omtec 2016 molding considerations - praxis technology
TRANSCRIPT
Molding Factors & Considerations
Praxis OverviewContract manufacturer of titanium componentsMedical Device Manufacturing since 2008Solely focus on titanium PM ISO 13485 Certified | Production and Design
Overview
Titanium Metal Injection Molding
Technology overviewValue propositionCost comparison to machiningConsiderations for moldingLimitations of moldingSecondary 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 ProcessStep 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 MIMMIM 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-4VPowder 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 Mold1-6 weeks
$5k - $20k
Production Mold6-12 weeks
$15k - $100k
Mold life: typically 100k cycles without maintenance
Design GuidelinesDesirable• 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
GatingLocation, removal, vestige
Parting lineMismatch and flash allowances
Ejector markProtrusions 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
