MIM DesignGuide

DESIGN GUIDEMIM Metal Injection Molding

PHILLIPS PLASTICS CORPORATION™

http://phillipsplastics.com/case_studies/71/metal-injection-molding

Serving original equipment manufacturers invirtually every market since 1964, Phillips PlasticsCorporation™ has established itself as one of thepremiere sources for the design and manufactureof custom plastic and metal injection moldedcomponents. Today, Phillips Plastics employsover 1,600 people in 15 locations throughoutthe United States.

Phillips Plastics Corporation™

phillipsmetals.com

http://phillipsplastics.com/case_studies/case-studies/interface-135-metal-injection-molding

What is Metal Injection Molding?Metal injection molding (MIM) is an effective way to produce complex and precision-shaped parts froma variety of materials. It is common for this process to produce parts for 50% less than the cost of CNCmachining or investment casting. At the same time, the true value of MIM comes from its ability to produceparts with complex shapes, superior strength, and excellent surface finish in combination with high volumemanufacturing capability. Total cost savings result from the function of shape complexity, production volumes,size of the part, and material used. Sizes of parts can be up to 150 grams, although most parts produced areless than 30 grams.

The Smaller Side Of MIM

Phillips Plastics can meet your smallest

requirements, with the capability to mold

metal parts in a variety of materials ranging

from 0.0001 - 0.003 cubic inches. Tolerances

can be held to as little as ±0.0005 inches.

http://phillipsplastics.com/capabilities/micro-molding

1. Feedstock MixingAttention to detail at the mixing step is critical toensure the homogeneity of the feedstock over thelong run. MIM feedstock begins with extensive char-acterization of very fine (less than 22 micron) metalpowders. These powders are carefully hot mixedtogether with polymeric binders to form a uniformmixture. This mixture is then cooled and granulated toform the feedstock for the injection molding machine.

2. MoldingPhillips’ specially equipped injection moldingmachines are designed to mold a metal/polymerfeedstock. Combining over 42 years of injectionmolding experience with advanced processinginstrumentation and software ensures tight control ofthis process producing consistent components withunvarying density. If in-cavity pressure transducersindicate the molding cycle is out of predeterminedlimits, the closed loop feedback system rejects parts automatically.

Most of the advantages of using Phillips’ MIM capabilities are realized in the molding step, wherecomplex contours, holes, small radii, logos, and textcan be molded in. The molding process creates virtuallyno waste since runners can be reground and moldedagain without compromising the properties of the finalpart. In the molding area, extensive automation is alsoemployed to palletize parts directly onto ceramic setters.This automation eliminates the unnecessary handlingof parts, providing consistent and cost-effectivemanufacturing solutions.

3. Catalytic DebindingThe advanced debinding technology used by Phillipsis the most efficient form of debinding. Harnessingthe power of polymer chemistry, Phillips introducesa catalyst to remove 90% of the binder from the greenpart. Because catalytic debinding occurs at tempera-tures below the softening point of the binder, partsare processed with excellent shape and dimensionalintegrity. After the binder has been removed, the resultis termed a “brown” part. The brown part consists ofa porous matrix of metal powder and a small amountof binder, sufficient to allow the part to retain its shape.

There are four primary steps,which utilize fourkey processes toproduce metalinjection moldedparts with superiorquality and dimensionalrepeatability:

The MIMProcess

4. SinteringIn the final step, the brown parts are sintered using a temperature and atmosphere profile chosenspecifically for the alloy being processed. At the lowertemperatures of the sintering cycle, the residual poly-mer binder is removed. As the temperature increases,sintering begins. Neighboring particles fuse and bondto one another bringing the structure together andreducing porosity. Ultimately, the required physicalproperties are obtained and densities between 96-99%of theoretical are achieved. During the densificationprocess, depending on the material being processed,liner shrinkage of 14-22% occurs. This shrinkage ispredictable and compensated for by over-sizing themold cavity. Typical as-sintered tolerances are within± 0.30 to 0.50 (0.003 to 0.005 inches-per-inch).

Benefits of Metal Injection Molding

MIM can produce relatively small, highly

complex geometries with excellent surface

finish, high strength, and superior corrosion

resistance. Parts that are well suited for MIM

are those that would require extensive

machining set-up or assembly operations

if made by any other metal forming process.

