt is the production by MIM of gold semi-products which are further worked into finished jewellery pieces such as the gold wedding ring shown in Fig. 3. He stated that IFAM worked closely with the German precious metals company C. Hafner GmbH to perfect a MIM process for complex shaped 18ct gold pieces. This involved the develop-ment of a new debinding process to accurately control carbon content, and the need to monitor each stage of the sintering process in order to achieve a microstructure with a pore-free gold alloy surface having good workability. The resulting MIM ring semi-products were evaluated by jewellery experts for their workability.

Fig. 2 MIM tungsten lamp electrodes

At eMBe, we have the products and services to help you “shape up” your metal or ceramic powder.

Develop your products with us by using our lab and our experience in additives design for sintering materials.

eMBe is a leading additive supplier for the ceramic and powder metal industry in Europe. Our services focus on product development and product innovation to continuously meet our customers´ evolving needs.

Find our products applicable for

Ceramic Injection Moulding

Embemould® C and Licomont® EK 583

Compaction of metal powders

Embelube®

Metal Injection Moulding

standard and custom-made Embemould® Metal Feedstocks

Embemould and Embelube are registered trademarks of eMBe

Licomont EK 583 is a registered trademark of Clariant

To learn more, please contact us:

eMBe Products & Service GmbH Gemeindewald 7

86672 Thierhaupten, Germany tel.: +49 8271 421988-3 fax: +49 8271 421988-4

[email protected] www.embe-products.com

learn how to control the powder´s motion with eMBe



Industry News

Contacts:William R. Mossner

Dwight WebsterAdvanced Metalworking

Practices, LLC401 Industrial Drive

Carmel, IN 46032, USCarmel, IN 46032, USAe-mail: [email protected]

Phone: +1 317 843 1499Fax: +1 317 843 9359

www.advancedmetalworking.com

Feedstock for Metal Injection Molding

ISO 9001:2008 certifiedSupplier of quality feedstock ADVAMET Feedstock production from 25 lb to 1700 lb in one batchCan supply customers with lower cost, off-the-shelf, standard 4605 Alloy Steel and 17-4 PH Stainless Supplier of Customized feedstock made from numerous Supplier of Customized feedstock made from numerous ferrous and non-ferrous metals and alloys.

High Quality Feedstocks since 1988 - longer than any other supplier

At Advanced Metalworking Practices feedstock production is our only business. Our products are used widely for applications in industries such as medical andorthodontic, electronics, hardware and sporting goods.

®

Fig. 4 W-Cu heat sinks produced by bonding three MIM parts into one

IFAM also collaborated with W.C. Heraeus to develop a MIM process for a platinum/magnesium oxide composite powder where the particle size is less than 1 micron. This mixture had to be prepared in a glove box under argon. Feedstock preparation and injection moulding likewise had to be done under argon to avoid oxygen contamination of the Pt-MgO mixture. Solvent debinding was used and sintering resulted in a high density, shiny surface.

Two other examples of successful developments given by Dr Petzoldt were: (1) the design of a demonstrator NiTi memory alloy developed in conjunction with Centro Ricerche Fiat (CRF) for potential memory alloy appli-cations in the automotive sector; (2) as

part of an AIF Project W-Cu heat sinks (Fig. 4) have been developed which involved producing three separate MIM components and diffusion bonding these into one part during sintering. The W-Cu heat sinks are used in laser diodes.

Dr Petzoldt referred to the European Union funded MATLAW collaborative project in which IFAM is a project partner. This project aims to simulate two very important quality criteria in the MIM process - the homogeneity of MIM feedstock and also mould filling during injection moulding.

Another new research emphasis involves Neural Networks in the injection moulding process with the aim of providing an in-line quality checking system and allowing for the removal of defective parts immediately after injection moulding. Dr Petzoldt also reported that because sintering is such an important cost factor in the MIM operation, IFAM has installed

and linked a Quadrupole mass spectrometer to a sintering furnace in order to analyse the influence of sintering atmospheres (pure nitrogen, argon, and gas mixtures) during the evaporation of the binder from FeNi alloy MIM parts. Also being studied is the evolution of methane at the holding temperate of 600°C. Finally, Dr Petzoldt referred to ongoing work at IFAM related to 2-component powder injection moulding, and extrusion of MIM feedstock for comb-like profile structures.

We are sure that PIM Interna-tional readers will want to join us in congratulating Dr Petzoldt for his 2009 Skaupy Prize and to wishing him many more years of fruitful contributions to metal injection moulding.

Dr Frank Petzoldt has given 113 technical presentations so far, the majority of which involve MIM. He is one of the consulting editors of PIM International.

Fig. 3 18 ct Gold semi- and worked wedding rings made by MIM with microstructure



Acoustics used to detect flaws in MIM partsThe Modal Shop Inc. based in Cincinnati, Ohio, USA, has developed a NDT resonant acoustic method (NDT-RAMTM) which the company states detects internal and external flaws in metal injection moulded parts. The NDT-RAMTM systems are said to have proven effective for reducing liability and increasing confidence in zero defect shipments at major medical device manufacturers as an in-line quality inspection solution.

In contrast to the common X-ray, imaging, scanning and dimensional testing of MIM medical device components, NDT-RAM tests the whole part, internally and externally, to alert of anomalies and structural flaws in components and is covered by the ASTM E2001-08 Standard. Whole part testing is a valuable tool in screening for subsurface cracks or micro fractures. According to The Modal Shop the entire process can be achieved as fast as one part per second.

NDT-RAM works on the principle that every part has a unique vibration signature (resonant frequencies). These resonant frequencies will have little change from good part to good part. However they will shift when there is an internal or external change in the part from manufacturing variance or imperfection in the part. The company offers free feasibility testing of MIM parts allowing NDT-RAM to be evaluated in the factory before buying.

“In an industry with patient safety-critical parts, often needing a 100% inspection, the NDT-RAMTM system can significantly reduce the need for subjective visual inspec-tors, thus reducing the inevitable human error of missed flaws, as well as reducing cost for inspection,” said Gail Stultz, NDT product manager.

Email: [email protected] www.ndt-ram.com

APMI announces 2010 Fellows Award recipientsThe APMI’s has announced the 2010 recipients of its pres-tigious fellows award. The winners, Prof. Herbert Danninger and Myron I. (Mike) Jaffe, will receive their awards at PowderMet2010, Hollywood (Ft. Lauderdale), Florida.

Herbert Danninger is Full Professor for Chemical Technology of Inorganic Materials, at Vienna University of Technology, Vienna, Austria. He is internationally known for his analysis of issues based on sound technical and scientific principles, and, state APMI, has worked as an efficient bridge between Eastern and Western Europe.

Myron I. (Mike) Jaffe has devoted over 57 years to the PM industry and has been credited with making a significant contribution to educate potential end users about the advantages of powder metallurgy. Jaffe presently is a consultant with Brewer Hill Designs, LLC. His current consulting is supported by his strong academic achieve-ments and the experience that he gained in the PM industry while working for 36 years in various positions at Sintered Metals, Inc.

www.apmiinternational.org

Established in 1977Expert Designers and Builders of Powder Injection

Moulds Since 1988, Worldwide.

Contact: Jay Williams00-1-763-792-1244

©2009 Dynamic Group, USA

www.TheDynamicGroup.net

Our Award-Winning Customers Rely On Dynamic Moulds.

Industry News



Make plans to attend the only international metal and powderinjection molding event of the year!

• Focus on demanding applications• Leading process trends• Numerous case studies• Tabletop Exhibition & Networking Reception with representatives

from many of the leading companies in the field...and much more!

Register by February 28 and Save!

Taught by Randall M. German, world-renowned PIM expert

An ideal way to acquire a solid grounding in powder injection molding technology in a short period of time

• Introduction to the manufacturing process• Definition of what is a viable PIM or MIM component• Materials selection and expectations• Review of the economic advantages of the process

Visit mimaweb.org or mpif.org for complete program details and registration information

MIM2010 CONFERENCE(March 30–31)A two-day event featuring presentations and a keynote luncheon

Optional One-Day Powder Injection Molding Tutorial Precedes Conference (March 29)

This conference is sponsored by the Metal Injection Molding Association,a trade association of the Metal Powder Industries Federation

layout / 3 9/1/09 3:07 PM Page 1












layout / 3 9/1/09 3:07 PM Page 1



Two-component Powder Injection Moulding

Multifunctional parts by two-component Powder Injection Moulding (2C-PIM)

The ability to manufacture components in one step using two different materials is opening up a world of opportunities for the powder injection moulding industry. The possibilities range from combining metals with different properties through to metal/ceramic and ceramic/ceramic components. Dr. Frank Petzoldt looks at the development of this technology to-date and outlines the challenges that need to considered when planning a two-component PIM part.

Plastic components with a multi-material design are widely used in our daily lives and two-component plastic injection moulding technology is a well known and economical series produc-tion process. In the plastics industry, it enables the use of the same material in different colours in a product, or two different materials in the same or in different colours within one product. Examples of common multi-part / multi-colour products for everyday use or technical applications include:

tooth brushestoys food packaging electrical equipment engineering components.

With two-component injection moulding, moulded components composed of several parts or colours are produced on a single machine. It is, therefore, an economical production process avoiding further handling and assembly. Two-component injection moulding is the process of feeding two different melts, one after the other, into the same mould. The melts should make contact with each other but should not flow into each other.

Usually, a pre-moulded part is produced from the first material in an initial process step, which is then combined with the other material. As interest in ceramic and metal multi-

•••••

functional components has grown, so new economic manufacturing proc-esses have needed to be developed.

Once powder injection moulding was established as a mature tech-nology the natural next step was to look for further opportunities to broaden the scope of the technology. Two major trends emerged: miniaturisation and multi-functionality.

The advantage of powder injection mouldingThe two-component powder injection moulding process (2C-PIM) has been evaluated in recent years as a potential

manufacturing route for the fabrication of bi-material (metal/metal, ceramic/ceramic and metal/ceramic) parts.

The major advantage of 2C-PIM is the direct combination of two materials with different properties in a single production step, therefore eliminating the need for a subsequent joining process. The range of components that can be manufactured extends from hollow components with complex internal structures right through to flexible, non-detachable joints.

The following combinations of properties demonstrate some potential applications of 2C-PIM technology:

magnetic + non-magnetic•

Fig. 1 An ALLROUNDER 370 S 700-70 2 colour injection moulding machine from Arburg












layout / 3 9/1/09 3:07 PM Page 1












layout / 3 9/1/09 3:07 PM Page 1




electrically conductive + non-conductivehard + toughdense + porousexpensive + cheapcompact + hollow.

The objective in all cases is to manufacture components with enhanced functionality at favourable cost. Components that are subject to wear can be strengthened by using, for example, a harder or more resistant material at only critical areas and thus having a tailor-made component for an individual application. In particular, the combination of magnetic and non-magnetic materials allows completely new designs without an air gap.

Two-component injection mouldingFor two-component injection moulding processes twin-barrel injection-moulding machines are used. These standard two-component machines can be used for the following three processes.

1) Repositioning of the moulded part in the mould Multicomponent moulding using a servo-electric or servo-hydraulic rotary table is the most popular processing method for the production of multi-component or multicolor parts.

Process steps:

Injection of the first component Opening of mould

•

••••

1.2.

Fig. 2 Apparent Co-Sintering Index (ACSI) for five different magnetic/non-magnetic material combinations. Combinations 3, 4 and 5 with an ACSI of <15 would be feasible

Rotary table moves the preform on the moving mould half into the second position Closing of mould Parallel to the injection of the second component, the next preform is being moulded.

2) Rotation of the mould via an indexing unitWith indexing plate technology, the rotating mechanism is integrated in the mould. This method is applied where the moulding pattern of the preform differs from that of the second component both on the fixed mould half and on the moving mould half.

Process steps:

Injection of first component Opening of the mould Moulded components are transferred using a so-called indexing plate which is moved outward while the mould opens, then rotated by a special drive in the mould Closing of the mould Parallel injection of the first and second component to finish the first part and mould the new preform.

3) Composite injection mouldingBy rearranging the mould cavities, being in the first instance closed and then in the later stage opened, a composite part can be produced.This method enables injection of two different materials either simultane-

3.

4.5.

1.2.3.

4.5.

ously or in subsequent stages in the same mould.

Process steps:

Injection of the first componentPulling a coreInjection of the second component.

Alternatively the two materials can also be injected simultaneously in the same cavity. A special and quite complex mould design is in all cases necessary to succeed with the composite injection moulding approach.

The 2C-PIM processFor 2C-PIM all the above methods are in principal applicable. The relevant equipment versions are available as they are basically the same for 2C- plastic injection moulding. The two feedstocks can be injected through two different gates thus making up two well defined areas of the composed green part. Their exact distribution in the part is dependent on the injection process itself. For instance, the process can be controlled in a way that feedstock from one of the runners forms the skin of the component whilst feedstock from the second runner forms the core. The result is a complex-shaped part with two different materials in the core and at the skin, for example a wear resistant material at the skin and a tough material in the core.

The two-material green part then has to be carefully debound and sintered to form an intricate bi-mate-rial part.

A non-negligible variable in 2C-PIM is the binder system for the feedstock. For the materials that are to be combined, either the same binder system or, if that is not possible, at least two binder systems with a similar thermal behaviour should be used. If the binder components differ too much in their thermal expansion or thermal decomposition behaviour, part defects may occur as soon as during the cooling phase in the mould or during debinding.

The interconnection between the two components should be material-locking, if possible. The mechanical stability of the composite part can be assisted with an additional form-locking connection, e.g. by giving an outer material component a higher

1.2.3.




amount of shrinkage than the inner component, thereby adding compression strength to the material interface.

A further important factor for the formation of a stable material interface is the thermal expansion coefficient of the materials. During the cooling of the composite part after sintering, the difference in the expansion coefficients leads to stresses in the material interface that may later cause part failure.

For parts that are subjected to cyclical thermal loads, the adaptation of thermal expansion properties plays an important role. Therefore, the thermal expansion coef-ficient must be considered at the very beginning of the development of a material combination.

Prediction of feasible material combinations To produce defect-free and fully functionalised compo-nents by 2C-PIM it is simply not enough to understand the injection moulding behaviour of the two feedstocks. There are a number of important materials and processing requirements to be considered. Above all, it has to be appreciated that the two materials must sinter in the same furnace under the same sintering atmosphere.

The challenging task to successfully process functional composite structures by 2C-PIM is twofold. Firstly, during the sintering process, the two parts shrink with different rates which results in the development of biaxial mismatch stress at the contact zone that may lead to the interface delamination, cracking and pore-band formation. The difference in the coefficient of thermal expansion (CTE) may also cause interface cracking during the cooling step of the co-sintering cycle.

Secondly, during high temperature sintering diffusion of alloying elements along the boundary takes place and unwanted phases are formed which can deteriorate mate-rial properties. Experiments performed on the fabrication of composite layers from stainless steels, superalloys, tool steels, iron and low carbon steels, hardmetals and ceramics have revealed that sintering is the key process step in 2C-PIM. Furthermore it has to be considered whether both materials are solid state sintering systems or if a liquid phase is involved.

The combination of chemically incompatible materials may require additional development work. Taking a simple example, carbon could diffuse from one material into the other at the joint interface and so alter the mechanical and magnetic properties. Such a problem can often be overcome by careful selection of the material partners, but this will certainly put limitations on the range of applica-tions of 2C-PIM.

To determine the compatibility of two materials for successful co-sintering, the similarity of their sintering behaviour can be quantified through the definition of a parameter termed the “Apparent Co-Sintering Index (ACSI), based on the dimensional change of the materials versus time and temperature.

Results from experiments with various injection moulding feedstocks, including iron, low-alloy steels, high-alloy steels and hardmetals, indicate that when the ACSI is less than 15, the 2C-PIM process is feasible; and it becomes easier as the ACSI value decreases (Fig. 2).

Inovar Communications Ltd Tel: +44 (0)174� �41�89

Dogpole House, Dogpole, Fax: +44 (0)174� �69660

Shrewsbury, SY1 1EN, United Kingdom Email: [email protected] www.pim-international.com

Powder Injection Moulding International is the

only magazine dedicated to serving the global

PIM industry, comprising the metal (MIM),

ceramic (CIM) and carbide injection moulding

sectors. Don’t miss the latest commercial and

technological developments from this dynamic

high-growth industry.......

PIM International: the only publication dedicated to covering the global PIM industry

For in-depth coverage of the PIM industry....

Exclusive PIM industry news

Specially commissioned features

Company visits

Technical papers

plus conference reports, patents and much more

Subscriptions are £95 for 4 issues. For more

information visit www.pim-international.com/subscribe

•

•

•

•

•

Full page PIM March 2009.indd 1 16/02/2009 15:55:31

In-depth coverage of the PIM industry....

Benefit from more than 250 pages of news, features and technical papers on the global MIM and CIM industries for only £95.

Subscribe today at www.pim-international.com




SimulationSIGMASOFT is a 3D-injection moulding simulation product from SIGMA Engineering GmbH, Aachen, Germany. SIMGA Engineering is a leader in casting simulation software and during the past three years has invested significant development to extend the SIGMASOFT product line with the addition of a specific PIM-module.

Since the end of 2008 a validated simulation product has been avail-able to simulate and optimise the injection moulding process for PIM feedstocks. Even the prediction of phase separation is possible by running two subsequent simulations. A first simulation highlights the cavity and runner locations where the separation of powder and binder is initiated by evaluating the shear rate results. In a second simulation, virtual tracer particles are released in the identified

shear field maxima and the flow history is visualised to identify probable defect locations of the green component. To know this in advance before building the mould helps to reduce development times and costs significantly and leads to stable processes and improved product quality.

Furthermore, SIGMASOFT has extended its existing Multicomponent Plastic Injection Module by developing a 2C-PIM simultaneous simulation as part of an R&D project co-sponsored by the German government (Fig. 3). This figure shows a two component MIM tensile bar filled with a magnetic and a non-magnetic feedstock. Fig. 4 shows a sliced view through the contact zone of the two materials and the corresponding microscope cut-view of a real moulding. The comparison of simulation and experiment shows promising results.

Advancing the processIn 2C-PIM, the sintering step involves high temperatures, holding times, diffusivity and consequently, interdif-fusion of alloying elements and phase formation, which are essential aspects for the interface of materials with unequal chemical compositions

Further information about the inter-diffusion of the alloying elements at different sintering conditions is still an unsolved area of research and complex thermodynamic calculations should be applied. There has been much recent development using thermodynamic simulation software packages in the last few years and the application of simulation could be extended to fine analysis of the sintering step for 2C-PIM. Thermodynamic simulation software could, therefore, be a valuable tool to predict interdiffusion element profiles and phases close to the inter-face using different process conditions, in order to save time and costs with the demanding tests and analysis

The DICTRA and Thermo-Calc software packages present interesting perspectives and qualities to predict the interface of different materials. Thermo-Calc works with thermo-dynamic equilibrium and suitable databases for several materials. DICTRA is pioneering software for accurate simulations of diffusion in multi-component alloy systems. DICTRA is coupled with Thermo-Calc for necessary thermodynamic calculations and has been applied to numerous problems of practical and scientific interest. Phase diagrams of complex alloys and diffusion paths of alloying elements can be created with this software.

Case StudiesMagnetic/Non-MagneticA focus was initially put on combining magnetic and non-magnetic materials. This was achieved by combining high-alloy steel grades 316L and 17-4PH. The austenitic 316L is soft and non-magnetic, whilst the 17-4PH can be magnetised due to its martensitic structure. The two steel grades are available as comparable powders that could be processed under similar sintering conditions.

