QuickCast Direct Patterns for Investment Casting Tom Mueller Founder and Partner, Express Pattern Vernon Hills, IL IL
Agenda About Express Pattern An Overview of Direct Patterns The Four Primary Uses of Direct Patterns A New Resin for QuickCast Patterns Case Studies
About Express Pattern Founded in 1999 Focused on investment casting applications of rapid prototyping Currently using stereolithography and thermojet technologies Largest provider of direct patterns
SLA Capability 12 SLA Systems 1 SLA Viper Pro 3 SLA 7000 2 SLA 5000 1 SLA 500 1 SLA 350 2 SLA Viper 2 SLA 250
Viper Pro Largest SLA format 30x26x22 build envelope
Thermojet Capability 9 Thermojet Systems
New Foundry Guide Covers all aspects of using QuickCast patterns in investment casting Available at no charge to investment foundries
An Overview of Direct Patterns Definition Direct Pattern Methods Important Pattern Considerations Comparison of Leading Direct Pattern Methods
Definition Investment casting patterns made without using tooling Generally made with rapid prototyping methods Not just for prototypes Approximately 60,000 direct patterns were cast last year ~40% used for production castings
Creating Direct Patterns Scale Factor CAD Model STL File Additive Fabrication System Direct Pattern
Types of Direct Patterns Stereolithography (SLA) QuickCast Patterns Thermojet Patterns Selective Laser Sintering (SLS) Castform Patterns Solidscape Patterns Laminated Object Manufacturing (LOM) Patterns Fused Deposition Modeling (FDM) Patterns Z Corporation Patterns Machined Wax Patterns Wood Patterns
Types of Direct Patterns Stereolithography (SLA) QuickCast Patterns Thermojet Patterns Selective Laser Sintering (SLS) Castform Patterns Solidscape Patterns
SLA QuickCast Patterns
Honeycomb Internal Structure Hollow structure with hexagonal supports Allows stucture to completely drain Pattern can collapse inward as it expands with heat Less mass to burn out
QuickCast Advantages Accurate Good Surface Finish Lightweight Disadvantages Leak Possibility De-Wax Process
Thermojet Patterns
Thermojet Advantages Wax Pattern Good Surface Finish Disadvantages Accuracy Pattern Strength
SLS Castform Patterns
Castform Advantages Pattern Strength Disadvantages Accuracy Surface Finish Limitations De-Wax Process
Solidscape Patterns
Solidscape Advantages Accurate Detail Resolution Wax Pattern Disadvantages Slow
Important Pattern Considerations Build Process Considerations Accuracy Surface Finish Build Envelope Build Speed Material Considerations Ability to Assemble Pattern Strength Ease of Processing Residual Ash Heavy Metal Content
Accuracy Very little good data on RP accuracy exists Express Pattern has done the largest accuracy study ever done Based on >15,000 measurements
QuickCast and Thermojet Pattern Accuracy: Probability of a Dimension being within a Specified Tolerance Probability of a Dimension Being within a Specified Tolerance 100% 80% Probability 60% 40% 20% 0% 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.010 QuickCast Patterns 0.011 0.012 0.013 0.014 0.015 Tolerance (inches) Thermojet Patterns 0.016 0.017 0.018 0.019 0.020
Other Accuracy Conclusions Accuracy not dependent on: Dimension type Build direction
Process Comparison Chart QuickCast Thermojet CastForm Solidscape Accuracy Good Med - Poor Med Very Good Surface Finish Good Med-Good Med Good Build Envelope 25x30x22 10x7.5x8 22x22x30 6x6x12 Build Speed Medium Medium - Slow Medium Slow Pattern Strength Good Medium Very Good Medium Ease of DeWax Medium Very Good Medium Very Good Ability to Assemble Good Medium Good Good Residual Ash Good Very Good Medium Very Good Heavy Metal Content Good-Very Good Very Good Very Good Very Good
Direct Pattern Applications Prototype Castings Process Development Initial Production Castings Low Volume Production
What are Prototype Castings? Castings provided to the customer for purposes of testing and verifying the design prior to production Usually ordered prior to beginning tooling
Typical Casting Development Process Production Yes Complete Design Procure Tooling Create Casting Test OK? No Revise Tooling Revise Design
Costs of Design Changes Tooling rework costs Tooling rework time Delayed Product Introduction Restrictions on design changes
Effect of Design Changes Effect of Design Changes QuickCast Castings Time for Tool Rework Time Conventional Castings Difference in Time for Corrected Design Tooling Lead Time Design Change Number of Patterns
Benefits of Prototype Castings Verify design before investing in tooling Reduced risk of tooling rework charges Reduced risk of product delays due to tooling rework Greater design freedom in making design changes