The major advantage of MIM is its ability to

produce complex metal geometries without

machining. If the designer begins work at the

concept stage, overall part size and weight can

be reduced and multiple components can be

consolidated into a single design. By designing

components for the MIM process, part count

and assembly time are reduced resulting in

overall cost savings.

Stepping Through theProcess

1 “Green” or “as molded” parts

2 “Brown” parts. Same size, but90% of the binder is gone

3 “Sintered” parts. 96+% dense.Size meets print

1

2

3

Metal Injection Molding

FeedstockPreparation

· Powder and polymer binderare hot mixed to produce ahomogenous mixture

Molding PropertiesCompared to PlasticsMolding

Feedstock· Viscosity of feedstock

is much higher· Feedstock density 5-6 g/cm3

· Advanced instrumentation is required for process monitoring and control

Mixing and Pelletization Molding Debinding

Polymer(~ 40% volume)

Feedstock

HeaterBands

Exhaust Burner

HeaterCoils

Mold

Metal Powder(~ 60% volume)

DebindCharacteristics

Process Parameters· Chemical reaction· Shrinking core mechanism· Temperature is below

softening point of binder

Process Keys· Fast (2-4 hours)· Clean· No distortion of parts

SinteringCharacteristics

· Linear shrinkage of 14-22%

· Sintered density of 96-99% of theoretical

· Mechanical and corrosionproperties comparable towrought

Catalytic Debinding Sintering

ust Burner

Shrinking Core MechanismContinuous Furnace

8-10 Preheat and Hot Zones

SecondaryBinder

Brown Parts

SinteredParts

Fan

Catalyst

Total Solutions

For over four decades, Phillips has been

providing OEMs with design, manufacturing,

and post-molding services. Phillips offers the

rare advantage of a true “one-stop shop.” With

a full complement of metal, plastic, and mag-

nesium injection molding expertise, the best

process is selected for each component.

Phillips’ cross-functional team of manufacturing

experts combines forces to promote effi-

ciencies in manufacture and assembly such

as insert molding metal components with

plastic, designing attachment features for

the most effective assembly, and providing

comprehensive secondary services – from

painting to shielding and assembly.

Quality ComponentsThe Phillips MIM process ensures customers receivesuperior quality components in the most compressedtime frame possible. Time reductions are achieved byutilizing resins that can undergo debinding five timesfaster than those used by other metal injection molders.In addition, part designs are optimized and mechanicalproperties ensured with Phillips’ product design anddevelopment capabilities, which are supported by anexpert staff of metallurgists and engineers. Whetherprototype quantities or millions of parts are required,Phillips follows the same quality procedures accordingto their TS16949: 2002, ISO 14001, and ISO 9001: 2000 registrations.

Tooling ExpertiseMIM molds are similar to those used for plasticinjection molding. As in tooling for plastic injectionmolding, molds are often designed with multiplecavities to reduce processing costs. Phillips’ in-housetooling capabilities can be employed to ensure a seam-less line of communication during the tooling phaseof the program. Although lead times vary from oneprogram to another, typical MIM tooling lead timesare 4-8 weeks. A Phillips representative can assist in determining the cost-effectiveness for individual programs.

Advantages of Phillips’ MIM Process

Flexible CapabilitiesPhillips’ metal injection molding facility is equippedwith both batch and continuous debinding ovens andsintering furnaces. Continuous debinding and sinteringprovides the temperature uniformity and consistentprocessing conditions for a wide range of materials.The result is excellent dimensional repeatability at thelowest possible cost for programs with extremelyhigh throughput requirements.

Batch sintering compliments Phillips’ continuousfurnace capability by providing the flexibility to runsmaller batch sizes in product development cycles.Batch sintering also allows Phillips to run larger parts,in the 120 grams range or higher, that would not bewell suited for the continuous furnace process. Inaddition, with the vacuum capabilities of these furnaces, specialty materials like titanium can be processed.

AutomationExtensive automation is employed to maintain constant cycle times and minimize part handling.Consistency and a lower overall cost to customersare the results.