There is greater scope for adjusting the magnetic properties of iron. For this reason, a composite material made of 316L and iron was also

Fig. 3 SIGMASOFT simulation of simultaneously injected magnetic/non-magnetic materials into a 2C-MIM tensile bar

Fig. 4 Comparison of SIGMASOFT simulation and microscopic analysis of the contact zone (sliced view)




manufactured. For this combination of materials, the difference in the sintering behaviour was considerably greater and this is reflected in the ACSI value (Fig. 2, combinations 1 and 2).

By employing a suitable mixture of powders comprising pure iron and a Master Alloy, which includes the alloy components for 316L (Fig. 2, combina-tion 5), the sinter properties were adapted to the pure iron, thus allowing the successful manufacturing of parts.

To highlight the feasibility of 2C-µMIM, two demonstrators were designed and manufactured. The first part was a magnetic positioning encoder consisting of a non-magnetic bar (316L) with two ferromagnetic cubes at the end (17-4PH). These cubes were moulded first and used as inserts before injecting the 316L material as the second component. The sintered demonstrator is shown in Fig. 6. The interface area was about 850 x 850 µm². When moving the parts in front of a hall sensor, a change in the magnetic field was detected that could be transferred to a change in position relative to the sensor.

The second demonstration part, a miniature tachometer, was also moulded on a twin-barrel injection moulding machine. One of the five wings of this part was separated from the rest of the cavity by a gate during injection of the non-magnetic 316L feedstock. After the first moulding step, the gate was opened and the ferromagnetic wing was moulded from the 17-4PH material. Hence, handling

of inserts to achieve the two-material part was avoided in this process.

Fig. 4 shows the interface of the sintered part obtained with this manu-facturing route. The interface area was 1 x 1 mm² in the sintered state. It can be seen that a solid bond of the mate-rial interface was obtained, though

some displacement of the interface compared to the gate position in the tool was observed. This was related to the high moulding pressures and tool temperatures applied. Moulding was achieved without cracking and the position of the interface could be adjusted by reducing the injection moulding pressure for the 17-4PH component.

The feasibility of µMIM of bimetal parts has been shown for magnetic/non-magnetic combinations 316L/Fe and 316L/17-4PH. The findings can be summarised as follows:

Proper co-sintering compatibility was obtained for 316L / 17-4PH combination. The magnetic properties of the co-injection moulded parts are adjustable by controlling the co-sintering route. Besides the

•

•

Fig. 5 Magnetic micro positioning encoder

porosity content, the amount of magnetic phase in the 17-4PH stainless steel depends on the sintering temperature. Therefore, the sintering condition strongly influences the magnetic proper-ties and thus must be controlled.The compatibility between Fe

and 316L stainless steel for the co-injection moulding process is not adequate, i.e., the maximum mismatch strain is 11.8 %. However, the compatibility can be improved by using a master alloy for preparation of the stainless steel counterpart. In this case, the maximum mismatch strain reduces to 2.8 % which is good enough for fabrication of very small parts with contact areas less than 1mm2.Reduction of interface dimensions leads to higher tolerance towards shrinkage mismatch. This can enhance the possibilities of this process especially for micro applications.

Even though the composite material made of 316L and H13 is also magnetic – non-magnetic, its applica-

•

•

Fig. 6 Magnetic micro tachometer made of 316L and 17-4 PH stainless steels

‘the interdiffusion of the alloying elements at different sintering

conditions is still an unsolved area of research’




tions tend towards the combination of a hard strong steel (H13) and a soft, tough steel.

Ceramic/CeramicIn the mid-1990’s the first basic investigations in the 2C-PIM of ceramic/ceramic were carried out with the following material combinations:

A demonstrator consisting of a core from Al2O3 with a particle

size of 1 µm and a shell of Al2O3 with an average particle size of 0.5 µm.A reinforced component consisting of a core from Al2O3 and a shell containing 20% partially stabilized ZrO2

A ceramic heating needle from different mixtures of Al2O3 and TiN.

More recently, two developments within the EU-funded project CarCIM have proved the feasibility of both high-pressure and low-pressure 2C-PIM of two ceramic materials with different material properties. In this project, a gear for fuel pumps and a

•

•

•

heater plug for diesel motors were successfully produced.

The heater plug, developed in co-operation with the Slovenian company Hidria AET, combining an electrically isolating and a conductive material (both made from a mixture of silicon nitride ceramic powder and a varying amount of grade C MoSi2 powder) was manufactured by low-pressure injec-tion moulding (Fig. 7). The conductive component was injection moulded

first and transferred into a second cavity, where the isolating material was added. Mass temperatures during moulding varied between 65 and 115°C and injection pressures from 0.5 to 0.6 MPa. Debinding was carried out under a nitrogen atmosphere at 700°C, and the heater plugs were sintered at 1750°C, also in a nitrogen atmosphere. Thanks to the matching thermal expansion coefficient and the adjustment of the shrinkage behaviour of the two feedstocks, the co-sintering of the two materials caused no difficulties whatsoever.

During testing, the heater plugs were submitted to defined voltages

and their time/temperature curves and the power input were character-ised. At a defined voltage of 13 V, a temperature of 1250°C at the spike of the plug was reached in three seconds.

Not only does the newly developed heater plug have a longer lifespan due to its better corrosion-resistance, but it is also cheaper to produce than conventional metallic heater plugs and, moreover, better suited for the new generation of more efficient diesel motors with their higher opera-tion temperatures.

Metal / CeramicMetal-ceramic components have some applications for medical instruments. Fraunhofer IKTS, Dresden, Germany, developed a bipolar grasper in close cooperation with the manufacturer of surgical instruments Olympus, Winter & IBE in Hamburg, Germany. The bipolar grasper is a minimal invasion surgery instrument, only about 5 mm wide and conducts a high-frequency current that heats the instrument at the tip. This way, the grasper can directly grip, cut and coagulate the infected areas of tissue. In contrast to conventional bipolar instruments, that only have one electric pole and discharge their electric current through the human body, the new grasper has one pole in each jaw, made from stainless steel

‘2C-PIM has the potential to expand the market of PIM components

substantially’

Fig. 7 Heater plug green parts and testing of the sintered parts (inset) (Courtesy Fraunhofer IKTS)

Fig. 8 An example of a two-component CIM component. This CIM gear wheel combines alumina and zirconia toughened alumina (Courtesy Fraunhofer IKTS, designed by Robert Bosch GmbH)




Fig. 9 CAD drawing of the bipolar surgical grasper, stainless steel (blue) and ceramic protective coating (grey) (© Olympus, Winter & Ibe)

and shielded by the non-conducting ceramic outer coating.

To achieve a stable and strong metal/ceramic interface, the grasper is produced by coating the mould with a thin ZrO2 tape layer and then injecting a stainless steel feedstock that is modified by adding reactive elements like titanium or silicon that later, during sintering, diffuse towards and into the ceramic layer, creating the stable interface.

The first tests of the new grasper show very promising results, however, long-term testing must now be performed to find out if the ceramic coating can withstand the aggressive cleaning and disinfecting processes in medical autoclaves.

ConclusionToday two component powder injec-tion moulding (2C-PIM) is a niche technology. Nevertheless it is growing and advancing from R&D status to industrial realisation for macro- and micro-parts.

Its ability to produce magnetic/non-magnetic components, different ceramic/ceramic products or stainless steel/zirconia parts has been demon-strated and is going to be transferred to industry. Certainly there are limita-tions: not all material combinations seem to be feasible because of the necessity of a common sintering step. Due to its unique potential to tailor different material properties within one component without any assembling operation, 2C-PIM has the potential to expand the market of PIM components substantially.

Intelligent use of the technology offers cost-effective and industrially adaptive solutions to many technical problems. It can potentially replace manual assembly for a wide range of functional products. The quality of 2C-PIM parts has to be optimised by tuning the processing factors.

AcknowledgementsThe author would like to thank Dr. Reinhard Lenk and Dr. Tassilo Moritz from Fraunhofer IKTS in Dresden, who have provided valuable help and much interesting information concerning 2-component ceramic injection moulding, the EU-funded project CarCIM and the BMBF-funded project GreenTaPIM.

Thanks also to Dr. Volker Piotter

from KIT Karlsruhe Institute of Tech-nology for the excellent co-operation in the BMBF-funded project 2K-PIM.

Literature[1] Tan L., Baumgartner R., German R., Advances in Powder Metallurgy and Particulate Materials 2001, Metal Powder Industries Federation, Princeton, NJ, 4.191-4.19

[2] Imgrund P., Sinterverhalten und Grenzflächeneigenschaften von Werkstoffverbunden aus 316L/17-4PH und 316L/Eisen, hergestellt durch Mikro-Metallpulverspritzgießen. phD Thesis, University of Bremen, Germany 2008

[3] Imgrund P., Rota A., Proc. of the Micro System Technologies Munich (2003), 218–225

[4] Thermo-Calc Software AB, DICTRA Example Collection – Version 24.

[5] Simchi A., Petzoldt F., Hartwig T., An Approach for Assessment of Sintering Behaviour of Co-injection Moulded PIM Feedstocks by Dilatometric Analysis, Proc. PM World Congress & Exhibition (PM2005), Prague (2005), pp. 357–363.

[6] Thornagel M., Simulation of 2-Component CIM Process Chain - Injection Moulding Simulation -, CARCIM Workshop, Besancon, 2008

[7] Thornagel M., MIM-simulation: A virtual study on phase separation, EuroPM 2009, Copenhagen

[8] Baumann A., Moritz T., Lenk R. Manufacturing of ceramic-metal

composites using multi-component injection moulding, EuroPM 2007, Toulouse

[9] Baumann A., Moritz T., Lenk R., Manufacturing of ceramic-metal composites by combinig tape casting and injection moulding, ECerS, Berlin, 2007

ContactDr. - Ing. Frank Petzoldt Director, Powder Technology Department Fraunhofer IFAMWiener Straße 1228359 BremenGermanyTel: +49 421 2246-211Fax: +49 421 2246-300Email: [email protected]



Titanium powder injection moulding: Ti-PIM

Because you can never have too much industry knowledge

The New 14th Edition 2010-2011 International Powder Metallurgy Directory

290 pages of new customers or suppliers

Listings of more than 4800 organisations involved in PM, from part producers to materials & equipment suppliers

Products & services described using 200 product codes

Covers PM, MIM, Hardmetals, Sintered Magnets & much more...

•

•

•

170 pages of market and technology information

170 pages of market and technology data

Includes the 2010-2011 edition “Powder Metallurgy: A Global Market Review

Written by invited experts from around the world

•

•

•

Plus FREE on-line directory accessAll purchasers can search our complete industry database on-line for 12 months

Easily search for specific products by country or world region

Your essential reference guide to PM

•

•

•

All for only £190 inc. shipping www.ipmd.net

IPMD MARCH 2010.indd 1 3/5/2010 9:19:50 AMMarch 2010 Front Section.indd 28 3/5/2010 1:40:41 PM


Company visit: Parmaco Metal Injection Molding AG

Parmaco Metal Injection Molding AG: High tech MIM manufacturing in a Swiss rural retreatFischingen, the most southerly community in eastern Switzerland’s Canton Thurgau, nestles in rolling green and wooded hills. The small community is renowned for its former Cisterian monastery and the region, which borders Canton Zürich, is a hikers’ paradise only 40 minutes from Zurich Airport. Less well known is that Fischingen is the home to Parmaco Metal Injection Molding AG, one of Europe’s leading and most innovative MIM producers since 1992. Bernard Williams reports on his recent visit for PIM International.

Georg Breitenmoser, Parmaco’s Managing Director, is a native of this part of Canton Thurgau and studied at the Swiss Federal Institute of Tech-nology, Zürich, where he graduated with a degree in Materials Engineering in 1981. He had chosen metallurgy in his final year because he felt it gave him more options for travel and career opportunities in a country which he stated is dominated by chemical and pharmaceutical giants. His first job after graduating was with Oerlikon, near Zürich, a company specialising in producing welding machines and welding consumables such as pressed stick electrodes coated with flux and alloy steel powders.

Initially he worked in the R&D department but was later made responsible for providing technical support to Oerlikon’s many licensees around the world, thus helping him to fulfil his wish to travel. In 1984 he was given the opportunity to work for a licensee in Lima, Peru, where he developed alloy steel (13Cr steel) welding electrodes used to refurbish turbine parts used in hydroelectric power plants.

A new chapter in Georg Breiten-moser’s life started in 1987 when he decided to embark on a MBA at California State University in San Luis Obispo and it was during his stay in California that he made a visit in 1988

to Carl Zueger, a fellow Swiss and co-founder of one of the world’s first metal injection moulding companies, Parmatech Corp. based in Petaluma near San Francisco. The visit made sufficient impression on Breitenmoser to convince him of the future potential for MIM technology and he was offered a manufacturing license to use Parmatech’s patented technology in Switzerland.

It took four more years, however, before Breitenmoser’s ambitions to set up a MIM plant in Switzerland could be realised. He first undertook, together

with his father and two other partners, to set up a small manufacturing plant to produce central heating radiators from sheet steel in the nearby town of Münchwilen in 1989. Then in 1992 he founded Parmaco. He rented part of a modern building in Fischingen which suited his initial needs for a small MIM operation - one of the first in Europe. The company purchased a 50 ton Arburg Allrounder injection moulding machine, a planetary mixer and a solvent debinding unit. Breitenmoser built his own furnaces for thermal debinding and sintering based on

Fig. 1 Georg Breitenmoser, managing director of Parmaco AG in Fischingen, Switzerland

Because you can never have too much industry knowledge

The New 14th Edition 2010-2011 International Powder Metallurgy Directory

290 pages of new customers or suppliers

Listings of more than 4800 organisations involved in PM, from part producers to materials & equipment suppliers

Products & services described using 200 product codes

Covers PM, MIM, Hardmetals, Sintered Magnets & much more...

•

•

•

170 pages of market and technology information

170 pages of market and technology data

Includes the 2010-2011 edition “Powder Metallurgy: A Global Market Review

Written by invited experts from around the world

•

•

•

Plus FREE on-line directory accessAll purchasers can search our complete industry database on-line for 12 months

Easily search for specific products by country or world region

Your essential reference guide to PM

•

•

•

All for only £190 inc. shipping www.ipmd.net

IPMD MARCH 2010.indd 1 3/5/2010 9:19:50 AM March 2010 Front Section.indd 29 3/5/2010 1:40:49 PM



Parmatech specifications. The first person employed was

a toolmaker and the young team at Parmaco focused first on getting MIM part design and process stability under control. “We found the MIM process relatively unstable so we designed our own production cells in order to achieve the desired control of temperature in debinding and sintering

and as a consequence control of dimensional accuracy in the MIM parts. It’s one thing being able to achieve dimensional accuracy in a lab furnace, but it’s another to achieve the same in a production environment”, Breiten-moser said.

An additional challenge was that very few design engineers knew about MIM in the early 1990s. “We had no MIM parts in production when we first exhibited at the Hannover Trade Fair in April 1993”, said Breitenmoser. The company’s stand which promoted examples of MIM applications in arma-ments, office machines, computers, etc., did, however, manage to generate quite a few enquiries one of which turned into an order for its first MIM

part. “This was a ‘breech lock holder’ (Verschlusshalter) used in a Swiss made air pistol produced by Hammerli, then located in Lenzburg, Switzerland, and we were able to make this as a single MIM part from an FeNi alloy against an assembly of machined parts previously used”, said Breitenmoser.

The second MIM part was developed together with Festool, a leading

producer of professional power tools, in 1993. This part was also made from FeNi alloy and was used in a jig saw blade holder assembly in the then PS200 model jig saw. Parmaco was able to beat investment casting on price, tolerances and finish.

Today, Parmaco has some 250 active MIM parts in production ranging in weight from 0.05g to as heavy as 90g, although the preferred upper weight range is put at 50 to 60g and Breiten-moser puts the ‘ideal’ MIM part size at under 20g. “Because of the complexity of MIM parts and the associated high tooling costs for injection moulding, our production quantities tend to start at a minimum of 10,000 parts/year with an upper range of 3 million parts/year

depending on MIM part size and weight,” said Breitenmoser. Around 60% of Parmaco’s MIM production is based on low alloy steels (NiFe), and the rest is dominated mainly by various stainless steel grades but also some controlled expansion alloys, soft magnetic parts, tungsten heavy alloys and a limited number of tungsten carbide wear resistant MIM parts.

Over the past 18 years the company has gradually taken over the whole of the building it rents in Fischingen. However, it remains a relatively small to medium size operation employing some 50 people, and Breitenmoser emphasised that the company was not geared to very high volume MIM production.

“We prefer to focus on small or extremely small and complex MIM parts where material cost is a comparatively minor factor, and where the MIM process can achieve up to 100% material utilisation through the elimination of any secondary machining steps. In this way we can success-fully compete with parts produced by competitive technologies which require extensive secondary machining”, said Breitenmoser. “Our strategy is to sell high quality service and design solutions to our customers, and not to compete for high volume parts with depressed prices. Our batch furnaces are in any case more suited to medium volume production”.

This strategy and Breitenmoser’s passion for MIM technology has, he

Fig. 3 Injection moulding of MIM parts at Parmaco.The six axis robot gripper is picking two parts

Fig. 2 Good tool maintenance is critical to the success of metal injec-tion moulding

‘We prefer to focus on small or extremely small and complex MIM

parts where material cost is a comparatively minor factor’




stated, paid handsome dividends with applications over a wide range of end user sectors including fire arms, medical, power tools, textile machines, telecoms, optical and automotive. Approximately 80% of production is exported with a large proportion going to German customers – an indication perhaps of the success of exhibiting every year at the Hanover Trade Fair.

In recent years annual growth has averaged 10 to 15% requiring 3-shift working in the MIM plant. In 2008 Parmaco saw sales surge by 30% as new MIM parts were put into produc-tion. “This high level was maintained until March 2009 when there was a sharp downturn in demand and 2-shift working was introduced”, said Breitenmoser. Order volumes started to pick up again in the second half of 2009, and the company was expecting to consume around 50 tonnes/year of MIM feedstock in the last year.

Expertise in MIM feedstockParmaco produces all of its own MIM feedstock, which was originally based on the formulae licensed from Parmatech in the USA, but which has in many cases been changed or modi-fied to suit production of a particular component or material. Mixing is done in 50 kg lots in planetary mixers using a soluble wax binder and a non-soluble thermoplastic backbone binder with elemental metal powders such as carbonyl iron, nickel and other metals as required, as well as water and gas atomised stainless steel powders. Process controls are in place to ensure a consistent dispersion of metal powder particles and binder throughout the feedstock. Parmaco uses a weighing station where each ingredient material is accurately weighed, based on the specified formula kept on a database. The mixed binder/metal powder feedstock, which typically has a 55 to 60% powder loading, is then processed into pelletised feedstock and stored in 20 kg drums ready for injection moulding.

Moulding / debindingMIM tooling is now mostly produced by outside contractors with only tool maintenance done in-house. Tooling tolerances are critical to the success of the injection moulded parts and Parmaco can achieve an accuracy of better than +/- 0.3% in its MIM

Fig. 6 A line of batch sintering furnaces

Fig. 4 A dimension on a housing part cover is being measured in Parmaco’s quality control department

Fig. 5 MIM parts being loaded into the combination debinding and sintering furnace at Parmaco




process, which means that even for extremely small and complex parts moulding accuracy can be in the range of hundredths of a millimetre. Surface finish of better than Ra 3.2 is attainable without the need for polishing. In the case of micro-MIM parts, Parmaco’s toolmakers are expected to produce tools capable of close to zero toler-ances. Some moulds contain up to eight die cavities. “It is very important to create a good design of MIM parts and the associated moulding tools in order to avoid problems in produc-tion”, said Breitenmoser. “Our part designers and toolmakers work closely with customers as early as possible in the design process to avoid such problems”, said Breitenmoser.

