Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 10094 (1998): Code of practice for pattern making byusing expanded polystyrene material [MTD 14: Foundry]

PATTERNMAKINGBYUSING EXPANDEDPOLYSTYRENEMATERIAL-

CODEOFPRACTICE

( First Revision )

TCS 25.120.30 : 8X080.20

0 BIS 1998

BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

September 1998 Price Croup 1

Foundry Sectional Committee, MTD 14

FOREWORD

This Indian Standard (First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized by the Foundry Sectional Committee had been approved by the Metallurgical Engineering Division Council.

This standard was first published in 198 I. While reviewing the standard, the committee decided to revise it to align with the present practices being followed by the industry.

The use of expanded polystyrene material has progressively increased in the recent years inthe Indian foundries for jobbing work and small batch production. The material is particularly useful for complex shapes of patterns. This standard prescribes Code of practice for using expanded polystyrene material for pattern making and moulding.

IS loo94 : 1998

Zndian Standard

PATTERNMAKINGBYUSING EXPANDEDPOLYSTYRENEMATERIAL-

CODEOFPRACTICE

( First Revision )

1 SCOPE

This standard describes the code of practice for pattern making and moulding by using expanded polystyrene material.

2 MATERIAL

2.1 Expanded polystyrene used for pattern work shall have a density in the range of 20 kg/m3 to 30 kg/m3. The material having density less than 20 kg/m’, being very soft and porous, is not suitable for casting work. In case where the pattern made in expanded polystyrene is to be used as a gasifiable material namely for full mould casting, its residual content (obtained after burning at 600°C for 15 min) shall not be more than 0.20 percent.

2.2 Expanded polystyrene is obtained in the form of slabs in varying lengths, widths and thicknesses and also in the form of preformed beads.

3 CODE OF PRACTICE FOR PATTERN MAKING

3.1 Expanded polystyrene pattern may be made in any pattern shop which can make wooden patterns. It is easily machined with hand tools or on wood-working machine tools. It may be sawn, sharp knived, planed, miled or sanded using high spindle speeds. Polystyrene sawn with an ordinary band saw has a poor finish. Better results are obtained by cutting with a band saw from which the teeth have been broken off and remaining edge sharpened. It may also be easily machined with a hot tool, more particularly with a nichrome wire (about 0.5 to 0.8 mm diameter) heated electrically by passing a dc current at 24 volts.

3.2 While preparing patterns, necessary allowances are given for the metal shrinkage and machining. When the pattern is to be used for full mould casting, no draft is required, otherwise suitable taper shall be given if it is required to be withdrawn from the mould for re-use. The accuracy of the castings, as for castings made from wooden patterns, is conditioned by the accuracy of the patterns themselves.

3.3 The pattern may be composed of separate parts glued together with a formaldehyde glue or any special

glue which does not dissolve the plastic. The glue is to be applied in a thin layer on the surfaces of the parts, with a wooden spatula. Excessive adhesive may cause defects in castings as any unburnt residue will form a slag. Small parts of the pattern can be bonded together immediately after the adhesive is applied but the larger sections should be left to stand for lo-15 min after application and then clamped together. A smooth overall surface may be obtained further by finishing with sand paper and by sealing the pattern joints and odd flaws with gummed paper strip. Small fillets may also be formed from this strip. Large fillets should be made in polystyrene. Massive patterns may be made hollow, to reduce gas formation.

3.4 When batch type full mould castings are to be made, patterns may be moulded using polystyrene raw material or prefoamed heads, by heating with steam or hot air and water cooling in specially made metallic moulds (see Fig. 1). Close control is required in the process to ensure proper moulding operation. At times, combination of all the above processes could be adopted to get full mould patterns.

4 CODE OF PRACTICE FOR MOULDING

4.1 The moulding sand mixes used with expanded polystyrene patterns shall be such that the need for ramminng is minimum. Thus, no-bake or air-hardening sand mixes based on sodium silicate or organic compounds, like phenolics, amino plastics or furan may be quite suitable. Fluid sand mixes may be further advantageously used.

4.1.1 Sufficient mould permeability shall be maintained for the gases to come out.

4.1.2 Clean dry sand may also be used with the full mould -process because the expandable pattern supports the sand, until it is replaced by metal. Unbonded sand is compacted around the pattern by gravity, by vibration, by jolting and by confining the sand to form a rigid structure. As the pattern is replaced by molten metals, the resulting gas pressure, the condensed product of vaporization, and the metal itself, all combine to support the sand and maintain the rigid structure of the mould. Running and feeding system may also be made of the same material.

KS 10094 : 1998

1. Raw materia! 5. Storage bin 2. Prefoamer 6. Pattern forming machine 3. Slever 7. Pattern 4. Pneumatic conveyor 8. Getting complicated pattern by gluing

Flc.1 SCHEMATICDIAGRAM- MOULDINGOFPOLYSTYRENEPATTERNS

4.2 The dressed polystyrene pattern is set on a pattern plate or level floor in moulding box and fitted wifh a polystyrene gating system, preferably having a ceramic sprue. The pattern is then covered with air hardening moulding sand and all cavities, pockets and the whole surface are carefully packed by hand with a layer of sand at least 50-75 mm thick. The rest of the box is filled with ordinary moulding sand and rammed. The box is then inverted and other side of the box moulded in a similar way. Vents are pierced from top. If the pattern is to be removed the boxes may be opened, pattern withdrawn if possible, or chiseled out or burnt with a gas torch and the boxes closed again.

The pouring basin is then set and the metal poured. The polystyrene gasifies as soon as the molten metal comes in contact with it and escapes from the mould.

4.3 In full mould casting, cores are dispensed with in a majority of cases. If necessary, these are passed through the polystyrene pattern, the print portion hanging out which goes into the moulding sand.

4.4 For small castings, top gating or parting gating can be used but for heavy ones, bottom gating is recommended.

2

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country.

Copyright

BIS has the copyright of all its publications. No part of these_publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards: Monthly Additions’.

This Indian Standard has been developed from Dot : No. MTD 14 ( 3974 ).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

BUREAU OF INDIAN STANDARDS

Headquarters:

Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110 002 Telegrams : Manaksanstha

Telephones : 323 01 3 1,323 33 75,323 94 02 (Common to all offices)

Regional Offices :

Central : Manak Bhavan, 9 Bahadur Shah Zafar Marg NEW DELHI 110 002

Eastern : l/14 C. I.T. Scheme VII M, V. I. P. Road, Maniktola CALCUTTA 700 054

Northern : SC0 335-336, Sector 34-A, CHANDIGARH 160 022

Southern : C. I. T. Campus, IV Cross Road, CHENNAI 600 113

Western : Manakalaya, E9 MIDC, Marol, Andheri (East) MUMBAI 400 093

Telephone

1

323 76 17 323 38 41

{

337 84 99,337~85 61 337 86 26,337 91 20

I

60 38 43 60 20 25

1

235 02 16,235 04 42 235 15 19,235 23 15

832 92 95,832 78 58 8327891,8327892

Branches : AHMADABAD. BANGALORE. BHOPAL. BHUBANESHWAR. COIMBATORE. FARIDABAD. GHAZIABAD. GUWAHATI. HYDERABAD. JAIPUR. KANPUR. LUCKNOW. NAGPUR. PATNA. PUNE. THIRUVANANTHAPURAM.

DGvtad at Printograph, New Delhi, Ph : 5726847