Phillips’ batch debind ovens and furnaces are equipped tohandle a wide variety of MIM materials

In A Flash

Phillips’ reputation for producing high quality

parts in an accelerated time frame begins at

the design phase of a program. At one of

two in-house design development centers,

Phillips’ team can create high quality MIM

parts in as little as two weeks.

Benefits of Phillips’ MIM Process Include:

· Superior quality

· Consistent processing

· Shortened lead times

· Optimized part designs

· Superior mechanical properties

· Sampling and prototyping

As a one-stop solution provider, Phillips Plastics

offers the following corporate-wide capabilities

to supplement all MIM programs:

· Design Development Centers utilize all major CAD

platforms

· Industrial design

· Engineering

· Finite element analysis (FEA)

· Moldflow® analysis

· Rapid prototyping

· Stereolithography

· Insert molding

· Medical molding and assembly

· Multi-shot molding

· Precision decorating

· Low volume molding

· Small parts molding

· Magnesium injection molding

· Micro molding

· Program management

· Supply chain management

· In-house automation

· Three in-house toolrooms

· Clean room molding

Phillips’ continuous debinding and sintering furnaceprovides quality processing and large volume capacity

while maintaining consistent quality

Traditional Metalforming Processes –Where MIM FitsOne of the more traditional metalforming processes,MIM competes on a material and geometry basisdirectly with investment casting and machining. Inother words, similar geometries can be produced in a given material by each of these three processes.MIM excels when part complexity is high, overallcomponent size is small, and production volumesare 10,000 or more.

MIM competes against die-casting on a geometry-onlybasis. Here, the same geometries can be produced byboth processes, but material choices are different.Compared with aluminum, zinc, or magnesium diecastings, MIM components offer far superior strength,hardness, and corrosion resistance properties. In mostcases, the higher properties of MIM come at a slightlyhigher cost when compared to die-cast components.

MIM may compete economically with stamping or theconventional powder metal process when two or moreof these components are combined into a single MIMdesign. By reducing part-count and eliminating assem-bly hassles, a lower overall cost can be achieved. Thegreater design flexibility of MIM allows features likeblind holes, threads, and wall thickness changes tobe molded-in from the start rather than added lateras secondary operations.

The following are guidelines for choosing metal injection molding over an alternative metal forming process:

· MIM designs save material and weight

· Cost savings

· Molding components from a single tool

eliminates multiple set-up operations

· Difficult to machine materials can be

molded into shape

· MIM can produce thinner wall sections

and sharper cutting points

· Better surface finish

· Better for small diameter blind and

through holes

· Finish machining required is greatly reduced

· High volumes of small components are

produced at lower cost and faster lead times

· MIM alloy selections offer superior

corrosion protection

· Superior wear resistance

· Superior strength and hardness

· Larger material selection

· MIM can mold geometries that eliminate

secondary operations

· Superior density and corrosion performance

· Superior strength and ductility

· Combining two P/M parts can reduce

part count

· Superior magnetic properties

Benefit of Choosing MIMAlternative Metalforming Process

Machining

Investment Casting

Die-Casting

Press and Sinter

Reasons for Choosing MIM

DesignConsiderationsWhen designing MIM components, the engineer canbegin with a clean slate, adding material in uniformwall sections only when needed. This thought processis much different than designing for machining, wherereducing the amount of metal removed from a squareor round stock can be an important consideration.Because MIM allows the designer to reduce materialcontent to only what is functionally required, MIMparts are generally smaller and lighter than theirmachined counterparts.

The MIM designer is also freed from the restrictionsimposed by the capability of the machining equipment.The design freedom with MIM is largely the same aswith plastic injection molding. Whether the designermakes improvements by reducing material content,combining multiple components, or by molding intext and logos, the earlier Phillips’ MIM engineersare involved, the greater the chance to experiencethe full benefits of metal injection molding.

Parts Appropriate for MetalInjection Molding

· Complex geometries – parts requiring

multiple machining operations are usually

good candidates for MIM

· Tolerances ±0.003” to 0.005” per inch

· 150 grams or less in weight, although most

MIM parts are less than 30 grams

· Length of components – less than five

inches

· Capability to support various volumes from

concept to high volume production

DraftOn complex shapes where draft is required, the normalrange is 0.25 to 0.50 degrees. In many cases, parts canbe produced with no draft.