Parmaco operates a total of eight injection moulding machines including a Netsal 60 ton hydraulic press, a line of 50 ton Arburg machines of which some are fully electric and a Battenfeld 5 ton machine which is used for injection moulding extremely small and so-called micro-MIM parts. Moulding pressures are in the range of 800 to 1600 bar.

Many of the injection moulding cells are fully automated using robotic devices to remove runners from the moulded parts and to place the parts onto trays for debinding. On one machine seen producing a gun hammer part, the robot placed the parts onto a tray and when the tray is full the robot’s gripper is automatically changed to allow it to place the tray onto a stack. The whole stack can then be taken to the solvent debinding unit.

As already mentioned, Parmaco’s binder systems are based on a soluble wax and an insoluble backbone thermoplastic. The first step in the debinding process involves solvent extraction whereby the moulded parts are immersed in a hexane bath. This dissolves the wax binder element and leaves the parts with around 20% porosity having interpenetrating pore channels which are needed for the second stage of the debinding process. The ‘solvent extraction’ stage is relatively short and there is no change in size of the parts at this stage, stated Breitenmoser.

The next ‘thermal debinding’ stage

is more critical in terms of temperature control during the evaporation of the backbone thermoplastic binder from the parts. Parmaco uses four batch thermal debinding furnaces which the company has designed in-house with each furnace having a loading capacity of 1m3 and operating at temperatures up to 300°C. To ensure uniform debinding the company is able to main-tain temperature accuracy to +/-1°C in its furnaces where the gradual heating of the parts attacks and evaporates the binder constituent without loss of shape. The ‘brown’ parts which emerge from the thermal debinding furnace have still more or less the initial size but have gained more porosity.

Custom-built sintering furnacesEqually impressive to the furnace units seen for thermal debinding are the sintering furnaces which Parmaco has also designed in-house. There are four top loading batch furnaces with inte-grated fan cooling used for sintering low alloy steels in hydrogen atmos-

Fig. 9 MIM part having extremely intricate shape and thin walls for a mounting unit used to position a glass prism in an optical lens system

Fig. 10 MIM part used in a nut tightener system for special self drilling flat head screws for facade construction

Fig. 8 Award winning Micro-MIM high torque planet-carrier produced by Parmaco

Fig. 7 Selection of small and micro-MIM parts in production at Parmaco



phere at temperatures up to 1300°C. Gas flow is said to be critical in these furnaces and temperature sensors placed strategically help to control the temperature throughout the working zone of the furnace. A horizontal loading atmosphere batch furnace is also available for sintering up to 1300°C, and Parmaco has developed know-how on the optimum tray materials on which the MIM parts are placed in the sintering furnace.

In addition there are three front loading custom designed vacuum furnaces used for sintering stainless steels, and the company prides itself on its acquisition of an Elnik Systems combination debind and vacuum sinter furnace. The Elnik furnace provides temperature control accuracy to within +/-5°C in the six zones around the retort and can process a variety of metal/binder mixtures in a one-step debinding and sintering cycle. This is achieved through the use of a gas-tight refractory metal retort with a gas management system which allows laminar gas flow to occur thereby sweeping out the evaporated binder, CO2 and water, followed by the sintering cycle in vacuum or partial vacuum. The furnace can be automatically controlled for gas flow, temperature and partial pressure.

Backing up the impressive production facilities is a machine shop with CNC milling, grinding, and calibrating equipment although it is the company’s objective whenever possible to produce MIM parts which do not require secondary operations. Heat treatment of MIM parts, plating, etc. is done by outside contractors.

The company was accredited with ISO 9001:2000 in 1998, and its quality control section is responsible for the rigorous controls at every stage of the manufacturing process with data being fed into a PC-based data collection system for future reference or cross checking. This guarantees batch-to-batch accuracy for MIM part weight and dimensions, said Breitenmoser.

Innovative MIM productsParmaco has been successful in convincing design engineers of the merits of MIM through its ability to work with them in developing the optimum designs for the MIM process, ideally eliminating or minimising secondary opera-tions. It has also demonstrated the potential of cost savings by the ability to achieve in one part design what might have


Fig. 13 A selection of parts for various industries such as locking systems, textile, medical, stepping motor gears and fire arms

Fig. 14 This print wheel is the heart of a 24 dot matrix printer head manufactured of 3% silicon iron soft magnetic alloy

Fig.11 MIM receptor part for jig saw power tool in various stages of production.

Fig.12 Functional areas of the MIM slide used in jig saw blade holder assembly.




previously required an assembly of two or more parts as outlined in some of the examples below.

Breitenmoser, however, is not complacent about the need to do even more to promote MIM technology and to educate and inform design engi-neers who still remain unaware of the potential of the process.

There is no better way of doing this than by giving design engineers examples of successful MIM applica-tions and innovations, and in this respect Parmaco is one of the few MIM producers in Europe which has been open about some of its MIM product developments.

Parmaco follows a strong Swiss tradition of precision manufacturing and as already mentioned the company is able to achieve tolerances in its MIM parts of +/- 0.3% of blueprint dimen-sions without reworking and can achieve a surface finish, without polishing, of better than Ra 3.2. Even the so-called micro-MIM parts where the weight of the parts is only in the range of 0.01 to 0.3g, Parmaco is able to offer tolerances of 0.01mm. Examples of such tiny MIM parts are given in Figs.7 and 8. Fig. 8 shows a micro-MIM high torque planet-carrier with a sun gear for planetary gear boxes used in an opening and closing mechanism of mobile (cell) phones. The high volume part could be produced as one piece by MIM instead of assembling 5 parts. This MIM part received recognition in the EPMA Awards for Excellence in 2008.

An example of where Parmaco was able to push the boundaries of MIM

technology was a part having extremely intricate shape and thin walls (Fig. 9). The part is for a mounting unit used to position a glass prism in an optical lens system in order to deflect a laser beam. The part has to work accurately under different temperatures ranging from -20°C to +50°C which required a NiFe alloy having the required coef-ficient of expansion. It has a diameter of 43mm and all cross sections are between 0.5 and 0.7mm thin. Distor-tion and uneven shrinkage in thermal debinding and sintering were the key problems that needed to be overcome in this application, which is considered to be a masterpiece of MIM capabili-ties. The part was recognised in the EPMA’s Innovation Awards in 2003.

Yet another example of Parmaco’s capacity for innovation was rewarded with an EPMA award in 2004 for a small MIM part used in a newly introduced nut tightener system for special self drilling flat head screws for façade construction (Fig. 10). In comparison to the machined part which it replaced, MIM provided an 85% cost saving to the customer. The part is made from Fe-7Ni low alloy steel sintered at 1200°C to >7.8 g/cm3 density, and it has to survive 2000-5000 nut tightening operations.

The staying power of MIM was demonstrated through Parmaco’s long standing relationship with power tool producer Festool, which gave the company its second MIM part for a jig saw power tool model back in 1993. Breitenmoser stated that in 1999 Parmaco became involved in the devel-

Fig. 15 MIM housing cover made from 316L stainless steel for a sensor casing. (As presented in the EuroPM2009 keynote paper “Key Areas for Development in PM Technology”, Dr Olle Grinder, PM Technology AB, Sweden)

opment of the new PS300 jig saw model which was introduced to the market in 2001 and which was to include two MIM parts in the jig saw blade holder assembly. The two MIM parts used in the PS300 jig saw holder assembly are the receptor shown in different stages of production in Fig. 11 and the slide whose functional requirements are shown in Fig. 12. The MIM receptor weighs 10.28g and is made from 7%NiFe whereas the MIM slide weighs 6.37g and is also produced from the 7%NiFe alloy powder. This part is coined to achieve the required dimensional tolerances. Key to the success of MIM in this application was the good sliding characteristic of the slide part and the fit of the MIM slide in the receptor. Both parts are case hardened.

The final examples of successful applications developed by Parmaco are shown in Figs. 13 to 15. Fig. 15 is a MIM housing cover made from 316L stainless steel for a sensor casing. It is very thin walled and therefore distortion was a critical issue. The large diameter is made to hold an O-ring and must fit tightly into a tubular sensor casing also made of stainless steel. The spring latch on the large diameter secures the electrical contact between housing and cover. The moulded thread on the upper side of the housing cover allows for securing an air tight connector to the device. This casing cover is just one of a variety of casings Parmaco is producing.

Georg Breitenmoser is confident that Parmaco will continue to achieve above average industry growth in the coming years, and given that the company has almost outgrown its present facilities in Fischingen there are plans to establish a new purpose built larger MIM facility nearby. Whilst the land for the plant has been purchased, the timescale for the move is as yet not fully clear; however it is expected to happen within the next year or two. PIM International wishes the company well in its move and looks forward to a revisit in the not too distant future to report on progress.

ContactGeorg BreitenmoserParmaco Metal Injection Molding AGFischingerstrasse 75, CH-8376 Fischingen, Switzerland Tel: +41 71 977 21 41Fax: +41 71 977 21 22Email: [email protected]



PIM in Korea

PIM in Korea: A review of technology development, production and research activities

Thanks to South Korea’s status as one of the fastest growing economies in the world, the country’s PIM industry has become an important force in both component production and R&D. Dr. Seong-Jin Park and Dr. Yong-Jin Kim present a review of the development of PIM in this, the largest of Asia’s ‘Tiger’ economies, and profile a number of the leading part producers. The direction of future R&D work is also addressed.

Korea currently produces more than 100 of the world’s leading products, ranging from electronic and IT to automotive, shipbuilding and heavy industry. Consequently, Korean industry is now moving from a focus on benchmarking itself against the rest of the world to developing and enhancing its production technologies and developing new markets through an ongoing commitment to research.

This review offers an insight into the country’s PIM business along with research activities. Much of the information provided is based on a survey undertaken covering industry, government institutes and universities.

A history of PIM technology in KoreaPowder injection moulding (PIM) was introduced in the middle of the 1980’s when PIM products were starting to be commercialised worldwide. The first PIM company in Korea was Hansuh MIM Tech, established in 1988 after purchasing a license from Carpenter Parmatech Corporation. During this

period several researchers returned to Korea to assist and promote the research and development needs of PIM. These researchers included Dr Woon-Hyung Baek, Dr Sang-Ho Ahn and Dr Byung-Ok Rhee.

As the first fruit of their efforts, the ADD (Agency for Defence Development) granted a four year PIM research and development project in 1991, followed by a nine year research program called G7, which was supported by the Korean Ministry of Science and Technology.

The Research Institute of Industrial Science and Technology (RIST, Dr. Sang-Ho Ahn), Pohang University of Science and Engineering (POSTECH,

Prof. Tia-Hun Kwon), Hanyang University (Prof. In-Hyung Moon) and Ajou University (Prof. Byung-Ok Rhee) all participated in the G7 project, which played a vital role in developing powder injection moulding technology in Korea.

Through this project, key technolo-gies from binder system development, mixing, rheological characterisation of feedstock through to solvent and thermal debinding, sintering and simulation tools for several different materials were developed and a large volume of research was carried out.

In addition, two PIM companies (Bestner Inc and CetaTech Inc) were initiated as a result of the G7 project.

Fig. 1 Development through G7 project; (top left) Tungsten carbide milling insert, (bottom left) W-Cu electronic package, and (right) Filling program for PIM feedstock (Courtesy Dr. Tae-Shik Yoon, Bestner Inc.)



PIM in Korea today

The Korean PIM industry was esti-mated at approximately $40 million in 2008, excluding some in-house PIM operations.

The majority of the market for PIM products is domestic, however busi-nesses frequently export components. The market is expected to grow rapidly as global awareness of PIM technology increases.

A survey of Korea’s PIM parts producers showed that many compa-nies believe that they benefit from an advanced level of technology and expertise, with companies indicating that they can manufacture using between 70-100% of current PIM technologies as available worldwide. They also believe that part quality can be favourably compared to the world’s

PIM in Korea

leading producers whilst costs remain competitive.

All Korean PIM companies have their own in-house research and devel-opment centres. On average, compa-nies have between 10-70 employees with 20% involved in research and 40% in manufacturing.

There are currently no networking activities within the Korean PIM industry, however this survey has highlighted a need for collaborations

to ensure companies can benefit from up-to-date information.

The materials used in the Korean PIM industry are primarily ferrous, with stainless steels accounting for 34% of production and iron 29%. Carbides and ceramics account for 11% each, whilst tungsten heavy alloys account for 8% of production. The balance includes tungsten-copper,

pure copper and titanium (Fig. 2) . The majority of powders used are

imported from China, Japan and the USA however many companies have their own binder systems and mixing capabilities. Powder mixers, feedstock extruders and debinding furnaces are predominately manufactured in-house or by domestic companies, while injection moulding machines and sintering furnaces (both batch type and continuous) are imported primarily from Japan and Germany.

Key PIM part producersThere are currently more than ten PIM companies in Korea, eight of which participated in this survey, as shown in Table 1.

Amphenol Phoenix Amphenol Phoenix started business as a mould maker and producer of plastic injection moulded parts in 1993. PIM was added to their production portfolio in 2004. The Chinese arm of the busi-ness was established in 2001 under the name of Hangzhou Amphenol Phoenix Telecom Parts Co Ltd, however this division does not currently produce MIM parts.

The main products produced by Amphenol Phoenix company are PIM moulds and MIM cellular phone components.

Bestner Bestner started business as a PIM parts producer in 2000 and the main customer is Hanwha Inc. Noteable products produced (Figs. 3-5) are:

A MIM military W-Ni-Fe part for a hemispheric componentA MIM micro drill produced from WC-Co and stainless steel alloyMIM IT components of 316L and 17-4PH stainless steelMIM industrial Fe-Ni partsCIM ceramic zirconia watch componentsA CIM wear resistant aluminia part.

Bestner was granted a government project to develop Fe-Ni nano-powder and MIM parts. They also have several research and development activities including binder system development, cutting tool components, ceramic lighting components and piezo-mate-rial components.

Bestner’s facilities include a 3D profilometer, density measurement, chemical analysis and rheometer. The

•

•

•

••

•

Company Year established

CEO Website

Amphenol Phoenix 1993 Alex Perrtta www.amphenolphoenix.co.kr

Bestner 2000 Tae-Shik Yoon www.bestner.com

CetaTech 2001 Young-Sam Kwon www.cetatech.com

Hansuh MIM Tech 1988 Sang-Hwan Rhee www.hansuh.com

Kinori 1973 Dong-Ho Pyun www.kinori.com

Kyerim Metal 1986 Min-Ho Chung www.krmim.com

PIM Korea 2001 Jun-Ho Song www.pimkorea.com

PIM Tech 2002 Jae-Chul Lee www.pimtech.co.kr

Fig. 2 A breakdown of the main materials processed by the Korean PIM industry

Table 1 PIM companies in Korea who participated in this survey (in alphabetical order)

‘All Korean PIM companies have their own in-house research and

development centres’



PIM in Korea

company won the Best Technology Award from the Korean Powder Metal-lurgy Institute in 2009.

CetaTech CetaTech started business as a PIM CAE simulation tool provider in 2001 (Fig. 6) and expanded to PIM part production in 2004. Customers include LG Electronics, B&L Biotech, the Agency for Defence Development (ADD) and Hanwha Inc. The main products of CetaTech are:

PIM and PM CAE simulation software (PIMsolver and PMsolver) for injection moulding, die compaction and sinteringMIM dental tips (scaling and endodontic treatment) and CIM and MIM components for dental and medical applications (Fig. 7)MIM copper components used in air conditioning unitsMIM components for military, electrode and thermal manage-ment using W-Cu and tungsten heavy alloy (WHA)MIM components used in cutting tools and IT made of WC-Co, tungsten, zirconia and stainless steel.

CetaTech has developed several dental components in collaboration with B&L Biotech and Seoul National University (Fig. 7). They have also produced PIM CAE software using the DEM (discrete element method) in collaboration with POSTECH and ADD. Other research activities include microPIM and MIM of refractory components, using tungsten, molyb-denum and alloys of these metals.

•

•

•

•

•

MIM and CIM components of dot-matrix printers made from various materialsMIM automotive stainless steel componentsMIM stainless steel medical device componentsMIM computer and IT packaging

•

•

•

•

Fig. 3 A PIM micro drill produced by Bestner

Fig. 4 A CIM alumina printer head produced by Bestner Fig. 5 Two CIM zirconia watches produced by Bestner

Fig. 6 PIMsolver filling simulation (left) and finished Y-shaped copper components used in air conditioning units (right) produced by CetaTech

Fig. 7 MIM dental tips for scaling and endodontic treatment, produced by CetaTech

Hansuh MIM Tech Hansuh MIM Tech was established in 1988 and was Korea’s first PIM company. Customers include Samsung Electronics, LG Electronics, WeP, Citizen, Avery, Woojin Alphas, ADMo-tech, and S&T Daewoo. The company’s main products (Fig. 8) include:

Fig. 8 A selection of MIM parts produced by Hansuh MIM Tech



Fig. 12 Key management staff at Kinori, left Managing Director Mr. Nam-Woong Kim, centre, CEO Mr Dong-Ho Pyun, and right, Director of R&D Center Mr. Jung-Shik Park

PIM in Korea

components made from various materialsOther MIM and CIM components for air tools, connectors, instru-ments, texture machines, guns, hair blades and door locks.

Kinori Kinori started business as an elec-tronics parts producer in 1973 and extended production to include PIM

•

in 2004 (Figs. 10-12). The company opened a separate CIM division in 2008 specifically for the production of dental components.

The MIM division has ten injection moulding lines and five sintering lines, enabling an output capacity of three million parts per month. The CIM divi-sion has two injection moulding lines and two sintering lines producing ten thousand parts per month. Customers

Fig. 10 Production facilities at Kinori, including, from top, feedstock production, pelletising, injection moulding and the debinding and sintering area

Fig. 11 Various high purity translucent alumina and zirconia CIM components produced by Kinori

Fig. 9. Views of the production facilities at Hansuh MIM Tech. Left a bank of injection moulding machines, centre and right, debinding and sintering furnaces

include LG Electronics, Samsung Techwin and Hanwha.

The main products produced by Kinori are:

MIM parts for cellular phone components (hinge and key plate)MIM parts for digital camerasMIM parts for fibre optic commu-nication modulesStainless steels, Fe-Ni, WC, W-Cu CIM parts for cellular phonesCIM parts for translucent orthodontic bracketsCIM parts for abutment of implantsAluminia and zirconia for CIM materials.

Kinori has been involved in a major government funded project to develop optical and ceramic materials and components for metal halide lamps (PCA tube-polycrystalline arc-tube) with a budget of $1.3 billion, supported by KEMCO (Korea Energy Management Corporation).

Other research and development activities include development of cellular phone components, debinding processes using supercritical fluid, microPIM, medical applications, automotive parts, ink-jet printer heads and the housing of optical communica-tion devices.

Kyerim Metal Kyerim Metal started business in 1986 as an electronics parts producer and extended to produce PIM parts in 1988. Parts produced include:

MIM parts for cellular phone componentsMIM parts for automotive componentsMIM parts for medical devicesMIM parts for military applicationsMIM parts for industrial machinery.

