This document discusses metal injection molding (MIM) for titanium components. MIM uses powdered metal and injection molding to make small, complex metal parts. The process involves feedstock formation, injection molding, de-binding, and sintering. MIM provides cost savings over machining by reducing material waste and allowing design optimization. It is well-suited for parts under 150g in annual volumes over 10,000. Considerations for MIM include part design, mold costs and timelines, secondary operations, and production requirements. Dimensions can be held to +/-0.1-0.5% with surface finishes down to 10 microns.

1. Molding
Factors & Considerations

2. Praxis Overview
Contract manufacturer of titanium components
Medical Device Manufacturing since 2008
Solely focus on titanium PM
ISO 13485 Certified | Production and Design

3. Overview
Titanium Metal Injection Molding
Technology overview
Value proposition
Cost comparison to machining
Considerations for molding
Limitations of molding
Secondary operations for MIM

4. MIM – Metal Molding Technology
Metal Injection Molding
MIM is a forming process using powdered metal, high
pressure and thermal energy to efficiently make small,
complex parts.
The design versatility of plastic injection molding with
the performance of metal

5. General MIM Process
Step 1: Feedstock Formation
• Mixture of powdered metal with binder
Step 2: Injection Molding
• Binder melts and flows into the mold carrying
metal powder which forms a green part
Step 3: De-binding
• Removal of the binder via thermal or chemical
methods
Step 4: Sintering
• A thermal process at ~70-90% of a materials
melt temperature, the component undergoes
significant shrinkage (~12-20% linear) resulting
in a density of >98%
Additional Secondary Processing: HIP, heat treating,
machining, surface finish, cleaning, passivation, laser
marking

6. Value of titanium MIM
MIM provides cost savings through better material utilization
 Reduction in part weight through design
 Reduction in raw material usage
 Typically COGS reduction of 25% minimum to initiate MIM project
Increased profitability through reduced COGS
Enhanced design flexibility
 Well suited for parts <50 g
 Combination of components
 Adding complexity may not add cost
Maintain bar stock material performance (Ti-6Al-4V)

7. MIM Candidate Requirements

8. Manufacturing method considerations
Machining Factor Molding
Simpler 3D geometry
>25% effective density
Geometry Complex 3D geometry
<25% effective density
N/A Size
<150 g (0.3 lbs)
<6” OAL
>0.02” wall thickness
< +/-0.001” Tolerances > +/-0.001” to +/-0.003”
<10k Annual Volume >10k
Note: general considerations

9. Effective density
Bar stock versus powder - Ti-6Al-4V
Powder cost is ~3x of bar stock
Powder material costs are equal to bar
stock after 73% of bar stock has been
machined away
MIM candidates have low effective
densities
Typically ~25% of the material density
Effective Density = part mass / initial volume

10. MIM Considerations
 Annual volumes
 Design Freeze
 Upfront costs and lead times
 Mold cost & lead time
 Product development cost & lead time
 Secondary operations
 Existing product: convert from machined to MIM
 New product: design for MIM

11. Mold: Timelines and Approximate Costs
Description Lead time / costs
Prototype Mold
1-6 weeks
$5k - $20k
Production Mold
6-12 weeks
$15k - $100k
 Mold life: typically 100k cycles without maintenance

12. Design Guidelines
Desirable
• Aspect ratios of 5:1 or less preferred
• Uniform wall thickness is desired, with max variation around 5X
• Wall thickness larger than 0.020 in and smaller than 0.5 in
• Minimum draft 0.5°
• Cored out features to reduce part weight
• Flat surfaces
Allowable
• Asymmetry
• Ribs and bosses
• Grooves and threads
• Decorative features (i.e. texture, logo, lettering)
Avoid
• Undercuts, no drafts
• Small diameter holes <0.050”
• Sharp corners or points
• Wall thickness <0.020”
• Large parts, parts with high aspect ratio

13. MIM Design Considerations
Gating
Location, removal, vestige
Parting line
Mismatch and flash allowances
Ejector mark
Protrusions and depression allowances
Injection molded specific issues
 Mating components
 Critical surfaces
 Functional / cosmetic
allowances

14. Dimensional Capabilities
• Dimensional precision of +/- 0.1% to +/- 0.5%
• Influenced by feature type and geometry
• Typical mass: 0.01g to 150g
• Wall thickness: from 0.5 mm (0.020 in) to 12 mm (0.5 in)
• Size range is heavily geometry dependent
• Surface finish
• Bead blast finish of ~32 µ in. Ra
• Polished finish of <10 µ in. Ra
• Minimum radius 0.07 mm (0.003 in)

15. Secondary Operations for MIM
• Potential secondary operations of MIM components:
• Machining
• Tolerances exceeding +/-0.1% will require secondary machining
• Drilling & tapping
• Polishing & grinding
• Passivation & anodizing
• Laser welding
MIM product and mold cost can be optimized based on mold
complexity, secondary operations and annual volume.

16. Value proposition
• Enhanced profitability over conventional alternatives
• Complex, small to medium sized parts
• Enhanced design flexibility
• Comparable material performance
• High volume manufacturing capability

17. Thank you
Jobe Piemme
Chief Technology Officer
Praxis Technology
jpiemme@praxisti.com
518-812-0112