mim design guide metal injection molding - … · metal injection molding (mim) ... requirements,...

DESIGN GUIDEMIMMetal Injection Molding

PHILLIPS-MEDISIZE CORPORATION

Serving original equipment manufacturers in virtually every market since 1964, Phillips-Medisize Corporation has established itself as one of the premiere sources for the design and manufacture of custom plastic and metal injection molded components. Today, Phillips-Medisize employs over 3,100 people in 14 locations throughout the United States, Europe, Mexico and China.

Phillips-Medisize Corporation

phillipsmedisize.com

What is Metal Injection Molding? Metal injection molding (MIM) is an effective way to produce complex and precision-shaped parts from a variety of materials. It is common for this process to produce parts for 50% less than the cost of CNC machining or investment casting. At the same time, the true value of MIM comes from its ability to produce parts with complex shapes, superior strength, and excellent surface finish in combination with high volume manufacturing 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 are less than 30 grams.

The Smaller Side Of MIM

Phillips-Medisize 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.

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

2. MoldingPhillips-Medisize’s specially equipped injection molding machines are designed to mold a metal/polymer feedstock. Combining over 42 years of injection molding experience with advanced pro-cessing instrumentation and software ensures tight control of this process producing consistent compo-nents with unvarying density. If in-cavity pressure transducers indicate the molding cycle is out of pre-determined limits, the closed loop feedback system rejects parts automatically.

Most of the advantages of using Phillips-Medisize’s MIM capabilities are realized in the molding step, where complex contours, holes, small radii, logos, and text can be molded in. The molding process cre-ates virtually no waste since runners can be reground and molded again without compromising the proper-ties of the final part. In the molding area, extensive automation is also employed to palletize parts directly onto ceramic setters. This automation eliminates the unnecessary handling of parts, providing consistent and cost-effective manufacturing solutions.

3. Catalytic DebindingThe advanced debinding technology used by Phillips-Medisize is the most efficient form of debind-ing. Harnessing the power of polymer chemistry, Phillips-Medisize introduces a catalyst to remove 90% of the binder from the green part. Because cata-lytic debinding occurs at temperatures below the softening point of the binder, parts are processed with excellent shape and dimensional integrity. After the binder has been removed, the result is termed a “brown” part. The brown part consists of a porous matrix of metal powder and a small amount of binder, sufficient to allow the part to retain its shape.

There are four primary steps, which utilize four key processes to produce metal injection molded parts with superior quality and dimensional repeatability:

The MIM Process

4. SinteringIn the final step, the brown parts are sintered using a temperature and atmosphere profile chosen specifically for the alloy being processed. At the lower temperatures of the sintering cycle, the residual poly-mer binder is removed. As the temperature increases, sintering begins. Neighboring particles fuse and bond to one another bringing the structure together and reducing porosity. Ultimately, the required physical properties are obtained and densities between 96-99% of theoretical are achieved. During the densification process, depending on the material being processed, liner shrinkage of 14-22% occurs. This shrinkage is predictable and compensated for by over-sizing the mold 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 corro-

sion 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 the Process

1 “Green” or “as molded” parts

2 “Brown” parts. Same size, but 90% of the binder is gone

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

1

2

3

Metal Injection Molding

Feedstock Preparation

· Powder and polymer binder are hot mixed to produce a homogenous mixture

Molding Properties Compared to Plastics Molding

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

Heater Bands

Exhaust Burner

Heater Coils

Mold

Metal Powder (~ 60% volume)

Debind Characteristics

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

Sintering Characteristics

· Linear shrinkage of 14-22%

· Sintered density of 96-99% of theoretical

· Mechanical and corrosion properties comparable to wrought

Catalytic Debinding Sintering

Exhaust Burner

Shrinking Core MechanismContinuous Furnace

8-10 Preheat and Hot Zones

Secondary Binder

Brown Parts

Sintered Parts

Fan

Catalyst

Total Solutions

For over four decades, Phillips-Medisize

has been providing OEMs with design,

manufacturing, and post-molding services.

Phillips-Medisize offers the rare advantage

of a true “one-stop shop.” With a full comple-

ment of metal, plastic, and magnesium

injection molding expertise, the best process

is selected for each component. Phillips-

Medisize’s cross-functional team of manufac-

turing experts combines forces to promote

efficiencies in manufacture and assembly

such as insert molding metal components

with plastic, designing attachment features

for the most effective assembly, and provid-

ing comprehensive secondary services –

from painting to shielding and assembly.

Quality ComponentsThe Phillips-Medisize MIM process ensures custom-ers receive superior quality components in the most compressed time frame possible. Time reductions are achieved by utilizing resins that can undergo debinding five times faster than those used by other metal injection molders. In addition, part designs are optimized and mechanical properties ensured with Phillips-Medisize’s product design and development capabilities, which are supported by an expert staff of metallurgists and engineers. Whether prototype quantities or millions of parts are required, Phillips-Medisize follows the same quality procedures accord-ing to their TS16949: 2002, ISO 14001, and ISO 9001 registrations.

Tooling ExpertiseMIM molds are similar to those used for plastic injec-tion molding. As in tooling for plastic injection mold-ing, molds are often designed with multiple cavities to reduce processing costs. Phillips-Medisize’s in-house tooling capabilities can be employed to ensure a seamless line of communication during the tooling phase of the program. Although lead times vary from one program to another, typical MIM tooling lead times are 4-8 weeks. A Phillips-Medisize repre-sentative can assist in determining the cost-effec-tiveness for individual programs.