•

••

•••

•

•

•

•

••

•



PIM Korea PIM Korea started business in 2001 as a PIM parts producer and acquired the PIM company Raphidus in 2008. Customers include Samsung Elec-tronics, Callaway, Motorola, Mando, TYCO, BorgWarner and Poongsan. Their main products are:

MIM parts for automotive compo-nents including turbocharger componentsMIM parts for cellular phone components including hinges, keys and buttonsMIM parts for medical devicesMIM parts for military applicationsMIM parts for golf componentsMIM parts for industrial machineryStainless steels, tool steel, W heavy alloys and Cu for MIM materials.

Total production comprises 50% automotive components, 20% for cellular phones, 20% for electronic devices and 10% other. Research and development activities within PIM Korea include the development of automotive components, microMIM technology and MIM for non-ferrous materials.

Facilities allow for high temperature tensile testing, hardness testing, an X-ray inspection system, 3D profilometer and optical microscopy.

PIM Tech PIM Tech started business as a PIM parts producer in 2002. Customers include Samsung Electronics and LG Electronics. Production includes:

MIM parts for cellular phone componentsMIM parts for WC machining componentsMIM parts for military applicationsMIM parts of Ti and Ti alloys.

Research and development activitiesThe key research centres in Korea are the Agency for Defence Development (ADD, Dr Woon-Hyung Baek), Korea Institute of Ceramic Engineering and Technology (KICET, Dr Tae-Soo Kwak and Dr Ho-Yong Shin), Korea Institute of Materials Science (KIMS, Dr Jung-Ku Lee and Dr Yong-Jin Kim), Korea Institute of Science and Technology (KIST, Dr Yong-Ho Kim,

•

•

••

••

•

•

•

••

PIM in Korea

Dr Youn-Woo Lee and Dr Jong-Sung Lim) and Korea Institute of Industrial Technology (KITECH, Dr Jung-Jin Kang and Dr Chul-Jin Hwang).

All of the above are government funded institutes. ADD, KIMS and KITECH primarily focus on the development of MIM, while KICET and KIST predominately focus on the development of CIM including zirconia, aluminia and other ceramics. Recent research activities include:

The development and commer-cialisation of a scaler tip made from 17-4PH stainless steel with a special mould designThe development of a MIM high precision component using nano-scale powdersThe development of a debinding technology for MIM using supercritical CO2

•

•

•

The development of a zirconia component using CIM, such as a watch case or cellular phone housingThe development of optical ceramicsThe development of a national materials database for powdered metals, called ‘Metals Bank’.

The majority of these research activities involve collaboration with universities including Ajou University (Prof Byung-Ok Rhee), Hanyang University (Prof Young-Do Kim and Prof Jae-Sung Lee), Korea Aerospace University (Prof Tae-Gon Kang), POSTECH (Prof Tai-Hun Kwon and Prof Seong-Jin Park), Sokang University (Prof Jong-In Lim) and Yunsei Univer-sity (Prof Chang-Ha Lee).

Additionally the Korean Government supports the government institutes

•

•

•

Fig. 13 Quality inspection of MIM turbocharger parts at PIM Korea

Fig. 16 Injection moulding machines for mass production at PIM Korea

Fig. 14 A continuous sintering facility at PIM Korea

Fig. 15 A selection of turbocharger components produced by PIM Korea



PIM in Korea

binder separation with particle size effect and the development of its modelling and simulationThe investigation into magneto-rheological behaviour of magnetic powder and binder mixtures and the development of magnetic PIM components with tight control of alignmentThe historical integration of devel-oped simulation tools including mixing, injection moulding, debinding and sinteringThe development of multi-scale simulations for nano-scale tungsten powdersThe development of a mate-rials database and materials informatics.

A very successful joint workshop between the USA and Korea took place in March 2009 at Lake Buena Vista, Orlando, Florida, supported by the NSF (National Science Foundation, USA) and KRF (Korea Research Foundation). The title of the workshop was “Work-shop on Scientific Issues for Medical and Dental Applications of Micro/Nano Powder Injection Moulding: Moulding, Sintering, Modelling and Commercial Applications.” The speakers consisted of seven Americans, four USA-Korean, six Koreans and four international with 64 participants in total. Korean researchers are keen to pursue active international collaborations with support from both the government and industry (See Powder Injection Moulding International, Vol.3. No.2, p.21-31 for a complete workshop report).

Outlook for PIM technologyThe driving force of future growth within the PIM industry in Korea will come mainly from big group companies such as Samsung Electronics, LG Electronics and the Hyundai-Kia Motor company. The design engineers in such companies are aware and well educated about PIM so adoption of this process in their components will keep increasing. In addition, these big companies will contribute to the export market as well as the domestic market for PIM. The second driving force will come from government institutes. In military science and research in aerospace and nuclear engineering, the demand for refractory materials is expected to increase as, for example, rocket nozzles, engines, armour, tung-

•

•

•

•

Research activities in modelling and simulation: Multiscale simulation

Fig. 18 Research activities in modeling and simulation. (Courtesy Dr. Seong-Jin Park, POSTECH)

Fig. 17 Research activities in modeling and simulation (Courtesy Dr. Seong-Jin Park, POSTECH)

Research activities in modelling and simulation: Historical integration

enabling PIM companies to become involved in this research. Typically, Korean PIM companies will devote approximately 20% of all employees to work in the areas of research and development. In 2010 the total invest-ment dedicated to research is expected to be about $10 million.

Based on the survey results

returned from researchers and profes-sors, the following topics are important for future PIM research in Korea:

The development of micro-MIM components for a medical applica-tion incorporating a 50µm or less pattern (Figs. 19, 20)The investigation into powder-

•

•



PIM in Korea

sten-based alloys and other systems are produced using PIM. Additionally, the use of PIM within the medical device industry looks set to rise as the demand for multi-scale components with micro-patterns made out of bio-compatible materials, increases.

The authorsSeong Jin Park, PhDMechanical EngineeringPOSTECHSan 31 Hyoja DongPohang, Kyungbuk 790-784South KoreaTel: +82 54 279 2182Email: [email protected]

Professor Park is the author of 220 articles, 6 books and book chapters, and 4 patents and has been active in PIM for over 10 years. He conducts research on simulation of PIM and related material property characterisa-tion of PIM.

Yong-Jin Kim, PhDKorea Institute of Materials Science66 Sangnamdong Changwon, Kyungnam 641-010, KoreaTel: 82-55-280-3527Email: [email protected]

Dr. Yong-Jin Kim received his PhD degree from Korea Advanced Institute of Science & Technology (KAIST), Korea in material science engineering. Since

1987 he has worked with the Korea Institute of Materials Science (KIMS) where he is conducting research in the field of powder metallurgy to develop advanced materials. The main research topics include fine powder produc-tion via the atomisation process, the

development of new PM steels for high density application, and the develop-ment of PM Al, Ti alloys and compos-ites for light weight applications.

Fig. 19 Hierarchical structured stainless steel microMIM part with micro pattern of 50µm (Courtesy Dr. Young-Sam Kwon, CetaTech)

Fig. 20 Hierarchical structured zirconia microCIM part with micro pattern of 100µm. (Courtesy Dr. Young-Sam Kwon, CetaTech)

www.pim-international.com

The largest on-line resource for the PIM industry

• Market & sector reviews • Research • Applications • Materials • Processing • Company visits

Instant access to features, technical papers and reports published in Powder Injection Moulding International

Instant access to features & technical papers

Powder Injection Moulding International’s

PDF StorePDF Store



Titanium powder injection moulding: Ti-PIM



Looking into a MIM furnace

Looking into a MIM furnace: Understanding debinding and sintering using mass spectrometry

By coupling a mass spectrometer to the exhaust system of an industrial scale furnace, researchers have gained a detailed insight into the changes and reactions that take place during the critical debinding and sintering stages of the MIM process. Thomas Hartwig and Renan Schroeder report their initial findings.

Quality assurance for the debinding and sintering stage of the powder injection moulding (PIM) process is difficult and not very elaborate. The problem is that one cannot really look into furnaces and see what is going on. This situation has been improved by connecting a mass spectrometer to the exhaust system of a MIM batch furnace. The spectra show clearly at what temperatures changes take place and allow a valuable insight into the processes.

IntroductionA critical step in furnace monitoring is the composition of the gas atmosphere during debinding and sintering of powdered precision parts. The concen-tration of reactive compounds carried into, or produced, in the furnace may be considered a main concern for all available gas conditions. The evolution of these products can greatly alter process effectiveness and material chemistry.

A straightforward control of the atmosphere may reduce cycle times and prevent and help to understand undesirable aspects occurring during MIM processing like varying carbon level. Unfortunately, as of today, there is hardly any opportunity of looking into a MIM furnace and identifying the gas atmosphere variation online. Dew point

sensors are often used, sometimes sensors for the detection of hydrocar-bons are introduced. In some studies [1, 2], mass spectrometry has been applied in a laboratory scale aiming at understanding sintering of PM parts.

Fraunhofer IFAM has connected a quadrupole mass spectrometer directly to a large industrial debinding and sintering batch furnace. This ensures that the measured atmos-

phere evolution is much closer to the reality of an industrial MIM plant than laboratory furnace trials could offer. The gases are monitored inline directly underneath the furnace chamber, as schematised in Fig. 2. By means of coupling a mass spectrometer to a real MIM furnace, the influence of powder, binder and process conditions (gas flow, heating rates, isothermal holdings, gas composition, etc.) on the

Fig. 1 The Elnik debinding and sintering furnace (left), located at IFAM’s MIM laboratory in Bremen




atmosphere evolution can be observed. Furthermore, the intervals of occurrence for thermo-activated reactions such as binder degradation, reduction/oxidation processes, carburisation/decarburisation and impurities evolution (water, nitrogen, hydrogen, etc.) are also well identified.

In this paper, the results obtained on processing tensile test specimens made of Fe-2Ni with a polyamide based binder in different atmospheres are presented, showing the effect of the gas atmosphere on the carbon content in the sintered parts.

Experimental ProcedureMass spectrometryA quadrupole mass spectrometer GAM 200 of IPI GmbH was connected to a one step debinding and sintering MIM furnace ELNIK 3001 by a capil-lary heated to about 300°C in order to prevent premature condensation of gaseous products of the binder decomposition. During the process a

continuous sample is being taken from the gas stream of the furnace directly below the furnace chamber.

In the mass spectrometer the gas is ionised and then separated according to the atomic masses of the compounds. Normally, also fragments of the initial ions are being created and then analysed. For example, Methane has the chemical composition CH4. Thus, the mass spectrum of methane will show all masses from 16, from the ionised molecule CH4

+ via mass 15 for CH3

+, mass 14 for CH2+ and mass

13 for CH+ to mass 12 for C+. In a given gas mixture the various substances are identified by their characteristic fragmentation spectrum. As can be seen in Table 1 [3], these spectra may well overlap and make interpretation of the analysis difficult. For example, ammonia overlaps with water on ions of 17 amu and 16 amu as well as with methane on 16/15/14 amu. The analysis of carbon monoxide CO in nitrogen is only possible by monitoring

atomic mass 12 as mass 28 will be dominated by N2

+.In the study, two possibilities to

perform the analysis, analog scans and multiple ion detection were generally used. In the analog scans, seen in Fig. 3, all masses in a given range are scanned. This may take several minutes but one gets a complete picture of all masses in the chosen range. When all the expected products are known or only special products are of interest, then it is possible to limit the detection to certain masses which are monitored continuously (Fig. 4), called Multiple Ion Detection (MID). In the study presented here we monitored various ions that had proved to be important by preliminary experiments and also scanned the whole range of masses up to mass 100 once every 4.5 minutes in order to make sure that no products were missed.

Experimental debinding and sinteringSamples made from Fe-2Ni with a polyamide based binder were supplied by a MIM producer after solvent extrac-tion. They consisted of Carbonyl iron powder BASF grade OM and CC plus 2% of fine nickel.

2.5 kg of the parts were used for each of the experiments. The debinding and sintering cycle consisted of the following steps:

heating with 3 K/min to 600°C, holding for 90 minutesheating with 5 K/min to 1200°C, holding for 60 minutesfurnace cooling.

The pressure in the furnace was kept at 800 mbar and the gas flow was 20 l/min at all times. The same sintering cycle was performed in pure hydrogen, in pure argon and in mixtures of 75%, 50% and 25% H2, the rest being Ar.

Carbon analysis in the sintered samples was performed using a LECO CS444. Each sample was analysed three times.

•

•

•

Products Mass Unit (amu) Products Mass Unit (amu)

Hydrogen (H2) 02 Ammonia (NH3) 17, 16, 15, 14

Nitrogen (N2) 28, 14 Carbon Monoxide (CO) 28, 12

Argon (Ar) 40, 20 Carbon Dioxide (CO2) 44, 16, 12

Oxygen (O2) 32,16 Methane (CH4) 16, 15, 14, 13, 12

Water (H2O) 18, 17, 16 Hydrocarbons (CxHy) 26, 27, 28, 29, 41, 42, 43, 44, 50, 55, 56

Table 1 Expected gas specimens and their fragments, the unit being atomic mass units

Gas inH2 - N2 - Ar

RETORT ZONE

Samples

Laminar Gas Flow

Gas out

Gas analysis

Vacuum Pump

Mass Spectrometer

Fig. 2 Schematic drawing of the furnace and mass spectrometer connection




Results and discussionsWe determined several steps of gas evolution starting with carbon dioxide desorption which takes place at around 300°C, followed by binder decomposi-tion combined with some reduction reactions resulting in the evolution mainly of hydrocarbons and water, continuing with methane, CO2 and CO being produced from binder, powder and gas. At high temperatures, again CO and water are produced from the samples already becoming fairly dense. The temperatures, reaction products and possible underlying reactions are summarised in Table 2 and will be discussed in detail in coming publications.

Fig. 5 shows the spectrum of mass 27 as well as the sample temperature as a function of cycle time for the different gas atmospheres. Mass 27 stands for the ion C2H3

+ and was seen to represent the binder decomposition. What can be seen is that the debinding starts earliest in pure hydrogen. With reduced hydrogen activity the start of the reaction is moved to higher temperatures. Also the amount of C2H3

+ removed from the samples is decreasing with decreasing hydrogen concentration in the atmosphere as can be seen from the integral under the respective curves. The debinding under 100% argon only starts at about 500°C but exhibits a similar intensity as for pure hydrogen. It also continues well into the debinding hold at 600°C. We believe that this variation in intensity represents the completeness of the debinding which is supported by the carbon analysis given in Table 3.

Fig. 6 presents the corresponding intensity of the signal for mass 16 during the experiments. As can be seen from Table 1, mass 16 can represent water, CO and CO2 (O

+), ammonia (NH2+)

as well as methane (CH4+). Comparing

this figure with the behaviour of the other signals for these reactive compounds we found it probable that the first series of small peaks are caused by an overlap of all of these compounds. The amount of these prod-ucts diminishes with the concentration of hydrogen and they can hardly be found under pure argon as they involve hydrogen in the underlying reactions. The signals starting from about 2.5 hours cycle time, corresponding to roughly 500°C and going up to almost 5.5 hours/ 700°C, were found to be caused by the evolution of methane and

Fig. 4 Typical mass spectrum obtained via MID mode

Fig. 5 Mass spectrum for atomic mass 27 (C2H3+) as well as the process temperature

as a function of process time for the different gas atmospheres

Fig. 6 Mass spectrum for atomic mass 16 as well as the process temperature as a function of process time for the different gas atmospheres. The arrows represent the assumed molecules causing the signal

Fig. 3 Typical mass spectrum obtained via analog scan: The largest peak stands for hydrogen (2 amu). The other signals are dominated by hydrocarbons produced during binder decomposition. One can see various fragments from C1 to C7 hydrocarbons as well as some water (18 amu)




For in-depth coverage of the PIM industry....It costs only £95 to benefit from more than 250 pages of exclusive news, special reports and technical papers each year. Subscribe today using the form on page 71

small amounts of CO. In this phase of the cycle the remaining binder and the carbon in the iron powder reacts with hydrogen to produce methane. This reaction is fastest and most complete under pure hydrogen and leads to complete decarburisation of the MIM parts (Table 3). The lower the hydrogen concentration the less this reaction occurs, under pure argon it cannot be detected at all. The methanisation reaction finishes shortly after the end of the isothermal hold. This is not caused by the completion of the relevant reaction as can be seen from the carbon content in these samples (Table 3). It is assumed that this effect is caused by the dissolution of the carbon into the gamma iron around the phase transition of alpha- to gamma-iron.

Table 3 presents the carbon content of the samples sintered in the different atmospheres. The less hydrogen in the debinding atmosphere the higher the carbon content. This carbon content has to be compared with the amount of carbon in the starting powder which is in the range of ≤0.35%. If there is no hydrogen at all under pure argon then the carbon level remains more or less constant.

Low concentrations of hydrogen

Condition 100% H2

75%H2

25%Ar 50%H2

50%Ar25%H2

75%Ar 100% Ar

%C 0.006 0.293 0.552 0.647 0.321

Table 3 Carbon content in the sintered parts processed under different gas atmospheres

lead to a drastic increase of the carbon content, an effect that cannot be explained, yet. One possibility is that the hydrogen supports the removal of the coating of the iron powder with hydroxides and oxides. The resulting clean surface can then react with the residual binder.

It is interesting to see that while Fig. 5 suggests that all debinding is already completed before the start of the debinding hold, Fig. 6 clearly shows that the hold may well be necessary, depending on the required carbon content of the final part. Here, the mass spectrometry may act as a control instrument to adjust the cycle time to the minimum required duration while still achieving the material quality specified for the given part.

ConclusionsMass spectrometry allows us to look into the reactions occurring between powder, binder and variables for processing of MIM parts in larger industrial furnaces. The investigation of a wide range of different powders and binders will certainly contribute towards optimisation of debinding and sintering in MIM production plants. Processing time, carbon control and

adequate processing variables selec-tion are features that Fraunhofer IFAM has already been studying with this new equipment.

References

[1] Danninger, H.; Gierl, C.: New Alloy Systems for Ferrous Powder Metal-lurgy Precision Parts. In: Science of Sintering, 40 (2008) 33-46.[2] Danninger, H.; Wolfsgruber, E.; Ratzi, R.: Gas Formation during Sintering of PM Steels Containing Carbon. In: Proceedings of the Euro PM’97 on Advances in Structural PM Component Production, p. 99, Munich, Germany, 1997.[3] MacLafferty, F. W.; Turecek, F.: Interpretation von Massenspektren. Spektrum Academischer Verlag. Germany, 1995.[4] Hryha, E.; Cajkova, L.; Dudrova, E.; Nyborg, L.: Study of Reduction/Oxida-tion Processes in Cr-Mo Prealloyed Steels during Sintering by Continuous Atmosphere Monitoring. In: Proceed-ings of Euro PM Congress + Exhibition, v. 1. Mannheim. Germany. 2008.

ContactsDr Thomas Hartwig IFAM, Fraunhofer-Institute for Manfacturing and Advanced Materials, Powder Technology Lab.BremenGermanyTel: +49 421 2246 156Fax: +49 421 2246 300Email: [email protected]

Renan SchroederMaterials LaboratoryFederal University of Santa CatarinaFlorianópolisSanta CatarinaBrazilEmail: [email protected]

Temperature Range (ºC)

Gas Products Reactions

200 - 300250 - 520250 - 520

CO2

H2OCxHy

Desorption Reactions [4]Binder decomposition and reduction processes

420 - 700 CH4 Methanation (in H2)

910 - 1200 H2O CO

Reduction Processes

Table 2 Summary of obtained gas products from grade CC sintered under H2

Powder Metallurgy - A Global Market Review

Essential information for anyone with an interest in the current state of the global PM industry

www.ipmd.net

‘Powder Metallurgy - A Global Market Review’ presents key statistical data highlighting the current state of the PM industry including both part and powder production.