Part 2: Direct Pattern Applications Prototype Castings Process Development Initial Production Castings Low Volume Production
How can Direct Patterns Assist in Process Development? Some steps of the casting process cannot be optimized until patterns are available Direct patterns can be used instead of waiting for molded patterns
Process Development Steps that Require Patterns Delay Delivery Possible Tool Rework Gating Trials Tree Assembly Optimization Final Shrink Determination Robotic Dip Programming Straightening Fixtures
Solution Use Direct Patterns to develop process before tooling is delivered Initial concentration on areas that could result in tooling changes
Benefits of Using Direct Patterns in Process Development Reduced risk of late delivery Reduced Risk of incurring time and cost of tooling rework
Part 2: Direct Pattern Applications Prototype Castings Process Development Initial Production Castings Low Volume Production
Initial Production Castings Use direct patterns to create initial production castings while tool is in process Allows delivery of low volumes of production castings much faster than would be possible with molded patterns Ramp up to normal production delivery when tool is delivered
Time to Deliver Castings Time to Deliver Castings Molded Wax Pattern Castings Delivery Time Time QuickCast Castings Tooling Lead Time Number of Castings Castings shipped before tooling delivered
Benefits of Using Direct Patterns for Initial Production Castings available much earlier than possible with molded patterns alone Possible to catch design problems
Direct Pattern Applications Prototype Castings Process Development Initial Production Castings Low Volume Production
Low Volume Production Castings Using Direct Patterns instead of molded wax patterns for low volume production runs.
Total Cost of Castings Total Cost of Castings QuickCast Castings Conventional Castings Machined Parts Total Cost of Parts New Business Direct Instead of Molded Conventional Casting Cost of Tooling Cost Break-Even Qty. Number of Parts QuickCast Cheaper Wax Cheaper
Time to Deliver Castings Time to Deliver Castings Conventional Castings Delivery Time Time QuickCast Castings Tooling Lead Time Time Break-Even Qty. Number of Castings QuickCast Faster Wax Faster
Effect of Design Changes Effect of Design Changes Cost of Tool Changes Conventional Castings Total Cost of Castings New Cost Break Even Quantity QuickCast Castings Cost of Tooling Design Change Cost Break-Even Qty. Number of Castings
Effect of Design Changes Effect of Design Changes QuickCast Castings Time for Tool Rework Time Conventional Castings Difference in Time for Corrected Design New Time Break Even Quantity Design Change Time Break-Even Qty. Number of Patterns
Benefits For low volumes, direct patterns can save both time and money compared to molded wax patterns and machining Very low penalty for design changes
New SLA Resin for Investment Casting Primary resin for QuickCast patterns has been WaterShed 11120 from DSM Somos Last year, DSM introduced ProtoCast AF 19120 Express Pattern beta tested and evaluated
Residual Ash Ash remaining after burnout as a percentage of the original pattern weight Can cause problems with the casting Surface pitting Inclusions Usually must be cleaned out of the shell
Residual Ash Testing Measured at two combustion temperatures 1500ºF below cristobalite conversion temp 1800ºF above cristobalite conversion temp Measured at 6 burn times 30,60,90,120,150 and 180 minutes
Residual Ash at 1500F Combustion Ash Content at 816 C (1500 F) 3.500 Ash Content (%) 3.000 2.500 2.000 1.500 1.000 ProtoCast WaterShed 0.500 0.000 30 60 90 120 150 180 Ashing Time (minute)
Residual Ash at 1500ºF Combustion Percent 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 0.093% 0.013% 11120 19120
Residual Ash at 1800F Combustion 3.000 Ash Content at 982 C (1800 F) 2.500 ProtoCast WaterShed Ash Content (%) 2.000 1.500 1.000 0.500 0.000 30 60 90 120 150 180 Ashing Time (minute)
Residual Ash at 1800ºF Combustion 0.09 Percent 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 0.089% 0.015% 11120 19120
Foundry Test Two Assemblies One assembly with 4 nine-wall parts built with WaterShed resin One assembly with 4 nine-wall parts built with ProtoCast AF resin Shells built at the same time Fired at the same time in the same furnace
Foundry Test
Foundry Results 11120 WaterShed 19120 ProtoCast AF
Results Ranked by Importance Resid. Ash 1500ºF Resid. Ash 1800ºF DSM Somos 11120 Watershed 0.093% 0.089% DSM Somos 19120 ProtoCast AF.013% 0.015% 86% Reduction! 83% Reduction!