Wall ThicknessTo avoid internal stresses, voids, and sink marks, wallsof uniform thickness are ideal. Thicknesses in the rangeof 0.050 to 0.250 inches are preferred, but exceptionsin both directions are routinely done. Parts have beenproduced with wall sections as little as 0.005 inchand as large as 0.50 inch. Consult a Phillips’ metalinjection molding engineer for details.

Ribs and WebsRibs and webs are useful for reinforcing relativelythin walls and avoiding thick sections. They improvematerial flow and limit distortion, while increasingstrength and rigidity of a thin wall. Rib thicknessshould not exceed that of the adjoining wall.

Fillets and RadiiFillets and radii eliminate sharp corners, which reducesstress at the intersection of features and facilitates theflow of feedstock into the mold cavity.

Design Features The design features that can be madeby MIM are similar to those made by conventional plasticinjection molding or die-casting.

UndercutsExternal undercuts can be formed anywhere in the part. Internal undercuts can be formed using col-lapsible cores, but they are generally not consideredeconomically practical. Phillips has the capability tomachine internal undercuts as a secondary operation,when required.

ThreadsExternal and internal threads can be molded usingMIM technology; however, secondary tapping is usuallymore precise for internal threads. External threads arenormally produced with a small flat area on the partingline of the mold to eliminate potential interferencefrom the parting line.

Design ConsiderationsWhen designing for the MIM process,engineers should be aware of the following requirements of the molding process:

Parting Line – The parting line is the plane

in which the two mold halves meet. To the

extent possible, all features should be oriented

perpendicular to the plane of the parting line

to facilitate removing the part from the mold.

Slides and lifters can be incorporated for

components that cannot be perpendicular

to the parting line

Gate Location – The optimum location of gates

is a balance between product and processing

requirements. In general gates should be

positioned to direct the flow onto a core pin

or cavity wall. Where wall thickness varies,

gates should be located so the material flows

from the thicker to the thinner sections.

Witnesses – Because a MIM component

begins as an injection molded part, witnesses

such as parting lines, ejector pins, and gates

will be present. When designing critical fea-

tures into a part, consideration of the location

of witnesses should be addressed with

Phillips’ team of experts.

Provisions for Sintering – Metal injection

molded parts are typically placed on flat,

ceramic fixtures for sintering. Parts with long

cantilevers and spans are not self-supporting

and generally require ribs, added supports,

or custom fixtures for sintering. Whenever

possible, the part designs should include a

flat surface to eliminate the need for these

custom fixtures. For more complex shapes,

custom setters can be utilized for highly

detailed geometries.

SecondaryOperationsPhillips can provide secondary operations to meet anarray of specific requirements. Since typical tolerancesfor the MIM process are within 0.003 to 0.005 inchesper inch, (0.3-0.5%), many parts are sintered to finaldimensions. If tighter tolerances are required in cer-tain areas, secondary-machining operations can beapplied. Tapping operations can produce internalthreads with tolerances tighter than can be achievedvia the metal injection molding process. Tumbling andpolishing can provide an aesthetic surface. Parts canbe heat-treated; black oxide coated, and plated insimilar fashion to investment cast or machined parts.

Secondary operations offered byPhillips’ Metal Injection Moldinginclude:

· CNC Machining

- Milling

- Turning

- Grinding

- Tapping

- Lapping

· Surface finishing

- Passivation

- Black oxide

- Nickel

- Gold

- Chrome

- Bead blasting

- Tumbling

- Electro-polishing

- Titanium nitride

· Calibration

- Coining

- Sizing

- Straightening

· Heat Treatment

- Through hardening

- Case hardening

- Annealing

- Ageing

- Tempering

MaterialsTesting and Measurement

Phillips’ in-house metallurgy lab provides

material characterization and testing services,

including tensile testing, fatigue testing,

microstructure analysis, hardness, density,

corrosion testing, and carbon analysis. Full

geometric inspection with Statistical Process

Control (SPC) is available for all components.

These capabilities allow Phillips to maintain

tight control of all aspects of the MIM process.