The report includes detailed sector reviews for PM materials covering Ferrous PM, High Alloy PM Steels, Copper and Copper-base, Hardmetals/Cemented Carbides, Diamond Tools, Refractory Metals and Powder-Based Magnets.

Two additional inset features review PM’s special relationship with the automotive industry and the growing use of Metal Injection Moulding (MIM).

This 10,000+ word document features 22 tables and 23 charts. Sections of this review include:

• Manufacturing takes a hit as the global economy dives into recession

• MARKET SECTORS FOR PM MATERIALS - Ferrous PM Materials - High Alloy PM Steels - Copper and Copper-base - Cobalt- Tungsten- Molybdenum - Tantalum - Niobium/Rhenium - Hardmetals/Cemented Carbides - Diamond Tools/CBN Tools - Powder-based Magnets

• REGIONAL MARKETS- North America- Europe - Asia/Oceania

• SPECIAL FEATURE: MIM FOCUS Metal Injection Moulding (MIM) growth slows in 2009

• SPECIAL FEATURE: AUTOMOTIVE FOCUS Global recession hits auto output

International PM Directory

PDF StorePDF Store

Price: £125

PDF format, 24 pages, 10,186 words

Market review originally published in the IPMD 14th Edition 2010-2011

Author: Bernard Williams, PM Consultant, Shrewsbury, United Kingdom

To purchase your copy and instantly download the PDF visit: www.ipmd.net/pdf

market review advert.indd 2 3/1/2010 3:59:16 PMMarch 2010 Front Section.indd 46 3/5/2010 1:42:55 PM


Powder Metallurgy - A Global Market Review

Essential information for anyone with an interest in the current state of the global PM industry

www.ipmd.net

‘Powder Metallurgy - A Global Market Review’ presents key statistical data highlighting the current state of the PM industry including both part and powder production.

The report includes detailed sector reviews for PM materials covering Ferrous PM, High Alloy PM Steels, Copper and Copper-base, Hardmetals/Cemented Carbides, Diamond Tools, Refractory Metals and Powder-Based Magnets.

Two additional inset features review PM’s special relationship with the automotive industry and the growing use of Metal Injection Moulding (MIM).

This 10,000+ word document features 22 tables and 23 charts. Sections of this review include:

• Manufacturing takes a hit as the global economy dives into recession

• MARKET SECTORS FOR PM MATERIALS - Ferrous PM Materials - High Alloy PM Steels - Copper and Copper-base - Cobalt- Tungsten- Molybdenum - Tantalum - Niobium/Rhenium - Hardmetals/Cemented Carbides - Diamond Tools/CBN Tools - Powder-based Magnets

• REGIONAL MARKETS- North America- Europe - Asia/Oceania

• SPECIAL FEATURE: MIM FOCUS Metal Injection Moulding (MIM) growth slows in 2009

• SPECIAL FEATURE: AUTOMOTIVE FOCUS Global recession hits auto output

International PM Directory

PDF StorePDF Store

Price: £125

PDF format, 24 pages, 10,186 words

Market review originally published in the IPMD 14th Edition 2010-2011

Author: Bernard Williams, PM Consultant, Shrewsbury, United Kingdom

To purchase your copy and instantly download the PDF visit: www.ipmd.net/pdf

market review advert.indd 2 3/1/2010 3:59:16 PMMarch 2010 Front Section.indd 47 3/5/2010 1:42:59 PM

Powder Injection Moulding International March 201048 Vol. 4 No. 1

Global PIM Patents

The following abstracts of PIM-related patents have been derived from the European Patent Organisation databases of patents from throughout the world. Full information on individual patents (in the language of the country) is available through the PIM International editorial office.

WO2007109300 (A2)RECYCLABLE BINDERS FOR METAL CASTING MOULDS AND FOR INJECTION MOULDING OF METAL AND CERAMIC PARTSPublication date: 2007-09-27Inventor(s): C. Dilek, etal Wayne State University, USARecyclable mould for forming a metal or ceramic article by injection moulding is disclosed. The recyclable mould comprises base material particles mixed with a binder material binding the base material particles to define a prede-termined shape having a cavity in which the metal article is to be moulded. The injection moulded metal or ceramic part comprises mixing fusable metal or ceramic powder with a binder mate-rial to form a solidified green body. The binder mate-rial is soluble in carbon dioxide and comprises a tert-butylated aromatic or sugar acetate.

FR2896712 (A1)POWDER PRECURSOR CONTAINS hIGh METAL CONTENT POWDER, INORGANIC COLOURED PIGMENT AND BINDING AGENT FOR PRODUCTION OF COMPONENTS BY INJECTION MOULDINGPublication date: 2007-08-03Inventor: G. Baret, DGTec Soc. Par Actions Simplifi, FranceA powder precursor is for produc-ing a high metal content component by injection of the precursor into a mould, heating it in the mould and, after removal from the mould, by heat treatment of the moulded component to sinter the metal grains. The precur-sor is made up of a powder with a high metal content added to an inorganic coloured pigment in the form of a powder with a granulometry of between 20 nm and 500 nm and a linking agent. An independent claim is also included for the component obtained using the powder precursor

US2007202000 (A1)METhOD FOR MANUFACTURING GAS TURBINE COMPONENTSApplication date: 2007-08-30Inventor(s): G. Andrees, etal, GermanIn a method for manufacturing gas tur-bine components by powder injection moulding and several moulded articles are joined together by a diffusion proc-ess during sintering to manufacture a component. The moulded articles to be joined together are preferably brought into surface contact, especially into form-fitting surface contact, at least during sintering on sections that are to be joined together. A pressure is applied to the moulded articles to be joined together during sintering.

WO2007098739 (A1)PRODUCTION OF A SEALING SEG-MENT, AND SEALING SEGMENT TO BE USED IN COMPRESSOR AND TURBINE COMPONENTSApplication date: 2007-09-07Inventor(s): R. Meier, et al MTU Aero Engines Gmbh, GermanyThe sealing segment comprises at least one first moulded article as a basic element and at least one second moulded article as a brush layer, which has less abrasion resistance than the first moulded article, the first and the second moulded article each being produced using a powder injection moulding process, and joined during sintering.

CN101037579 BINDER FOR POWDER INJEC-TION FORMING Publication date: 2007-09-19 Inventor: LIANG S. T., UNIV CENTRAL SOUTh UNIVERSITY China [CN] The invention discloses a binder for powder injection moulding prepared by mixing paraffin, high-density polyeth-ylene, ethylene acetate copolymer, and modified dibutylphthalate. Compared with existing binders the new method uses low cost and non-toxic raw mate-rial. The low molecule component paraffin with its good flowability can effectively reduce feedstock viscos-ity in MIM and increases mold filling property. High molecular polymers

Global PIM Patents

March 2010 Technical Papers.indd48 48 3/5/2010 1:22:10 PM

March 2010 Powder Injection Moulding International 49Vol. 4 No. 1

Global PIM Patents

acts as framework to maintain shape of blank during debinding. Addition of the modified dibutylphthalate improves mixing, reduces defects and increases mechanical property of final product.

EP1857244 (A1)COOLED MOULD INSERT FOR INJECTION MOULDSPublication date: 2007-11-21Inventors: G. Mai, Werkszeugbau Siegfried hofmann, GemanyCooled insert for an injection mould, comprising an elongated body section adjoining a shaft and/or head part, (a) is at least partially formed in a genera-tive process by melting solidified metal powder and (b) has (at least in the elon-gated section) gas cooling channel(s) a short distance behind the outer wall, having a non-circular cross-section and a smallest internal separation from the opposite internal walls of 1 mm or less. An independent claim is included for an injection moulding machine incorporating an injection mould with a cooled mould insert

JP2009176974 (A)INJECTION MOLDING SOFT-MAGNETIC MATERIAL, AND SOFT-MAGNETIC KNEADING MATERIAL Publication date: 2008-01-25Inventors: J. Ezaki, S. Takemoto. Daido Steel Co Ltd, JapanThe invention relates to an injection moulding soft-magnetic material and a soft-magnetic kneading material which reduce magnetic core-losses. The soft-magnetic material comprises Fe-7-9 mass% Si powder with an organic high-molecule binder material which also contains a soft-magnetic material.

CN101235265 (A)BINDER AND FEEDSTOCK FOR METAL INJECTION MOULDING Publication date: 2008-01-25Inventors: W. Junwen, F. Zhongfeng (China)The invention relates to a low cost binding agent and preparation of feed-stock for MIM. The binder comprises thermoplastic elastic compounded rubber, industrial paraffin, high density polythene HDPE, propene polymer PP and geoceric acid, and the feedstock is prepared by mixing according to mate-

rial ratio, heating extrusion, cooling disintegration and vacuum packaging. The solid loading of the feedstock is over 60%.

JP2009179488 (A)INJECTION MOULDING OF ALUMINUM NITRIDE SINTERED COMPACTPublication date: 2008-01-29Inventors: K. Goto. K. Watanable Tokuyama Corp; Sun Arrow Kasei Co Ltd (Japan)Provides an aluminium nitride compo-sition for injection moulding, which has high fluidity and excellent debinding properties, and has satisfactory shape retainability even in the case of a thin moulded body having a wide surface area or an aluminium nitride moulded body with a complicated shape.

WO2009098036BIOCOMPATIBLE COMPONENT MADE BY POWDER INJECTION MOULDING Publication date: 2008-02-08Inventor: A. Rota, P. Imgrund. Fraun-hofer Ges. Forschung (Germany), EMPA (Switzerland)The invention relates to a method for producing components that have at

least partially biocompatible surface areas. A mixture from a biocompatible powder material and a binder is injec-tion moulded, debound and sintered. The powdery biocompatible material used is a mixture that consists of a particle size of between 700 nm and 50µm and of 5% by weight to 50% by weight of particles of a particle size of less than 700 nm.

US2009224442METhOD OF MANUFACTURING TRANSLUCENT CERAMIC ORThODONTIC COMPONENTPublication date: 2008-03-05M. Sakata, J. hayashi. Seiko Epson Corp. (Japan)A method of manufacturing a translu-cent ceramic used in orthodontics by powder injection moulding is provided. The method comprises: mixing a raw powder and an organic binder and kneading them to obtain a compound, the raw powder containing an alumin-ium oxide powder and a magnesium oxide powder, and the organic binder containing a first organic component and a second organic component.

JP2007278303 (A)FUEL INJECTION VALVE Publication date: 2007-10-25Inventors: h. Kado, etal. hitachi Ltd, JapanTo provide a fuel injec-tion valve wherein an anchor portion of a valve element is easily moulded and machined in such a manner that a change in the outer diameter of the anchor portion is suppressed to improve responsive-ness and assembling workability. The anchor portion is formed using MIM of a magnetic material and sintering it so that its relative density is within a range of 95-98%.



Technical Paper

Design and Manufacture of Gears with a Skin-Core Structure by Metal Co-Injection Moulding

Gears with a skin-core structure have been designed and produced using a novel metal co-injection moulding technique. The effect of skin temperature and injection velocity on the material distribution of the co-injection moulded specimens has been studied. It was demonstrated that the temperature exerts a more important influence on the phase distribution than injection velocity. The adequate selection of the processing conditions enabled an accurate control of the relative thickness of the layers of the parts.

hao he, Yimin Li*, Pan Liu, Jianguang Zhang

State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, China*Corresponding author: Tel: 86-731-88830693, Fax: 86-731-88830694Email: [email protected]

IntroductionGears are now used for a wide range of industrial applications for transmitting power or rotational force from one component to another. Modern gears are made from a wide variety of materials. Of all these, alloy steels are widely used due to their outstanding characteristics of high strength per unit volume and low cost per pound [1]. Heat treatment is often conducted after gears have been shaped in order to combine properly the toughness and tooth hardness. However, the surface treatment represents an additional step in the manufacturing cycle with the associated increase in manufacturing costs. Recently, metal co-injection moulding (co-MIM) has been described as an alternative manufacturing method for the production of this type of gear [2]. Co-MIM uses two different powder/binder mixtures which are injected into a mould sequentially, so that one mixture forms the surface layer of the component and the other forms the core. It offers the ability to

accomplish the “surface treatment” in a single process rather than post-processing procedures. In this way, the number of processing steps can be reduced, making cost-effective products feasible. This is why co-MIM has attracted growing attention in recent years.

In previous studies and flow visualisation investigations, it is found that the mechanical properties of co-injection moulded parts show a high correlation with skin/core distribution, namely the skin thickness and uniformity [3, 4]. Therefore, in co-MIM, the ability to control the material distribution is important. It is indicated in polymer co-injection moulding that the material distribution is influenced by several factors, such as the viscosities of core and skin, moulding parameters, core content and mould geometry. Very different phase distributions could be induced by viscosity differences of the two melts. Generally the most uniform skin-core structure occurs when the core has a similar or slightly higher

Fig. 1 Viscosity-shear rate data for core (a) and skin melts (b) at different temperatures

(a) (b)



shown in Fig. 1. After the extrusion granulation on a YHL04 plastic extruder, specimens were co-injection moulded on a 160 tone, twin-barrel injection-moulding machine (HTSJ160B, HaiTian Plastics Machinery Ltd, China). The combinations of moulding conditions that were used are shown in Table 1.

The geometry of the mould used was a square plate, 160×160 mm, with a thickness of 5mm and a rectangular gate with dimensions of 6×5×1 mm located at the end. Moulded parts were then sectioned and the distribution of core melt was measured both parallel (y) and perpendicular (xi, i=1, 2, 3, split the core into four parts evenly) to the flow direction, as shown in Fig.2. Skin thickness at xi can be compared to the skin thickness at position y by calculating their ratio. This is an important response since a value equal to 1 corresponds to a more uniform core extension.

ResultsCore penetration

A series of co-injection moulded plates is shown in Fig. 3. These are produced from melts with varying skin temperatures but with a constant core temperature of 158°C. In all cases, the skin-core structure is obtained without breakthrough of core material to the skin. Plus, a considerable variability in cross-section can be seen. The results of core penetration at position xi and y were evaluated as a function of skin temperature and the results are shown in Fig. 4(a). It can be seen that, as the skin temperature is gradually increased, the extent of penetration of the core melt at position y becomes less, i.e., an increase of this parameter (from minimum to maximum condition) decreases the core penetration depth at y by 12mm (8%). While in the x direction, the core penetration increases at x1 and x2 and decreases at x3. The observed results are in qualitative agreement with experimental findings in polymer co-injection moulding [6], indicating the flow behaviour of metal feedstocks in such two-phase co-injection moulding is similar to that of polymer melts.

Fig. 4(b) shows penetration depth of core melt as a function of skin velocity at a constant core velocity of 60g/s and skin/core temperature of 164°C, in which the penetration of the core melt at y decreases as skin velocity increases can be clearly seen. This effect has been described in co-injection moulding using polypropylene as a raw material by previous investigators [8]. However, an increase of this parameter only decreases y by 5mm (3%) from minimum to maximum condition, which is smaller than previously reported.

Skin uniformityWe have also considered the problem of uniformity of skin thickness. The various skin thickness ratios defined are plotted as a function of skin temperature in Fig. 5(a). At a lower skin

Technical Paper

Parameter Skin Core

Moulding temperature (°C) 152,158,164,170,176 152,158,164,170

Injection pressure (MPa) 90 90

Injection speed(g/s) 30,45,60,75,90 30,45,60,75,90

holding time(s) 3 3

Mould temperature (°C) 40

Cooling time(s) 40

Delay time 0

Table 1 Moulding conditions used

viscosity than the skin. Lower viscosity ratios between core and skin (ηcore/ηskin) will lead to a breakthrough, while higher ratios will lead to poor mould filling and nonuniform skin thickness. Important moulding parameters are injection velocity and melt temperature [5, 6]. These will affect the viscosities of the two melts, and hence the viscosity ratio. The relative content of the two melts and delay time between the first and second injection processes, are also important in tailoring properties of the moulded parts.

A good understanding of the effect of moulding parameters on the material distribution is a prerequisite for controlling the properties of components during co-MIM. Although much work has been done in polymer co-injection moulding, there are few investigations have been carried out on the relationship between moulding parameters and material distribution of metal co-injection moulded parts [7]. Since the properties of metal feedstocks are quite different from those of polymer melts, it would seem, therefore, that systematic investigations are needed. This paper reports on the attempt to manufacture gears with a skin-core structure based on the co-MIM process. It comprises two main parts. Firstly layer thickness and uniformity of co-injection moulded plates were measured as a function of moulding parameters. Two major moulding parameters, skin temperature and injection velocity, were studied. The results were analysed by taking account of the relative viscosity of the two melts. Second, gear prototypes were produced using the obtained results as a design guideline.

ExperimentalMaterials used in this study were gas-atomised 316L stainless steel powder (Osprey Metals) with an average particle size of 11.5µm and a multicomponent binder system composed of 55 wt% paraffin wax, 35 wt% polypropylene and 10 wt% stearic acid. Two feedstock formulations containing 40 and 60 vol.% of powder loading were mixed. Specimens were fabricated with the former as the core and the latter as the skin. The core material was coloured black with 1% commercial grade graphite to facilitate identification of the interface between the core and skin. The powder and binder were initially blended in a three-dimensional shaker for 30 minutes at room temperature, and then compounded in XSM1/20-80 rubber mixer at 165°C for 2h. The apparent viscosity of the powder-binder mixtures was measured using a CEAST S.P.A, Pianezza(TO) Rheo5000 capillary rheometer at temperature range from 150 to 180°C. A 1mm diameter, 40mm length die was used. The shear rate was varied between 40 to 1200s-1. Viscosity shear rate curves for the two materials at the relevant moulding temperatures are

Fig. 2 Schematic picture of the measurement of core penetration



Technical Paper

temperature of 152°C the skin thickness at x1 and x2 are larger than that at y (skin thickness at x3 is very much larger than x1 and x2, and therefore is not discussed below), resulting in a nonuniform material distribution. As temperature increases the skin thickness in x direction increases while in the y direction decreases, resulting

in a higher uniformity. This is in agreement with photographs in Fig. 3, in which we can see the core cross section, perpendicular to flow, becomes more circular at higher skin temperatures. This plot shows that a greater uniformity occurs when the skin temperature is about 158~164°C. And with further increase of skin temperature, it becomes nonuniform again because the skin thickness in the x direction becomes smaller than y, as reported by previous researchers [6].

The skin thickness uniformity plotted as a function of skin injection velocity is shown in Fig. 5(b). A similar trend can be seen as in Fig. 5(a). This plot shows that a greater uniformity occurs when the skin injection velocity is around 70~90g•s-1.

DiscussionThe influence of moulding parameters on phase distribution can be examined by taking account of the viscosity ratio, representing the primary influence of rheological properties, between the core and skin materials. A hydrodynamic interpretation of two-phase flow into moulds has been developed using lubrication Hele-Shaw flow theory [4], as follows:

vskin/vcore = (ηcore/ηskin)1/n

where vskin and vcore are the flow velocities of the skin and core melt, n is the flow behaviour index and ηcore and ηskin are the core and skin viscosities. This equation indicates that larger velocity ratios changes occur with greater viscosity ratios changes. Therefore, quantitatively describing the dependence of the feedstock viscosity on the moulding parameters is a critical first step towards explaining why moulding parameters have different effects on the material distribution.