Results Ranked by Importance Resid. Ash 1500ºF Resid. Ash 1800ºF DSM Somos 11120 Watershed 0.093% 0.089% DSM Somos 19120 ProtoCast AF.013% 0.015% Antimony Free? No Yes 86% Reduction! 83% Reduction! 100% Reduction!
Thermal Expansion Why is it important? Thermal expansion is the cause of cracking in the autoclave
Coefficient of Thermal Expansion CTE 200 180 160 140 120 100 80 60 40 20 0 185-189 131-151 11120 19120
9 Wall Test Part 11120 Casting 19120 Casting
Results Ranked by Importance Resid. Ash 1500ºF Resid. Ash 1800ºF CTE µmm/mm-ºc DSM Somos 11120 Watershed 0.093% 0.089% 185-189 DSM Somos 19120 ProtoCast AF.013% 0.015% Antimony Free? No Yes 130.5-150.9 86% Reduction! 83% Reduction! 100% Reduction! 19-31% Reduction!
Case Studies Spacecraft Electronics Housing Deep See Diving Helmet Control Handle Aircraft Gimbal Camera Mount Automotive Bracket Fighter Air Inlet Scoop for Electronics Cooling Exhaust Manifold
Messenger Space Exploration Vehicle Multiyear mission to Mercury Launched March 2004 Venus Fly-bys June 2004 and March 2006 Mercury orbit April 2009
Messenger Electronics Housing Casting by NuCast, Londerry,, NH QuickCast pattern Aluminum 356 Only minor machining required
Messenger Electronics Housing
Kirby Morgan Dive Helmet Stainless Steel Deep Sea Dive Helmet Cast by AristoCast, Almont, MI QuickCast Pattern Won AFS Best in Class Casting Award 2006
Dive Helmet Pattern
Pouring the Helmet
Cooling and Cleanup
Finished Casting
Assembled Helmet
Control Handle Aircraft control handle Cast by UniCast, Londonderry, NH Prototype and initial production castings delivered using QuickCast patterns
Aircraft Camera Gimbal Mount Gimbal Mount for Reconnaissance Camera Nu-Cast, Londonderry, NH
Aircraft Camera Gimbal Mount Foundry Material Dimensions Weight Lead Time Nu-Cast Londonderry, NH Aluminum 14 x14 x14 17 pounds 3 Weeks Tool Cost $85,000 Tool Lead Time Cost Break Even Time Break Even 14-16 Weeks 32 Castings 87 Castings
Automotive Casting Foundry Material Dimensions Weight Aristocast Almont, MI, USA Aluminum 9.5 x16 x6.5 4 pounds Tool Cost $37,000 Tool Lead Time Cost Break Even Time Break Even 6-8 Weeks 40 Castings 111 Castings
Fighter Air Inlet Scoop Inlet Scoop to provide air to cool electronics Uni-Cast, Londonderry, NH Provided initial castings 3 months prior to delivery of production tooling Winner of 2005 ICI Casting Award
Rapid Prototype Wax Patterns
Rapid Prototype Cast Parts
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