Go to phillipsmetals.com for the most up-to-date material selection chart

Phillips’ Metal Injection Molding offers several alloysthat are used in a wide variety of automotive, electronic,medical, magnetic, and consumer applications.Injection molded alloys include:

· Stainless steels · Titanium· Tool Steels· Low alloy steels· Soft-magnetic alloys · Controlled expansion alloys· High temperature alloys

Phillips metallurgist testing the strength of materials andmechanical properties

Phillips Plastics Corporation At A Glance

· Established in 1964, Phillips Plastics is a privately held

custom injection molder of plastic and metal

· Phillips Plastics is a technology driven Company, providing

contract manufacturing services to original equipment

manufacturers in the automotive, appliance, telecommu-

nications, consumer electronics, industrial, medical,

defense, and recreational markets

· Fiscal year 2005 sales were approximately $220 million

· Phillips Plastics employs more than 1,600 people; supported

by a network of 814 production people, 31 quality assurance

people, 20 designers, 166 engineers (includes design,

process, and manufacturing), and 115 toolmakers (includes

tool managers, coordinators, team leaders, mold makers,

mold polishers, machinists, jig and fixture, EDM specialists,

and apprentices)

· Total number of presses is 254, ranging in tonnage

from 0.44 to 935

· Phillips Plastics consists of 15 locations throughout

the United States, occupying over 718, 737 square feet,

with total manufacturing square footage equaling

333,658 square feet

· Facilities are certified to ISO 9001, ISO 9002, ISO

9001:2000, ISO 13488, TS-16949, and ISO 14001. Our

medical facilities are registered with the FDA for medical

device manufacturing. Facility certificates will be supplied

upon request


Opportunity [email protected]

phillipsmetals.com


Typical Mechanical Properties of Metal Injection Molded Alloys

Material Yield Strength(MPa)

UTS(MPa)

Elongation (%) Density(g/cm3)

Hardness(HRC)

Low Alloy Steels

42CrMo4(4140)as-sintered

42CrMo4(4140)heat treated

8620

8620heat treated

4605as-sintered

4605heat treated

Fe-2% Nias-sintered

Fe-2% Niheat treated†

Fe-8% Nias-sintered

Fe-8% Niheat treated†

Stainless Steels

316L

310N2 sintered

PANACEA

17-4PHheat treated

420heat treated

440 B(sinc and HIP)

440 Bheat treated

!400

!1250

!400

!400

1500

!150

!210

!180

!450

!690

!950

!1300

!650

!1450

!650

!600

1900

!260

!380

!510

!600

!1090

!1100

!1600

!7.4

!7.4

!7.4

!7.4

!7.55

!7.55

!7.5

!7.5

!7.5

!7.5

!7.8

!7.22

!7.50

!7.6

!7.3

!7.65

!7.65

130-230 HV10

!45 HRC

190-230 HV10

!650 HV1

!150 HV1

!55 HRC

90-110 HV10

!55 HRC

90-140 HV10

!600 HV10

120 HV10

235 HV1

270-300 HV10

38 HRC

!48 HRC

!45 HRC

!55 HRC

!3

!2

!3

!5

!2

!25

!15

!50%

16

!35

!5

!2

† Refers to typical properties for through-hardened Fe-2% Ni and Fe-8% Ni. These alloys can be heat-treated to achieve a range of case or through hard-ness depending on the application. The corresponding strengths and ductilities vary depending on the heat-treated condition.

1 Mpa = 145 psi

Note:All properties are typical. Phillips’ Metal Injection Molding does not warranty that these materials are fit for any particular purpose. All materials need tobe tested by the customer to assure they meet minimum performance criteria.

©2006 PHILLIPS PLASTICS CORPORATION™


Typical Mechanical Properties of Metal Injection Molded Alloys

Material Yield Strength(MPa)

UTS(MPa)

Elongation (%) Density(g/cm3)

Hardness(HRC)

Tool Steel

M2as-sintered

M2heat-treated

Soft Magnetic Alloys

Fe-50% Ni

F (pure iron)

Fe-3% Si

430

Special Alloys

HX (Hastelloy X)sintered and solution annealed)

Titanium(CP Grade 4)

Kovar® (F15)