The dependence of the feedstock viscosity on the shear rate can be expressed by a power law model [9], as follows:

η = Kγ n-1

where η is the apparent viscosity of feedstock, K is a constant to represent a viscosity at a shear rate equal to 1, and γ is the shear rate. Plotting lnη against lnγ , as shown in Fig. 6(a) and (b), the values of n and K for both the core and the skin at a temperature of 164°C can be obtained using a linear fit; this gives kcore= 292.1, ncore= 0.66 and kskin= 789.9, nskin= 0.55, the correlation coefficient for standards was >0.99. Then, the viscosities of core and skin encountered in experiments can be calculated, as well as the viscosity ratios. The calculated results gives viscosity ratio values of 0.7 and 1.15 under the condition of injection velocity of 30 and 90 g•s-1, respectively (the dependence of the injection velocity on the shear rate is shown in Appendix).

(a) (b)

(c) (d)

(e)

Fig. 3 Co-injected plates at various skin temperatures (a-152°C, b-158°C, c-164°C, d-170°C, e-176°C) and a constant core temperature of 158°C

(a) (b)

Fig. 4 Influence of skin temperature (a) and injection velocity (b) on the core penetration depth



Technical Paper

From Fig. 6, we can obtain the values of n and K at other temperatures as well. Then, the viscosities and viscosity ratios encountered at different temperatures can be obtained, as shown in Table 2. The results give viscosity ratio values of 0.49 at 152°C and 1.06 at 176°C respectively. And it can be seen clearly that the viscosity ratio change induced by temperature is much larger than that of injection velocity.

The increase in temperature can effectively decrease the viscosity of the skin feedstock, and hence increase the viscosity ratio of core to skin. Therefore, very different phase distributions were induced by temperature change, while injection velocity seemed to play no significant role.

As for the problem under which condition the most uniform skin thickness occurs. For the injection velocity, the relative viscosity of core to skin ranges from 1.06 to 1.14 (from 70 to 90g•s-1). As for the temperature, it ranges from 0.94~0.95 (from 158 to 164°C). This confirms the concept that the most uniform skin-core structure occurs when the core has a similar viscosity to that of the skin.

Manufacturing of prototype gearsPrototype gears were fabricated with Fe2Ni (good ductility) as the core and Fe2Ni1Cr (good hardenability and wear resistance) as the skin. The co-sintering behaviour of Fe2Ni/Fe2NiCr has

been reported in our previous work [10]. We have coloured the core material of some parts black to distinguish the interface. The parts were produced using a 12-cavity mould on a twin-barrel injection-moulding machine. Sintering was via a batch process in argon. Moulded and sintered parts were sectioned to observe the distribution of skin/core melts. Specific challenges were encountered in controlling the material distribution at a high content of core material. The maximum content of core material that can be injected without breakthrough is about 75 vol.%, and the thinnest skin layer thickness can be reduced to less than 0.5mm. The most uniform skin thickness occurs at the viscosity ratio values ranging from 0.98 to 1.1. By adjusting the

Fig. 5 Influence of skin temperature (a) and injection velocity (b) on skin thickness uniformity

(a) (b)

Fig. 6 Ln viscosity vs. ln shear rate of core (a) and skin (b) melts at different temperatures

Feedstock Temperature K n Viscosity

core

152 8.25 -0.61495 8.69

158 5.86 -0.35074 10.91

164 5.68 -0.33847 10.23

170 5.38 -0.32974 8.26

skin

152 8.32 -0.55688 22.34

158 6.94 -0.47937 11.6

164 6.67 -0.45138 11.54

170 6.56 -0.44335 11.14

176 6.37 -0.43054 10.33

Table 2 The calculated viscosity of the core and skin melts at different temperatures

(a) (b)



Technical Paper

relative viscosity of core to skin, a series of co-injection moulded gears with controlled skin thickness can be obtained, as shown in Fig. 7(a). The bond interface after sintering appears sound and no cracks are visible, as shown in Fig. 7(b).

ConclusionsPrototype gears with a skin-core structure have been prepared using the metal co-injection moulding technique. Influence of moulding parameters on the phase distribution can be examined by taking account of their influence on the viscosity ratio between the core and skin materials. The increase in temperature can more effectively change the viscosity ratio values, and therefore, skin temperature exerts a more important influence on the phase distribution of metal co-injection moulded parts than injection velocity. The most uniform skin-core structure occurs when the core has a similar or slightly higher viscosity than the skin. By adequate selection of the processing conditions, an accurate control of the relative thickness of the layers of the parts can be achieved.

AppendixThe dependence of the injection velocity on the shear rate for a rectangular gate can be expressed by [11], as follows:

γ=6Q/(Wh2)where Q is the injection velocity(mm3/s), w is the width, h the is

depth, corresponding to 6 and 1mm respectively in our study.

References[1] http://www.normas.com/ASM/pages/06732G.html.[2] J.R. Alcock, P.M. Logan, D.J. Stephenson, Surf. Coat. Technol.105(1998) 65-71.[3] J.L. White, H.B. Dee, Polym. Eng. Sci. 14 (1974) 212-222.[4] S.S. Young, J.L. White, E.S. Clark, Polym. Eng. Sci. 20 (2004) 798-804.[5] G. Akay, Polym. Compos. 4 (1983) 256-264.[6] R. Seldén, Polym. Eng. Sci. 40 (2000) 1165-1176.[7] K.Okubo, M.Ishida, S.Tanaka, K. Nishiyabu. PM2004. 381-387.[8] T.Nagaoka, U.S Ishiaku, T.Tomari, H.Hamada, S.Takashima, Polym. Test. 24 (2005) 1062-1070.[9] I.Agote, A.Odriozola, M.Gutierrez. Eur. Ceram. Soc. 21 (2001) 2843.[10] H. He, Y.M. Li, J. Lou, J.G. Zhang, Powder Injection Moulding International. 3 (2009) 56-59.[11] http://www.pcn.org/Technical Notes - Gates and runners.htm.

Fig. 7 Photographs of the as-moulded and sintered gear prototypes (a) and a morphology of the interface after sintering (b)

(a) (b)


Technical papers and features published in PIM International are also available for download from our website, for the full list please visit www.pim-international.com

Instant access to features & technical papers

Powder Injection Moulding International’s

PDF StorePDF Store

Missed anything?



Technical PaperTechnical Paper

A Case Study on Computational Fluid Dynamics Analysis of Micro-MIM Products

Many people are familiar with computational fluid dynamics studies for plastic injection moulded parts but little study has been undertaken in the field of micro metal injection moulded parts. Micro metal injection moulding (MIM) is a relatively new technology and many advances are progressing in production methods that increase accuracy and applicability of its use. Computational fluid dynamics studies of such methods can assist in furthering the advancement of this technology and can provide valuable information to manufacturers and consumers alike. A study on two micro-MIM manufactured test parts was done using Moldex 9.0 CFD and Rhinoceros 4.0 (with Moldex3D-Mesh plug-in software) Modelling software. The methods for realising some common problems unique to micro-MIM analysis were proposed and applied to two micro-size MIM parts to find suitable process conditions in this paper. The results of this study were used to check for production viability and to improve the design of the test parts for possible future production. An ideal set of process conditions and assumptions was found for MIM CFD analysis performed in Moldex 9.0.

Ian Andrews1, Kazuaki Nishiyabu2 and Shigeo Tanaka3

1Dept. of Industrial Systems Engineering : Mechanical Systems Course, Former lecturer2Dept. of Industrial Systems Engineering : Mechanical Systems Course, Associated professor3Taisei Kogyo Co, LTD., President

IntroductionComputational Fluid Dynamics (CFD) is the science of determining a numerical solution to the governing equations of fluid flow whilst advancing the solution through space or time to obtain a numerical description of the complete flow field of interest. CFD analysis consists of 3 main stages; Modelling and Meshing, Pre-Processing and Post-Processing. Each stage can be further split down into smaller sections. Modelling is the first stage that is undertaken with all CFD processes. This involves making 2D or 3D models of the geometry of the areas where the fluid flow analysis is required. For injection moulded parts, this usually consists of models of the part, its mould and the cooling arrangement with the mould. After modelling the geometry of the required areas, these areas are required to be split into many small areas called meshes. The many complicated equations involved in CFD are solved in each of the many small areas throughout the geometry and flow properties can be derived from the results. There are many types of mesh, each suitable for various geometries or analysis methods. Pre-processing involves using the models and meshes created and inputting the desired material properties, flow properties, temperatures, process durations etc. For injection moulding analysis, the injection machine properties such as injection pressure and packing length etc are often specified. The computation methods are also set at this stage. The type of mathematical solver, desired accuracy and various assumptions and simplification can be set here. Once all the properties and conditions are set the CFD analysis can be started. Post-processing is the final stage and is undertaken after the CFD analysis has finished obtaining a solution. In this stage the flow properties can be analysed and various images, graphs and data can be seen. This data can be used as a qualitative tool for discarding (or

narrowing down the choices between), various designs. Designers and analysts can study prototypes numerically, and then test by experimentation only those which show promise.

Whilst CFD is a very useful tool, CFD is not yet at the level where it can be blindly used by designers or analysts without a working knowledge of the numerics involved. Despite the increasing speed of computation available, CFD has not yet matured to a level where it can be used for real time computation. Numerical analyses require significant time to be set up and performed and have varying degrees of accuracy depending on flow properties and settings. CFD is an aid to other analysis and experimental tools like wind tunnel testing, and is used in conjunction with them. In particular, CFD analysis for micro injection MIM parts has not been undertaken to a great degree due to unreliable accuracy and computational resource difficulties but will become increasingly useful as production and computer technology advances. CFD analysis alone cannot be relied upon to provide all the information for the optimal process conditions and methods, but it can simplify the process greatly.

Analytical ProcedureFor this study two micro-MIM test products were analysed using Moldex 3D v9.0 and Rhino modelling software v4.0. The procedure for CFD analysis is Moldex 3D and Rhino can be split into 4 main sections; Modelling, Meshing, Pre-processing and Post-processing.

Modelling The models used in the analyses were created from blueprints and engineering drawings in Pro-Engineer and imported into Rhino



Technical Paper

4.0 in IGES file format. The geometries of the analysed parts are shown in Fig. 1. The first part was dubbed ‘Shikaku’, and is a micro-sized MIM part. The size of the part is roughly a 14.55mm square with a 7.65x10.85mm rectangular hole in the centre, a groove cut into the surface surrounding the hole, and four tapered holes of 0.2mm diameter on the top surface. The part is also very thin, with a thickness of 0.4mm and 0.2mm in the groove region. The cubic capacity of the cavity is less than 0.05cm3. The second part is a micro-sized MIM gear with the diameter of the addendum circle being 1.12mm, depth of 0.8mm and a central shaft hole with diameter 0.42mm. The cavity cubic capacity for this part is approximately 0.0005cm3.

Extremely small characteristics of the geometries, such as minor tapers and chamfers that would have had little effect on the CFD results were ignored for simplification. After importing the IGES files from Pro-E to Rhino, they were checked for anomalies and to ensure they were enclosed 3D models with no defects. Next, basic initial runner systems were modelled and attached to the cavities. Both parts were non-finalised test products and as such had no runner size/shape, gate location or cooling system associated with them. Various runner types and gate locations were tested before settling on optimal specifications for each model.

Meshing The cavities were checked again before meshing procedures were applied. Before meshing, nodes were assigned to all edges of the models, and in increased density in smaller, thinner sections of the cavity. This was done to ensure a reasonable element count across the section of the part, which affects the resolution and accuracy

of the final results derived from the analysis. Initially a standard tetrahedral mesh was applied to the cavities, holes in the mesh were repaired and bad elements were fixed. After the surface cavities were meshed, the 3D runner meshes were created automatically using the function in Rhino, which forms prism meshes for reduced computational load and speed. Both meshes were checked for connectivity, then the 3D cavity mesh was generated and its elements were auto-fixed to remove poor elements. In all cases the total model element count was kept between 0.5-0.8million so many iterations of analysis could be performed with suitable speed and accuracy. The final meshing stage involved creating a mould-base face model which was cuboids surrounding the model and runner meshes. This mould-base face was also meshed using the auto function in Rhino, and was used to represent the mould in the analysis. In total, the cavity meshes and mould base meshes included approximately 1.0-1.2million elements. The complete 3D models were then exported to Moldex 3D v9.0 for analysis.

Pre-processing and Materials In the pre-processing section, the model, process conditions and computational solver conditions are set. A new project file was created in Moldex v9.0 for each model as shown in Fig. 2. After the model was selected for analysis, the material used was specified. The material used in this study came from empirical data of material properties of Taisei Kogyo’s MIM material, SUS316L 65:35 [1]. MIM material is a polymer of metal powder and a binding element comprised of waxy plastics. The metal powder molecules form an isotropic matrix inside the binder, which is removed at a later stage, so that only metal remains forming a tough part with good material properties. Whilst the material for the analysis had the material properties of a MIM material, it is not currently possible to accurately model all of the complex flow characteristics of a MIM material, such as layer slip, compressibility and jetting. The material in the analysis had similar flow characteristics to that of a heavy plastic. After the material was set, the process conditions were set. In Moldex there are three setting types for the process conditions, two machine interface types and CAE mode. Most commercial injection-moulding CFD programs cannot accurately model micro-parts using standard machine settings as they have unsuitable values for shot weights and flow rates etc.

In this study CAE mode was used for analysis as there was no empirical data available for process or machine settings. Initial tests showed default values for injection time and other criteria were unsuitable. Analyses using various speeds and pressures were

(a) Shikaku

(b) Micro-gear

Fig. 1 The geometry of the micro-parts

Fig. 2 Project settings in the Process Wizard



Technical Paper

performed until reasonable realistic results were obtained. A filling time of 0.1seconds was used for all models, along with a VP Switch-over of 99.5% and a packing time of 3 seconds. All other process conditions were used at default values. The final pre-processing stage was to set the computational solver method and assumptions. An Enhanced-P solver was used for all analyses. In the Advanced tab, the flow solver time-step was reduced from 1 to 0.1 to provide a better resolution at the cost of processing speed. In the Criterion for Stopping Calculation section, the ‘exclude runner volume’ box was checked as micro-parts are often much smaller compared to runner volumes than macro-size parts. After all process conditions were set and checked, the analyses were run using default settings for a full run.

Post-processing The post-processing stage involves viewing and interpreting the results from the analysis. Upon completion of the calculation, the results for each model and process condition sets were checked. Each solution was checked for temperature, pressure, shear stress and shear rate and volumetric shrinkage. In the case of short shot or other errors such as hesitation, unacceptable shear stresses or over packing, the problem areas were identified and fixed before performing another analysis run. When process conditions or other settings were greatly changed, the calculation was performed in a separate Run within the same project for easy comparison between results. In this method, each model ran iterations of various conditions and settings until suitable results were obtained. Unique problems associated with micro-parts and their analyses were identified and rectified.

Many various parameters were investigated. First, the ‘Shikaku’ model will be used to illustrate some points of interest. The Shikaku model was difficult to solve as, usually, very thin parts can be difficult to manufacture by standard injection moulding techniques and care must be taken when planning the moulding conditions and gate locations. As an initial test, a standard side-gate into the part was modeled as shown in Fig. 3(a). The runner used incorporated two cold-slug wells that closely resemble those present in experimental manufacture testing. The gate was chosen to be on the edge of the part closest to the four small holes as this is the largest area of the part and provides fairly unrestricted flow from the gate. The model was initially meshed with a standard tetrahedral mesh. The first plot to be checked in the post-processing stage is always the melt-flow front. Incomplete filling (or short-shot) is one of the most common problems in injection moulding and is caused by a number of reasons as shown in Fig. 3(a). The melt-flow front distribution will display any case of incomplete filling. By comparing the flow front animation to the graph of sprue pressure vs. time, the pressure loss due to certain features can be determined as shown in Fig. 3(b). The flow progression through the cavity can be viewed by animation and critical areas such as voids and which areas fill last are easily seen. The effects on the flow of cavity features like holes or thin channels can also be checked. This is useful when rectifying short-shot problems or when redesigning model and runner geometries for optimal flow conditions. The sprue pressure graph in Fig. 3(b) shows that there is a peak in pressure loss caused by the cold slug well, followed by the large peak just after the slug well. These two losses account for a large percentage of the pressure drop and as a result, there is insufficient pressure to ensure complete filling in this case. This was caused by flow reversal from the slug well affecting the incoming flow, causing compression. Compressibility of material is not yet considered in Moldex3D yet. This shows that there is no need to accurately copy the runner shape used in manufacturing processes as this can adversely affect analysis results. A simplified runner will circumvent these errors

and provide better results. This is especially important in micro-analysis as the runner size is often much smaller and more prone to such errors. In manufacture, complex runner shapes are often difficult to produce and realistically simple geometries would be used whenever possible. The melt-flow front is also related to where weld lines appear in the cavity. Weld lines form in cavities where two flow fronts meet and change direction. Such areas often do not have smooth unidirectional flow and material properties

(a) Short shot

(b) Sprue pressure graph showing pressure losses

Fig. 3 The initial test with cold-slug gate in the runner

Fig. 4 Weld Lines form in the circled location. This area would be weaker in comparison to the rest of the part



Technical Paper

suffer in those regions.Weld-lines in functional areas such as hinges or load centres

drastically reduce the lifetime of parts and so should be confined to non-critical areas of the part whenever possible.

As can be seen in Fig. 4, the flow pattern associated with this

gate will form a weld line on the far side of the hole and will lead to weakening in this area of the part.

For micro-MIM analysis, the most important solution parameters were the plots of temperature, shear stress, shear rate and volumetric shrinkage distributions. By utilising the Results Advisor option in Moldex 9.0 as shown in Fig. 5, suggested values of each parameter were obtained as used as a base to check if solutions were accurate or not. In collusion with the Results Summary wizard, which alerts the user of problem areas in the flow, accurate solutions for each model were achieved by manipulating the settings and solving in an iterative manner.

Shear stress is one of the main sources of residual stresses in moulded parts as shown in Fig. 6. If the shear stress is not distributed evenly it can cause dimensional problems during and after the filling stage. If the shear stress is too high, stress-induced problems may also occur in the part, such as flow hesitation and burning out of the material. According to the results advisor in Moldex, the shear stress should be controlled to be less than 1MPa for most analyses.

Shear rate is the rate of shear deformation of the material during flow, as shown in Fig. 7. A higher rate of shear indicates a higher rate of deformation, that is, the molecule chains in the polymer were deformed rapidly and had no chance to relax or recoil. Shear rate is related to the velocity gradient of the flow and the molecular orientation of the material. If the shear rate is too high, molecular chains can be broken and the strength of the product will be decreased. Viscous heating of the material through shear will also be present. From the Results Advisor, the recommended value for this shear rate usually falls below 10000 1/second, but for micro-parts this value is difficult to obtain in most cases. Moldex 9.0 performs best under standard machine settings for most values, such as filling time, which has a minimum filling time of approximately 0.05 seconds. If using a default machine filling time for a micro-cavity, the filling time would be in the order of 0.0005 seconds which causes very high velocities in the cavity leading to a number of errors such as high shear stress and shear rates. In CAE settings, users are able to enter more realistic values for filling time. In general, in all observed micro-MIM analyses shear rate was higher than that usually observed in standard macro-size cavities. In this study a shear rate value much higher than 50000 1/second was assumed to be undesirable. This value was derived from average shear rates in micro-cavities that had no warning errors from the Results Summary Wizards and had good, balanced flow profiles. Values for max shear rate will vary with material properties but in general, high shear rate leads to burning out of the material, pressure losses and hesitation in thin walled parts and should be reduced whenever possible.