Advantages of Phillips-Medisize’s MIM Process

Flexible CapabilitiesPhillips-Medisize’s metal injection molding facility is equipped with both batch and continuous debinding ovens and sintering furnaces. Continuous debinding and sintering provides the temperature uniformity and consistent processing conditions for a wide range of materials. The result is excellent dimensional repeatability at the lowest possible cost for programs with extremely high throughput requirements.

Batch sintering compliments Phillips-Medisize’s continuous furnace capability by providing the flexibility to run smaller batch sizes in product development cycles. Batch sintering also allows Phillips-Medisize to run larger parts, in the 120 grams range or higher, that would not be well suited for the continuous furnace process. In addition, 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 customers are the results.

Phillips-Medisize’s batch debind ovens and furnaces are equipped to handle a wide variety of MIM materials

In A Flash

Phillips-Medisize’s 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-Medisize’s

team can create high quality MIM parts in

as little as two weeks.

Phillips-Medisize’s continuous debinding and sintering furnace provides 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 basis directly with investment casting and machining. In other words, similar geometries can be produced in a given material by each of these three processes. MIM excels when part complexity is high, overall component size is small, and production volumes are 10,000 or more.

MIM competes against die-casting on a geometry-only basis. Here, the same geometries can be produced by both processes, but material choices are different. Compared with aluminum, zinc, or magnesium die castings, MIM components offer far superior strength, hardness, and corrosion resistance properties. In most cases, the higher properties of MIM come at a slightly higher cost when compared to die-cast components.

MIM may compete economically with stamping or the conventional powder metal process when two or more of these components are combined into a single MIM design. By reducing part-count and eliminating assem-bly hassles, a lower overall cost can be achieved. The greater design flexibility of MIM allows features like blind holes, threads, and wall thickness changes to be molded-in from the start rather than added later as 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 can begin with a clean slate, adding material in uniform wall sections only when needed. This thought process is much different than designing for machining, where reducing the amount of metal removed from a square or round stock can be an important consideration. Because MIM allows the designer to reduce material content to only what is functionally required, MIM parts are generally smaller and lighter than their machined counterparts.

The MIM designer is also freed from the restrictions imposed by the capability of the machining equip-ment. The design freedom with MIM is largely the same as with plastic injection molding. Whether the designer makes improvements by reducing mate-rial content, combining multiple components, or by molding in text and logos, the earlier Phillips-Medisize’s MIM engineers are involved, the greater the chance to experience the full benefits of metal injection molding.

Parts Appropriate for Metal Injection 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 nor-mal range is 0.25 to 0.50 degrees. In many cases, parts can be produced with no draft.

Wall ThicknessTo avoid internal stresses, voids, and sink marks, walls of uniform thickness are ideal. Thicknesses in the range of 0.050 to 0.250 inches are preferred, but exceptions in both directions are routinely done. Parts have been produced with wall sections as little as 0.005 inch and as large as 0.50 inch. Consult a Phillips-Medisize’s metal injection molding engineer for details.

Ribs and WebsRibs and webs are useful for reinforcing relatively thin walls and avoiding thick sections. They improve material flow and limit distortion, while increasing strength and rigidity of a thin wall. Rib thickness should not exceed that of the adjoining wall.

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

Design Features The design features that can be made by MIM are similar to those made by conventional plastic injection 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 considered economically practical. Phillips-Medisize has the capability to machine internal undercuts as a second-ary operation, when required.

ThreadsExternal and internal threads can be molded using MIM technology; however, secondary tapping is usual-ly more precise for internal threads. External threads are normally produced with a small flat area on the parting line of the mold to eliminate potential inter-ference from 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 orient-

ed 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 thick-

ness 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

features into a part, consideration of the loca-

tion of witnesses should be addressed with

Phillips-Medisize’s 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-Medisize can provide secondary operations to meet an array of specific requirements. Since typi-cal tolerances for the MIM process are within 0.003 to 0.005 inches per inch, (0.3-0.5%), many parts are sintered to final dimensions. If tighter tolerances are required in certain areas, secondary-machining operations can be applied. Tapping operations can produce internal threads with tolerances tighter than can be achieved via the metal injection molding process. Tumbling and polishing can provide an aes-thetic surface. Parts can be heat-treated; black oxide coated, and plated in similar fashion to investment cast or machined parts.

Secondary operations offered by Phillips-Medisize’s Metal Injection Molding include:

· 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-Medisize’s 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-Medisize to maintain tight control of

all aspects of the MIM process.Go to phillipsmedisize.com for the most up-to-date material selection chart

Phillips-Medisize’s Metal Injection Molding offers several alloys that are used in a wide variety of auto-motive, 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-Medisize metallurgist testing the strength of materials and mechanical properties

PHILLIPS-MEDISIZE

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-Medisize’s Metal Injection Molding does not warranty that these materials are fit for any particular purpose. All materials need to be tested by the customer to assure they meet minimum performance criteria.

© 2013 Phillips-Medisize

PHILLIPS-MEDISIZE

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


PHILLIPS-MEDISIZE

Nominal Chemical Composition (%) of Metal Injection Molding Alloys

Material

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)

Fe

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

17-20

Bal.

Ni

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

C

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

Others

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)

Cr

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


PHILLIPS-MEDISIZE

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)


Residual Induction

Coercive Force

Maximum Permeability

Induced Magnetic

Field

Induced Magnetic

Field

Induced Magnetic

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 design guide metal injection molding - … · metal injection molding (mim) ... requirements,...

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