Machined vs. Molded

Smart and Innovative Machining

Ken Gredick | Engineering Manager | June 16, 2016

EDM Turning

When Do I Choose Machining? Tight Tolerance • Complex Geometry • Repeatable Process • Surface Finishes

Metal Sintering Injection Molding

Grinding EDM Milling Turning

The Challenging Way

Machining

The Original Design

The Original Process Flow Machining initial quantity of 50 parts

OP 10: Saw

OP: 20/30- Turning

Turned Blank

OP 40: Milling

Milled Pocket

OP 50: Heat Treating

OP 60: Grinding

OP 70: Wire EDM

Finish Small Square

Collaboration

Leads to…

Designer Buyer Manufacturer

Design for Manufacturing (DFM) Leads to an Updated Print

Updated Process Flow

From

To

Lot Size 50 Part Price: $178.00

Total: $8,900.00

Lot Size 1,000 Part Price: $60.00 Total: $60,000.00

Lot Size 1,000 Part Price: $37.40 Total: $37,400.00

Cost of Original Design

“DFM”

Cost of New Design

Lot Size 50 Part Price: $116.00 Total: $5,800.00

Savings

Lot Size 50 Total Savings: $3,100.00

Lot Size 1,000 Total Savings: $22,600.00

Smart and Innovative Machining

Designer: Reduced

Lead Time

Buyer: Reduced

Cost

Machining for: • Complex Geometry

• Tight Tolerance • Surface Finish

• Repeatable

Manufacturer: Streamlined

Process

Molding Factors & Considerations

Praxis Overview

Contract manufacturer of titanium components Medical Device Manufacturing since 2008

Solely focus on titanium PM ISO 13485 Certified | Production and Design

Overview

Titanium Metal Injection Molding

Technology overview Value proposition Cost comparison to machining Considerations for molding Limitations of molding Secondary operations for MIM

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

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

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)

MIM Candidate Requirements

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

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

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

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

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

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

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)

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.

Value proposition

• Enhanced profitability over conventional alternatives • Complex, small to medium sized parts

• Enhanced design flexibility • Comparable material performance • High volume manufacturing capability

Thank you

Jobe Piemme

Chief Technology Officer

Praxis Technology

jpiemme@praxisti.com

518-812-0112