The temperature distribution helps to show the effects of heat transfer throughout the part and is of great use when designing cooling channels, specifying cooling temperatures and times, and identifying areas of viscous heating from shear, or flow freezing leading to hesitation as shown in Fig. 8. In this study, no cooling was specified but could be easily designed from the temperature distribution if required at a later date. The main use of the temperature distribution was to identify areas inside the cavity where calculation was prematurely stopped. In most standard analyses, the filling calculation is stopped when approximately 99% of the cavity is filled. This is in order to prevent the sharp pressure increase present during the final 1% from adversely affecting the simulation. As the size of a micro-part cavity is very small compared to the runner, this final percentage is often a substantial part of the cavity and solver settings must be changed to reflect this or an area in the cavity will appear where the results cannot be read. When setting the computation parameters, the “Exclude runner volume”

Fig. 5 The result summary window from Moldex 9.0

Fig. 6 Shear stress during filling. The areas on the sides of the hole show very high stresses which would lead to problems

Fig. 7 Shear rate during filling. The areas on the sides would be subject to high viscous heating amongst other problems



Technical Paper

box should be ticked in the “Criterion for Stopping Calculation” area in the advanced settings tab. When viewing the temperature distribution, the areas of ‘no calculation’ are easily seen. These areas appear due to many complex reasons, such as poor resolution, time-step being too large and due to a solver error in Moldex 9.0, resolved in Moldex 9.1.

The volumetric shrinkage at ‘end of packing stage (EoP)’ is also important for all injection moulding analyses as shown in Fig. 9. If the distribution of shrinkage is imbalanced inside the cavity it is likely the part will warp and lose functionality after ejection from the cavity. Also, the degree of shrinkage is important. An often-used value for reasonable shrinkage is 4%. If the shrinkage exceeds 4% by a large amount shrinkage of the part occurs to a great degree and the post-ejection shape cannot be controlled with any accuracy. The volumetric shrinkage is dependant upon the thickness of the part, the temperature of the material and the cooling rate and distribution inside the mould. In the case of the test parts in this study, no cooling channels were present so only the balance was analysed.

Results and DiscussionsDetermining micro-analysis process conditions Firstly, an ideal set of process conditions for micro-size cavities in Moldex 9.0 was investigated. The model of the Shikaku test part was used for the investigation. After performing analyses on the basic Shikaku cavity many areas with poor flow properties were identified due to the presence of the large hole in the centre of the part. There were no ideal gate locations that would alleviate the problems. An alternative geometry for Shikaku was modelled as shown in Fig. 10. In this model, the central hole was filled in and used as a location to place the gate. The thickness of this region was also increased so as to provide a more ideal flow pattern from the gate. With this geometry, the manufacturer would have to cut the ‘filled in’ section from the part after manufacture which would lead to further costs.

A series of tests were performed on the new model with varying filling times, flow rates, injection pressures and packing pressures until error-free accurate results were obtained. The testing parameters are shown in Table 1. The flow rate was set at a percentage of maximum possible. The injection pressure and packing pressure were set at a percentage of maximum pressure, which was set at 300MPa in CAE Mode.

Run 1Run 1 was performed at standard default settings in CAE mode. The filling time was much faster than that of standard analyses. As can be seen in Fig. 11, the new geometry has a more balanced flow profile and no weld-lines in critical locations, but the shear rate was still unsuitable, with a max value exceeding 500,000/s. The shear stress also greatly exceeded acceptable limits.

Run 2The results showed that although the shear stress was now within acceptable values, the shear rate was still too high as shown in Fig.

Run No. Filling time(s)

Flow rate(% of max)

Inj. Pres.(%)

Pack Pres.(%)

Shear RateOK

Shear StressOK

1 0.00242 50 70 70 No No2 0.05 20 40 50 No Yes3a 0.5 20 40 50 Yes* No4 0.1 50 70 70 Yes Yes5b 0.1 50 70 70 No Yes

Table 1 Testing parameters

Fig. 8 Temperature distribution. The region in the circle is the area of no calculation

Fig. 9 Volumetric Shrinkage at EoP. The imbalance leads to warpage of the part

Fig. 10 The alternative geometry of the part, gate location and runner

a) In Run 3, short shot occurred therefore all process settings were deemed unsuitable despite falling within acceptable ranges for some parameters. b) In Run 5, a simplified geometry for the cavity was used.



Technical Paper

12. The shear rate is much improved but still high with critical areas having values between 20000 to 50,000/s. Further improvement was investigated as shown in Fig. 13.

Run 3The shear rate now fell within acceptable limits but the shear

stresses were too high. The flow rate at this speed was too slow to completely fill the model before hesitation and short-shot occurred as shown in Fig. 14.

Run 4 With these settings the shear rate and shear stresses both fell within acceptable ranges as shown in Fig. 15.

The volume shrinkage distribution of the alternative shape was also investigated once the process conditions were satisfactory. The volume shrinkage is shown in Fig. 16, and it can be seen that it is much more balanced and less likely to have a large degree of warpage.

In this model, the thin parts of the model shape are those subjected to the highest shear stress and are the restricting factor of this geometry. There is also a degree of sudden expansion occurring from the flow from thin regions to the thicker regions. This could be improved by rounding corners and/or increasing the taper between the surfaces.

The thickening of the region where the gate was located was designed in order to prevent shear problems due to sudden expansion and friction. The distribution of shear rate near the gate is shown in Fig. 17.

Run 5 A final analysis was run using a model with no central hole as shown in Fig. 18. This geometry would be less desirable for manufacture

Fig. 11 The Melt Flow Front and the distribution. The shear rate is still in the order of 10 times the recommended level

(a) Melt Flow Front

(b) Shear Rate

Fig. 12 The Shear Stress distribution. All values of shear stress fall under 0.6 MPa

Fig. 13 The Shear Rate distribution. Values range between 20000-50000/s

Fig. 14 The melt flow front. Incomplete filling can be seen indicating short-shot



as it would require a minimum of two further processes to achieve the final product shape; cutting of the central hole, and pressing of the area surrounding the hole to the specified thickness.

The results show that this model has the most balanced melt flow front and volumetric shrinkage, as seen in Fig. 19.

An interesting thing to note was this geometry also had an unsuitable shear rate when using the previously determined process conditions. The shear rate near the gate was very high due to the perpendicular flow from the gate, causing high friction. The cross-section of the shear rate at the gate is shown in Fig. 20.

In order to resolve the shear rate, the input velocity must be decreased, but care must be taken not to cause a short-shot as in the case of Run 3. In general, gating perpendicularly into thin regions should be avoided when possible. The best set of process conditions for this model came from Run 4. The filling time was found to have more effect on the results than the other settings. Moldex 9.0 does not handle very fast filling times well. Depending on the size of the cavity, filling times should be kept within 0.5-0.05 seconds when possible. Shorter filling times result in shear problems, and longer times can result in short shot due to the rapid cooling of flow due to heat transfer, which is much more significant in micro-analyses.

Improving accuracy of micro-analysis Using the process conditions derived previously, tests were run on

the micro-gear cavity shown in Fig. 21 in order to reduce errors and anomalies in micro-analyses and to improve accuracy. Varied geometrical models with different runner/gate locations shown in Fig. 22 were analysed.

The models were initially meshed with a standard tetrahedral mesh. The material used in this study came from empirical data of material properties of Taisei Kogyo’s MIM material, SUS316L 65:35 [1]. The process conditions from Shikaku Run 4 were checked

Fig. 15 The Shear Stress and Shear Rate distributions. The critical areas of the part now have a value of approximately 0.4MPa and 7000-30000/s respectively.

(a) Shear Stress

(b) Shear Rate

Fig. 16 The volume shrinkage distribution of the alternative geometry

Fig. 17 Shear Rate Distribution of Run 4, showing the cross-section near the gate and the relatively low shear rate

Fig. 18 Model with no central hole

Technical Paper



for suitability for this cavity and tested prior to the investigation. In all analyses of the models, areas of no calculation could be seen spread throughout the cavity (Fig. 23), as in the case of the area of last fill in Shikaku, seen on the temperature distribution (Fig. 8). A detailed description of all results can be found in the detailed Micro-Gear report [2]. As the cubic capacity of the micro-gear is much smaller than that of the Shikaku model, more care must be

taken with accuracy or small assumption errors can greatly affect the outcome. For the Shikaku analysis, the area of no calculation was not in a critical region and had negligible affect on the outcome. In the micro-gear analysis, the same problems had a large affect and affected the shear stress distribution as shown in Fig. 23.

A variety of solutions were applied to attempt to remove this inaccuracy. Initially, the problem was thought to stem from an imbalance in the flow profile of the models tested. A final runner/gate model was created and tested. In this case a ‘cap’ was created on the top surface of the gear and the gate was located onto the cap as shown in Fig. 24. This enabled it so the entire top surface of the gear to act as a gate and flow could be more symmetrical. The entire cap and gate location would have to be removed after manufacture by a cutting method as shown in Fig. 25. It is shown in Fig. 26 that the runner cap model provides a much more symmetrical flow front and resulting post-processing material conditions.

Despite being symmetrical and having a smooth flow profile, the no calculation error was still present (Fig. 27) and greatly affected the results. Many causes for these errors were investigated and the results are explained below. Firstly, a common cause of such areas is due to the solver resolution being too low. If the time-step of the computational solver is too large, there will be too few solver iterations for the results to show small changes. To increase the resolution, the time-step must be decreased, which enables the computation to solve at a greater number of times per second. In the

Fig. 19 Melt Front Flow Time and Volumetric shrinkage at End of Packing phase

(a) Melt Front Flow Time

(b) Volumetric shrinkage

Fig. 20 Shear rate distribution at the gate location

Fig. 21 Geometry of the micro-gear part

(c) Model 2R2G (d) Model 3R3G

(a) Model 1R2G (b) Model 1R4G

Fig. 22 Geometry of the runner/gate locations

Technical Paper



advanced settings window of the computational parameter window, the default solver time-step is set to a value of 1. Various time steps were tested ranging from 0.02 to 1. By decreasing the solver time step however, the analysis time is greatly increased. A balance must be found for efficient time and resource usage. Initially with the default time step of 1, the analysis took approximately 10 hours on the computer used. At the lower end, with a time step of 0.02, the analysis took over 3 days to complete. Whilst the resolution had

improved and area regions decreased such a level is rarely required. A time step of 0.1 was tested and this provided better resolution without sacrificing too much time, the analysis took about 20 hours to complete.

The results were more accurate but the problem errors were still present. The temperature distribution was used to display the areas of no calculation clearly (Fig. 28). Secondly, the effect of

Fig. 23 The shear stress distributions for the micro-gear tests. Many small areas of no calculation are present

(b) Model 1R4G

(a) Model 1R2G

Fig. 24 The runner cap shape and location

Fig. 25 A cross-sectional view of the runner cap model and mesh elements. The cap area above the red line must be removed after manufacture. The internal tetra mesh elements can be seen

Fig. 26 The volumetric shrinkage distribution for the capped model. The shrinkage is symmetrical and more balanced than previous models

Fig. 27 The shear stress distribution for the runner-cap model with BLM in Moldex 9.0

Technical Paper



the standard tetra mesh elements beginning to become inaccurate for micro-CFD models was investigated. In injection moulding analysis, the element layer count across the part thickness direction is very important. This is because the element layer count determines the resolution of the analysis result. For example, in the case of the temperature distribution shown in Fig. 28, the temperature changes rapidly on the part’s surface due to a combination of shear heating and contact with the mould causing heat transfer. With low resolution, such changes cannot be seen and inaccuracy

develops. When creating standard tetra meshes, the element count across the part cannot be controlled by the user, thus the analysis cannot provide correct temperature distribution in poor quality mesh regions. However, accurate results can be achieved by using a different meshing method. For complex flow profiles or unusual material properties, a hybrid mesh often provides the best results although hybrid meshes can be very difficult and time-consuming to create. A better solution is to use a Boundary Layer Mesh, which is a simplified hybrid mesh which can be created automatically in Rhino 4.0. A boundary layer mesh, or BLM, consists of the standard tetra mesh with a thin layer of prism mesh on the outer surface as shown in Fig. 29. BLM meshes increase the element layer count and therefore the resolution which, in the case of micro-injection moulding analysis, is doubly important. The shear heating phenomena can be simulated more accurately. Further, the analysis

Fig. 28 The temperature distribution for the runner cap model using tetra mesh in Moldex 9.0

Fig. 29 Showing the cross-section of the BLM mesh. Two very thin prism elements can be seen outside the tetra elements

Fig. 30 The temperature distribution for the runner cap model using BLM mesh in Moldex 9.0

Fig. 31 The warning message W1502 in the packing log file in Moldex 9.0

Fig. 32 The temperature distribution for the runner cap model using BLM mesh in Moldex 9.1

Technical Paper



results of the filling pattern, pressure profile and so on, can be predicted more accurately as well.

An analysis of the part using the original process conditions and a BLM mesh was performed and the temperature distribution was checked for anomalous areas. The result is shown in Fig. 30.

The problem still persists for a BLM mesh in Moldex 9.0. All the parameters and settings were checked and a warning message W1502 located in the packing log file was investigated as shown in Fig. 31.

The cause for this warning is not known but in order to test if it had an effect on the result, one analysis was performed in the new Moldex 9.1, in which many small bugs have been fixed. The warning message was not present in the log file for the Moldex 9.1 analysis and the temperature distribution is shown in Fig. 32.

As can be seen, the distribution is smooth and there are no problem areas such as in Fig. 30. The resolution of this model is good and is still reasonably fast and easy to create. It is recommended that Moldex 9.1 should be used if problem areas persist, and all micro-size analyses performed in Moldex should use a BLM mesh where possible for improved accuracy.

ConclusionsTwo micro-size MIM test parts were analysed using Moldex 9.0 and Rhino 4.0. A series of suitable process conditions were devised for use in micro-analyses in Moldex 9.0. Common errors present in micro-analyses were identified and solutions were investigated.

(1) Filling time has a large effect when performing micro-analyses. Moldex 9.0 works best with filling times in the range of 0.05-0.5 seconds.

(2) Extra care must be taken with runner shapes and gate locations in micro-analysis due to the exceptionally small and thin cavity shapes.

(3) Areas of no calculation are common in micro-cavities and present a substantial inaccuracy. These errors can be reduced by using a BLM with reduced time-step and preferably, Moldex 9.1.

AcknowledgmentsThe authors of this paper would like to thank Mr. Hisahiro Tanaka of Saeilo Japan Inc., Osaka, for providing his assistance with analysis methods and advice for both Moldex 3D and Rhino programs

References[1] Julin Chiao, Polymer Property Analysis Report, MIM SUS316L 65:35. Serial No. 00362, Supplier – Core Tech, Material Code – TAISEI-1024, CAE Laboratory, Department of Chemical Engineering, National Tsing-Hua University, 19 Dec. 2002.[2] Ian Andrews, Taisei Kogyo Report 2 – Micro-MIM gear Analysis, Osaka Prefectural Technical College, January 2009.

Technical Paper

Publishing technical papers in PIM International

Publisher & editorial officesInovar Communications Ltd 2 The Rural Enterprise Centre, Battlefield Enterprise Park, Shrewsbury SY1 3FE, United KingdomT: +44 (0)1743 454990F: +44 (0)1743 469909E: [email protected]


Since its launch in March 2007 Powder Injection Moulding International has firmly established itself as the leading publication for the international metal, ceramic and carbide injection moulding community.

We believe that our unique combination of business news, market studies and quality technical papers provides an ideal balance for an industry that still thrives on innovative technological developments and the application of the latest research.

We welcome the submission of technical papers from the research community and industry alike. If you would like to publish with us, please contact Nick Williams on +44 (0)1743 454991 or email [email protected].


Powder Injection Moulding International March 201066 Vol. 4 No. 1www.pim-international.com












Company visits

Technical papers




•

•

•

•

•

Inovar Communications Ltd Tel: +44 (0)1743 454990

2 The Rural Enterprise Centre, Battlefield Enterprise Park Fax: +44 (0)1743 469909

Shrewsbury SY1 3FE, United Kingdom [email protected]

Full page PIM March 2009.indd 1 3/4/2010 3:45:11 PMMarch 2010 Technical Papers.indd66 66 3/5/2010 1:24:38 PM


Influence of Particle Size Distribution and Chemical Composition of the Powder on Final Properties of Inconel 718 Fabricated by Metal Injection Moulding (MIM)

Inconel 718 is one of the most common Ni-base superalloys due to its large number of engineering applications in automotive, chemical, aerospace and energy generation industries. The aim of this work is to study the influence of the particle size distribution along with the chemical composition of different Inconel 718 powders on the final properties of components fabricated by Metal Injection Moulding (MIM). In order to carry out this study, five feedstocks have been prepared with monomodal, bimodal, narrow and wide particle size distributions mixing four raw Inconel 718 powders in different proportions. Next, all of the feedstocks are injection moulded to fabricate green parts that are subjected to debinding and sintering processes using different atmospheres and temperature cycles. Finally, the relative density, porosity and hardness of the sintered materials are determined relating the particle size and chemical characteristics of the powder with the results. There are not too many papers that provide information about MIM of Inconel, making this technology highly suitable for reducing production costs in many applications. This article sheds light on what are the most convenient Inconel 718 powders to be processed by MIM.

J.M. Contreras1*, A. Jiménez-Morales2 and J.M. Torralba3

1,2Dept. of Materials Science and Engineering,3IMDEA Materials,Universidad Carlos III de Madrid , Avda. de la Universidad 30, 28911, Leganés (Madrid), Spain*Corresponding author. E-mail address: [email protected] (J. M. Contreras)

IntroductionMetal injection moulding represents an alternative process to manufacture powder metallurgy components. It is inspired by the polymer injection process allowing the fabrication of small, complex, near-net-shaped parts in a profitable way. This technology has been successfully applied in the last two decades to a great number of ceramic and metallic engineering materials, growing in numbers every year. Among all of them, nickel base superalloys seem to be good candidates to be processed by this technique, allowing cost savings when compared to other techniques such as investment casting. Inconel 718 is the superalloy most extensively used in the industry for applications that require high temperatures. This material can be hardened by precipitation of different phases containing Nb, Al and Ti and it combines high strength with a good corrosion resistance. Many applications of Inconel 718 are found in aerospace, energy generation, chemical, medical and tooling

industries [1]. One important disadvantage is the careful analysis and control of the processing of this material, since different elements such as carbon, oxygen and nitrogen cause a deterioration of its mechanical properties [2].

The aim of this work is to investigate the influence of different powder characteristics, such as the particle size distribution and the chemical phases present in the raw powder, on the processing of the superalloy Inconel 718 by MIM.

ExperimentalThe four Inconel 718 powders that are used in this work (named Inco 1, Inco 2, Inco 3 and Inco 4) were fabricated by gas atomisation in different atomisation batches. Some of the characteristics of these powders such as the particle size distribution, pycnometer, apparent and tap densities are presented in Table 1. For all the powders, both the production method (gas atomisation) and the morphology (spherical) are very similar but the particle size distribution noticeably varies from Inco 1 to Inco 4.

Fig. 1 presents the micrographs of the four Inconel powders. As it is observed in Fig. 2 the powder Inco 3, possibly due to a wrong atomisation process, shows irregular particles that differ from the morphology observed in the rest of the powders. Fig. 3 gives the particle size distribution of the four different Inconel powders.

The chemical composition of the raw Inconel powders is presented in Table 2. The four powders are mixed with a Turbula mixer during 30 minutes in the proportions that are shown in Table 3 to fabricate powder blends with different particle size distributions. Thus, powder blends 1 and 3 present monomodal size distributions, blends 2 and 4 show bimodal size distributions and blend 5 has a very wide particle size distribution.

