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How good are SLA QuickCast patterns for investment casting?
QuickCast Direct Patterns for Investment Casting Tom Tom Mueller Mueller Founder Founder and and Partner, Partner, Express Express Pattern Pattern Vernon Vernon Hills, 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% 60% 40% 20% 0% 0. 00 1 0. 00 2 0. 00 3 0. 00 4 0. 00 5 0. 00 6 0. 00 7 0. 00 8 0. 00 9 0. 01 0 0. 01 1 0. 01 2 0. 01 3 0. 01 4 0. 01 5 0. 01 6 0. 01 7 0. 01 8 0. 01 9 0. 02 0 Probability 80% Tolerance (inches) QuickCast Patterns Thermojet Patterns 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 Design Change Ca st ing s Qu ick Ca st Time for Tool Rework Difference in Time for Corrected Design Tooling Lead Time Time Effect of Design Changes Conventional Castings 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 Gating Trials Tree Assembly Optimization Final Shrink Determination Robotic Dip Programming Straightening Fixtures Possible Tool Rework 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 Ca st ing s tings ttern Cas a P x a W Molded Qu ick Ca st Tooling Lead Time Delivery Time Time Time to Deliver Castings 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. Cost of Tooling M ac hi ne d Pa rt s Total Cost of Parts Total Cost of Castings New Business Q Direct Instead of Molded Cost Break-Even Qty. QuickCast Cheaper s Ca k c ui gs tin s a tC tings onal Cas ti n e v n o C Conventional Casting Number of Parts Wax Cheaper Ca st ing s s Conventional Casting Qu ick Ca st Tooling Lead Time Delivery Time Time Time to Deliver Castings Time Break-Even Qty. QuickCast Faster Number of Castings Wax Faster Cost of Tooling Total Cost of Castings Effect of Design Changes Cost of Tool Changes tings onal Cas Conventi s Ca t s Ca ck i Qu New Cost Break Even Quantity gs tin Design Change Cost Break-Even Qty. Number of Castings Ca st ing s Qu ick Ca st Time for Tool Rework Conventional Castings Difference in Time for Corrected Design Time Effect of Design Changes 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 ProtoCast 3.000 Ash Content (%) WaterShed 2.500 2.000 1.500 1.000 0.500 0.000 30 60 90 120 Ashing Time (minute) 150 180 Residual Ash at 1500ºF Combustion 0.1 Percent 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 Ash Content at 982°C (1800°F) 3.000 ProtoCast Ash Content (%) 2.500 WaterShed 2.000 1.500 1.000 0.500 0.000 30 60 90 120 Ashing Time (minute) 150 180 Residual Ash at 1800ºF Combustion 0.09 0.08 0.07 0.089% Percent 0.06 0.05 0.04 0.03 0.02 0.01 0 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 DSM Somos DSM Somos 11120 19120 Watershed ProtoCast AF Resid. Ash 1500ºF 0.093% .013% 86% Reduction! Resid. Ash 1800ºF 0.089% 0.015% 83% Reduction! Results Ranked by Importance DSM Somos DSM Somos 11120 19120 Watershed ProtoCast AF Resid. Ash 1500ºF 0.093% .013% 86% Reduction! Resid. Ash 1800ºF 0.089% 0.015% 83% Reduction! Antimony Free? No Yes 100% Reduction! Thermal Expansion Why is it important? – Thermal expansion is the cause of cracking in the autoclave Coefficient of Thermal Expansion 200 CTE 180 160 140 185189 120 100 131151 80 60 40 20 0 11120 19120 9 Wall Test Part 11120 Casting 19120 Casting Results Ranked by Importance DSM Somos DSM Somos 11120 19120 Watershed ProtoCast AF Resid. Ash 1500ºF 0.093% .013% 86% Reduction! Resid. Ash 1800ºF 0.089% 0.015% 83% Reduction! Antimony Free? No Yes 100% Reduction! CTE µmm/mm-ºC 185-189 130.5-150.9 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 Nu-Cast Londonderry, NH Material Aluminum Dimensions 14”x14”x14” Weight 17 pounds Lead Time 3 Weeks Tool Cost $85,000 Tool Lead Time 14-16 Weeks Cost Break Even 32 Castings Time Break Even 87 Castings Automotive Casting Foundry Aristocast Almont, MI, USA Material Aluminum Dimensions 9.5”x16”x6.5” Weight 4 pounds Tool Cost $37,000 Tool Lead Time 6-8 Weeks Cost Break Even 40 Castings Time Break Even 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 Thank You