Tungsten (W)non-magnetic

!800

!150

!110

!300

!200

!280

!480

!300

!1200

!400

!230

!500

!350

!610

!550

!450

!7.9

!7.9

!7.6

!7.8

!7.5

!7.6

!7.87

!4.2

!7.8

!17.8

!50 HRC

!64 HRC

100-140 HV1

50-60 HV10

120-160 HV1

100-150 HV10

140-160 HV10

160-240 HV1

110-140 HV1

320 HV1

!1.0

!20

!40

!20

!30

!35

!5

!24

1 Mpa = 145 psi


Kovar® is a registered trademark of Carpenter Technology Corporation



Nominal Chemical Composition (%) of Metal Injection Molding Alloys

Material Fe Ni Cr C Others

Low Alloy Steels

42CrMo4(4140)

8620

4605

Fe-2% Ni

Fe-8% Ni(sintered in H2)

Fe-8% Ni(sintered in N2)

Stainless Steels

316L

310

PANACEA

17-4PH

420

440 B

Tool Steel

M2

Soft Magnetic Alloys

Fe-50% Ni

F (pure iron)

Fe-3Si

430

Special Alloys

HX (Hastelloy X)

Titanium (CP Grade 4)

Kovar® (F15)

Tungsten (W)

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

17-20

Bal.

0.4-0.7

1.50-2.50

1.90-2.20

7.50-8.50

7.50-8.50

10-14

19.0-22.0

"0.10

3-5

49.5-50.5

Bal.

28.5-29.5

0.32-0.42

0.12-0.23

0.40-0.60

"0.10

"0.10

0.4-0.6

0.03 max

0.2-0.5

"0.20

0.07 max

0.18-0.30

0.75-0.95

0.95-1.05

"0.10

"0.10

"0.10

"0.08

0.05-0.15

"0.20

Si

1.0 max

1.0 max

0.75-1.75

"1.0

1.0 max

"1.0

"1.0

2.50-3.00

"1.0

"1.0

Mo

0.15-0.30

0.15-0.30

0.20-0.50

2.0-3.0

3.0-3.5

"0.75

4.5-5.5

8-10

Cu

3.0-5.0

Mn

2.0 max

"1.5

10-12

1.0 max

"1.0

"1.0

"1.0

"1.0

1.2-1.5 Nb

0.75-0.90 N

0.15-0.45 (Nb + Ta)

W 5.50-6.75 V 1.75-2.20

0.5-2.10 Co, 0.20-1.0 W, 0.008 B

Ti Bal. (O " 0.40, N " 0.10)

Co 16.5-17.5

"94% W Bal. (Ni, Cu, Co)

0.9-1.2

0.4-0.6

16-18

24.0-26.0

16.5-17.5

15-17.5

12-14

16-18

3.80-4.50

49.5-50.5

15.5-17.5

20.5-23.0

Kovar® is a registered trademark of Carpenter Technology Corporation



Typical Magnetic Properties of Metal Injection Molded Soft-Magnetic Alloys

New Special Alloys

Material

Yield Strength UTS Elongation Density Hardness

C Cr Fe Co Al Ti Mn Si Ni

Material C Si Mn Cr Ni Mo V W Fe


1 Oerstad (Oe) = 79.55 ampere/meter (A/m)1 kiloguass (kG) = 0.10 tesla (T)


ResidualInduction

CoerciveForce

MaximumPermeability

InducedMagnetic

Field

InducedMagnetic

Field

InducedMagnetic

Field

Fe-50% Ni

F (Pure Iron)

Fe-3% Si

430

8

12.4

11.5

6.4

0.125

0.36

0.918

0.92

14

12.4

11.5

6.4

8

15.7

14.9

12

14.6

NA

NA

--

27,270

14,236

5,215

3,311

Br(kG)

Hc(Oe)

µmax(B/H)

B25(kG)

B50(kG)

B500(kG)

Nimonic 90

after sintering

CHS-4

after sintering at 20˚C

sintered + heat-treated

HIP + heat-treated

"0.13 18-21 "1.5 15-21 1.0-2.0 3.0-4.0 "1.0 "1.0 Bal.

730 MPA

790

1220 MPA

1270

14

33

8.0

8.18

350 HV10

385 HV10

Yield Strength UTS Elongation Density Hardness

2.2 1.6 1.0 12.0 39.0 6.0 0.9 0.5 Bal.

"600 MPA "800 MPA "2.0 "7.9 "33-37 HRC

MIM DesignGuide

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