Table 1. The characteristics of the four Inconel 718 powders that are used in this work: pycnometer density, apparent density, tap density and particle size distribution

Inco 1 Inco 2 Inco 3 Inco 4

Density g/cm3

Pycnometer 8.16 8.10 8.08 8.09

Apparent 2.96 4.19 3.49 4.36

Tap 4.05 5.15 4.34 5.03

Size distribution

d10: 3.6 18,0 57.3 68.5

d50: 11.1 25.3 75.6 93.4

d90: 22.8 34.9 102.9 156.7

Sw 3.2 8.9 10.1 7.1

Technical Paper

Originally presented at Euro PM2009, Copenhagen, Germany. Re-printed with kind permission of European Powder Metallurgy Association, Shrewsbury, UK













Company visits

Technical papers




•

•

•

•

•

Inovar Communications Ltd Tel: +44 (0)1743 454990

2 The Rural Enterprise Centre, Battlefield Enterprise Park Fax: +44 (0)1743 469909

Shrewsbury SY1 3FE, United Kingdom [email protected]

Full page PIM March 2009.indd 1 3/4/2010 3:45:11 PM March 2010 Technical Papers.indd67 67 3/5/2010 1:24:42 PM


Technical Paper

The five powder blends are mixed with an internal mixer (Haake Rheocord 252P) for the fabrication of powder-binder blends with different solids loadings in the interval from 60% to 78% by volume, depending on the powder mixture that is used and the ease for obtaining a homogeneous blend with the polymeric binder. The composition of the binder system is 40% high density polyethylene, 55% paraffin wax and 5% stearic acid. The mixing process is carried out at a temperature of 170ºC for thirty minutes. This amount of time has been observed to result in total homogeneity of all of the powder-binder mixtures. The torque evolution during the mixing process is used to evaluate the critical and optimal solids loading of each powder-binder mixture (Table 4).

Taking the optimal powder contents, five Inconel feedstocks (1 to 5) are fabricated in a ThermoHAAKE twin screw extruder at 170ºC and then injection moulded at this temperature to fabricate green specimens (length 62.7 mm x width 12 mm x thickness 3 mm). The debinding is carried out in two steps: first, green components are solvent debinded in hexane at 60ºC for 240 minutes to remove the paraffin wax and the stearic acid. Then, thermal debinding is driven in different atmospheres (air, vacuum and argon) to remove the remaining binder, obtaining brown parts from all of the feedstocks that are free of defects. In the last stage,

C Mn Si S Cr Ni Mo Al Ti Co B Cu Fe Nb N O

Inco 1 0,045 0,01 0,13 0,001 17,0 51,5 3,00 0,64 1,00 - 0,003 0,01 22,00 5,10 0,002 0,054

Inco 2 0,052 0,10 0,32 0,008 18,4 53,4 3,06 0,40 0,82 0,02 - 0,05 18,10 4,94 0,008 0,025

Inco 3 0,046 0,14 0,10 0,004 18,8 53,5 3,03 0,57 1,04 0,26 0,005 0,02 17,46 5,02 0,002 0,014

Inco 4 0,029 0,05 0,08 - 18,1 50,2 3,20 0,39 0,93 - 0,002 0,06 21,65 5,30 0,002 0,010

FEEDSTOCK 1 2 3 4 5

Critical solids loading (vol.%)

65-68 68-70 70-73 75-78 78-80

Optimal solids loading (vol.%)

63 65 68 73 75

Table 2 Chemical composition of Inconel 718 powders

Table 3 The proportions (% by volume) of the Inconel 718 powders that are used to fabricate the powder blends 1 to 5

Table 4 The critical and optimal solids loading of the Inconel feedstocks that are determined by torque rheometry

Fig. 1 SEM images of the Inconel powders: (a) Inco 1 (<22 m), b) Inco 2 (16-45 m), c) Inco 3 (45-63 m) and d) Inco 4 (95-212 m)

Fig. 2 SEM image of Inco 3 under higher magnification Fig. 3 Particle size distribution of the four Inconel powders (Inco 1 to Inco 4) that are used in this work

Blend 1 2 3 4 5

Inco 1 0 0 100 50 25

Inco 2 100 50 0 0 25

Inco 3 0 0 0 50 25

Inco 4 0 50 0 0 25

components are sintered in a tubular high vacuum furnace (2 x 10-5 mbar). Finally, the sintered components are characterised through measurements of the density, the shrinkage and the hardness (Vickers 30).



Results and DiscussionTable 4 shows the influence of the particle size distribution on the critical solids loading of the powder-binder mixtures 1 to 5. Bimodal distributions 2 and 4 present higher critical solids loading than monomodal distributions 1 and 3. Mixture 5, which has the widest particle size distribution, presents the best packing capacity and therefore, the highest critical solids loading. This implies that to attain a high solids loading in the mixture, mixture 5 is the best choice in comparison to the monomodal and the bimodal distributions. These results are in concordance with those obtained by Agote et al. [3], who has studied porcelain feedstocks where the critical solids loading is strongly influenced by the powder granulometry. The critical powder volume content (CPVC) is inversely proportional to the powder particle size; thus, it decreases when the powder particle size becomes larger. At the same time, the critical solids loading is also dependent on the particle size distribution. Thus, the broader the particle size distribution, the higher the critical solids loading [4].

The carbon, oxygen and nitrogen contents that exist in the superalloy Inconel 718 are very important because these elements are of detriment to the mechanical properties [5]. For this reason, it is very important to select the more convenient conditions during thermal treatments that lead to the lowest levels of these elements. The different debinding cycles that have been used in this study are presented in Table 5. As it is observed, the utilisation of three types of atmosphere are compared and Fig. 4 shows the carbon and oxygen contents after thermal debinding. The thermal cycle DBA-1 conducted in air leads to low carbon contents but a high degree of oxidation whereas the cycles DBV-1 to DBV-3 present more difficulties to remove the binder but, at the same time, they are more protective. The use of vacuum during debinding means very long thermal cycles are required to remove the binder, thus causing a progressive increase of the oxygen absorption. Argon gas (cycle DBR-1) seems to be the most convenient atmosphere allowing good elimination of the binder together with low oxidation levels. Thus, cycle DBR-1 is selected to fabricate brown parts of Inconel 718.

Sintering of the materials is performed using the conditions that are summarised in Table 6. All the cycles are conducted in vacuum in the temperature range from 1270ºC to 1300ºC. The carbon,

oxygen and nitrogen levels after sintering are very close to those shown previously in Fig. 4. Fig. 5 presents the relative density and the shrinkage of the Inconel components sintered using the cycles STR-1 to STR-4. Relative densities are in the range from 94% to 98% with cycle STR.3 (1280ºC – 360 minutes) the one that leads to the highest densities. It is worth mentioning that the particle size distribution does not seem to influence the sintering behaviour of the material. In spite of that, the materials 1 and 2, and to a lesser extent the material 5, are present in all cases at lower densities than materials 3 and 4. The reason of the poor sintering observed in these materials is the existence of Laves phase in the Inconel powder Inco2, which could not be found in the rest of the raw powders.

Fig. 6 shows the TGA-DTA analysis of the Inconel 718 powder Inco2, in which the existence of a small endothermic peak at approximately 1180ºC can be observed that, according to the literature [6], corresponds to the melting of the Laves phase. This phase appears surrounding the particles of the powder during the cooling of this alloy from a high temperature and it is damaging for the sintering since it inhibits the process [7]. In addition, this phase can also produce the phenomenon of incipient melting during heating due to a lower melting point than the rest of the material leading to porosity in the sintered material [8].

Coming back to Fig. 5, it is observed that the shrinkage undergone by the materials during the sintering process is noticeably influenced by the solids loading with which the feedstock has been fabricated. In this way, parts with a higher powder content present a lower shrinkage and, thus, a better dimensional control can be done. These results mark the importance of the particle size distribution on the shrinkage and dimensional accuracy of the final product. As can be observed, monomodal size distributions (materials 1 and 3) lead to a lower solids loading and a higher shrinkage than bimodal size distributions (2 and 4). In comparison, the use of a very wide particle size distribution (material 5) allows the use of the highest powder content to fabricate feedstocks, which is advantageous for the dimensional control of the sintered parts.

An approach to the mechanical properties of the sintered components is evaluated through measurements of hardness, Vickers 30 (HV30). The results obtained are presented in Fig. 7, where it is observed that hardness follows the same trend as the

CYCLE AtmosphereT1 (ºC)/

V1 (ºC/min)Plateau 1

(min)T2 (ºC)/

V2 (ºC/min)Plateau 2

(min)T3 (ºC) /

V3 (ºC/min) Plateau 3

(min)T4 (ºC) /

V4 (ºC/min)Time (min)

DBA-1 Air 200 / 5 30 350 / 4 60 500 / 4 60 25 / 10 331

DBV-1 Vacuum - - 350 / 2,0 60 500 / 4,0 60 - 320

DBV-2 Vacuum - - 350 / 1,0 90 500 / 1,0 90 - 655

DBV-3 Vacuum - - 350 / 0,5 120 500 / 0,5 120 - 1290

DBR-1 Argon 200 / 2 30 350 / 2 60 500 / 3 120 25 / 10 487

Table 5 The thermal debinding cycles to remove the binder system from the green parts

Fig. 4 Carbon and oxygen contents after thermal debinding using different atmospheres

Technical Paper



To subscribe to Powder Injection Moulding International today please return this form by fax to: +44 (0)1743 469909 or subscribe on-line at www.pim-international.com

Subscription to Powder Injection Moulding International for one year (4 issues) = £95

Subscription for one year + all back issues (since March 2007) *special offer* = £350

Your contact details

Title ........................ Forename(s) ..........................................................Family Name .....................................................................

Job Title/Position .................................................................................................................................................................................

Organisation .........................................................................................................................................................................................

Full address ..........................................................................................................................................................................................

.................................................................................................................................................................................................................

Postcode....................................................................................Country ...........................................................................................

Tel: .............................................................................................Fax: ...................................................................................................

E-mail: ........................................................................................

Subscription periodPowder Injection Moulding International is published on a quarterly basis. Your subscription will commence with the next available issue unless otherwise requested (please email [email protected])

Multiple subscription discount *save 25%*Organisations wishing to purchase four or more subscriptions to Powder Injection Moulding International can receive 25% discount on the total cost. Please contact Paul Whittaker, email: [email protected], to order. Payment options

Please invoice me. I understand that subscriptions will not start until full payment is made.

Please charge £.............. to my credit card as follows: VISA MasterCard American Express

Name on Card: .................................................................................................................................................

Card Number: .......................................................................................... 3/4 Digit Security Code ...........

Expiry Date: ..............................................................................................

Signature: ................................................................................................... Date: ..............................................


Or mail to: Inovar Communications Limited, 2 The Rural Enterprise Centre, Battlefield Enterprise Park, Shrewsbury SY1 3FE, United KingdomEmail: [email protected] Tel: +44 (0)1743 454990

Fax to: +44 (0) 1743 469 909

MARPIMI10

Subscribe today for only £95 and stay up-to-date with PIM industry developments

order online at


Technical Paper

density. It seems that the Laves phase determines, in the same way, the mechanical properties of the sintered materials. These values are in accordance with the value of 414 HV30 found by Thomas et al. [9] for Inconel 718 subjected to a hardening thermal treatment at 800ºC for 3 hours.

ConclusionsThe results obtained in this work indicate that the particle size distribution of the Inconel powder present an important influence on the optimal solids loading to produce feedstock. The bimodal particle size distributions lead to a better packing than monomodal ones, allowing an increase in the powder content during feedstock fabrication. On the other hand, powders with a very wide particle size distribution are better to attain high solids loadings in comparison with monomodal and bimodal size distributions. It is worth mentioning that increasing the solids loading allows for a reduction in the shrinkage and improved dimensional accuracy of the final product. On the contrary, the particle size distribution of the Inconel powders does not seem to affect the sintering of the material, it being more influenced by the existence of phases in the raw powder such as the Laves phase, that acts to inhibit the process.

AcknowledgementsThe authors wish to thank the Spanish Government and especially the Education and Science Ministry for the concession of the FPU grant. In addition, the authors wish to thank both the program ESTRUMAT-CM (reference MAT/77) from the Comunidad de Madrid, which has funded this research work, and the Industrial Materials Institute (IMI) of the National Research Council of Canada (CNRC) in Montreal (Canada) for allowing us to use their facilities.

References[1] P.A. Davies, G.R. Dunstan. Metal Powder report, pp. 14-19, 2004.[2] G. Appa Rao, M. Srinivas. Mat. Sci. and Eng., vol. A 435-436, pp. 84-99, 2006.[3] I. Agote, A. Odriozola. J. of the European Cer. Soc., vol. 21, pp. 2843-2853, 2001

DEBINDING CYCLE

SINTERING CYCLE

Atmosphere TO (ºC)T1 (ºC) / V1 (ºC/min)

Plateau 1 (min)

T2 (ºC) / V2 (ºC/min)

time (min)

DBR-1 STR-1 Vacuum 25 1270 / 5 120 25 / 5 618

DBR-1 STR-2 Vacuum 25 1280 / 5 120 25 / 5 622

DBR-1 STR-3 Vacuum 25 1280 / 5 360 25 / 5 862

DBR-1 STR-4 Vacuum 25 1300 / 5 120 25 / 5 630

Table 6. The sintering cycles: atmospheres, thermal cycle and duration.

[4] T. Honek, B. Hausnerova, P. Saha. Polymer Composites, pp. 30-36, 2005.[5] A. Thom. Proceedings of the EuroPM2004, pp. 493-496, 2004.[6] A. Strondl, R. Fischer. Material Science and Engineering A, vol. 480, pp. 138-147, 2008.[7] K.F. Hens. Adv. in Powder Met. and Particulate Mat., vol. 4, pp.137-149, 1994.[8] G.H.K. Bouse. Superalloy 718-Metallurgy and Applications, pp. 69-77, 1989.[9] A. Thomas, M. El-Wahabi. J. of Mat. Process. Tech., vol. 177, pp. 469-472, 2006.

Fig. 6 TGA-DTA analysis of Inconel 718 powder Inco2

Fig. 7 Hardness of Inconel parts sintered at 1280ºC for 360 minutes (cycle STR-3)

Fig. 5 Relative density and shrinkage of Inconel components after sintering in a vacuum



To subscribe to Powder Injection Moulding International today please return this form by fax to: +44 (0)1743 469909 or subscribe on-line at www.pim-international.com

Subscription to Powder Injection Moulding International for one year (4 issues) = £95

Subscription for one year + all back issues (since March 2007) *special offer* = £350

Your contact details

Title ........................ Forename(s) ..........................................................Family Name .....................................................................

Job Title/Position .................................................................................................................................................................................

Organisation .........................................................................................................................................................................................

Full address ..........................................................................................................................................................................................

.................................................................................................................................................................................................................

Postcode....................................................................................Country ...........................................................................................

Tel: .............................................................................................Fax: ...................................................................................................

E-mail: ........................................................................................

Subscription periodPowder Injection Moulding International is published on a quarterly basis. Your subscription will commence with the next available issue unless otherwise requested (please email [email protected])

Multiple subscription discount *save 25%*Organisations wishing to purchase four or more subscriptions to Powder Injection Moulding International can receive 25% discount on the total cost. Please contact Paul Whittaker, email: [email protected], to order. Payment options

Please invoice me. I understand that subscriptions will not start until full payment is made.

Please charge £.............. to my credit card as follows: VISA MasterCard American Express

Name on Card: .................................................................................................................................................

Card Number: .......................................................................................... 3/4 Digit Security Code ...........

Expiry Date: ..............................................................................................

Signature: ................................................................................................... Date: ..............................................


Or mail to: Inovar Communications Limited, 2 The Rural Enterprise Centre, Battlefield Enterprise Park, Shrewsbury SY1 3FE, United KingdomEmail: [email protected] Tel: +44 (0)1743 454990

Fax to: +44 (0) 1743 469 909

MARPIMI10

Subscribe today for only £95 and stay up-to-date with PIM industry developments

order online at




Events Guide Advertisers’ Index2010

Atomisation for Metal Powders March 25-26, Manchester, UK www.perdac.com/5

MIM2010 Conference on the Injection Moulding of Metals, Ceramics and Carbides March 29-31, Long Beach, California, USA www.mpif.org

2010 SAE World Congress April 12-15, Detroit, USA www.sae.org

4th International Conference Magnetism and Metallurgy WMM‘10 June 9 - 11, Freiberg, Germany PowderMet 2010 - MPIF/APMI International Conference on Powder Metallurgy & Particulate Materials June 27-30, Hollywood (Ft. Lauderdale), FL, USA www.mpif.org

Titanium 2010 October 3-6, Orlando, Florida www.titanium.org 2010 Powder Metallurgy World Congress & Exhibition October 10-14, Florence, Italy www.epma.com/pm2010 55th Annual Conference on Magnetism and Magnetic Materials, MMM November 14–18, Atlanta, Georgia, USA, www.magnetism.org

For the latest events please visit www.pim-international.com

Your route to the global PIM community!

Powder Injection Moulding International Powder Injection Moulding International provides an advertising platform for any company involved in the powder injection moulding sector to demonstrate its expertise to the market.

To discuss advertising opportunities please contact:Jon Craxford, Advertising Sales Manager Tel: +44 (0) 207 1939 749Email: [email protected].


Advanced Materials Technologies Pte Ltd 6

Advanced Metalworking Practices LLC 18

Arburg GmbH & Co. KG Outside back cover

atect corporation 8

BASF SE 4

BMV Burkard Metallpulververtrieb GmbH 13

Centorr Vacuum Industries, Inc. 9

Cremer Thermoprozessanlagen GmbH Inside front cover

Dynamic Group 19

Elnik Systems 12

eMBe Products & Services GmbH 17

EPMA PM2010 42

Erowa AG 17

Eurotungstene Metal Powders 2

International PM Directory 28

Kerafol GmbH 14

Lömi GmbH 5

MPIF (MIM2010) 20

MPIF (PowderMet 2010) Inside back cover

Parmaco Metal Injection Molding AG 10

Polymer-Chemie GmbH 7

Phoenix Scientific Industries Ltd. 14

Raymor Industries Inc 11

Seco/Warwick S. A. 15

Tisoma Anlagenbau und Vorrichtungen GmbH 19

TOPMIM International Limited 6

Winkworth 23

Yuelong Superfine Metal Co, Ltd. 10


2010 International Conference on Powder Metallurgy & Particulate Materials

June 27–30The Westin DiplomatHollywood (Ft. Lauderdale), Florida

For complete program and registration information contact:METAL POWDER INDUSTRIES FEDERATION ~ APMI INTERNATIONAL105 College Road East, Princeton, New Jersey 08540 USATel: 609-452-7700 ~ Fax: 609-987-8523 ~ www.mpif.org

FINAL 2010 AD.euro_Layout 1 2/2/2010 11:23 AM Page 1

International: powder injection moulding.� If you wish to

produce complex ceramic and metal products using the PIM process, then come to the leading inter-

national specialists in this field: ARBURG. For you, we have the appropriate ALLROUNDER machine

technology and the required know-how from our PIM laboratory. With our expertise, you will be able

to manufacture efficiently and to the highest quality, prepare material, injection-mould components,

debind and sinter - finished! You want to find out more about PIM processing? Simply talk to us!

ww

w.a

rbur

g.co

m

ARBURG GmbH + Co KGPostfach 11 09 · 72286 Lossburg/GermanyTel.: +49 (0) 74 46 33-0Fax: +49 (0) 74 46 33 33 65e-mail: [email protected]

If you wish to International: powder injection moulding. · e-mail: [email protected] cover...

Documents

Transcript of If you wish to International: powder injection moulding. · e-mail: [email protected] cover...