LOST FOAM PROTOTYPING METHODS A Comparison of Methods and Processes Copyright 2002 Austin Group, LLC. All rights reserved.
INTRODUCTION TERRY AUSTIN PRESIDENT AUSTIN GROUP, LLC QUINCY, ILLINOIS
INTRODUCTION CONSULTING TO THE LOST FOAM INDUSTRY SINCE 1987 AREAS OF CONCENTRATION Design of castings Design and manufacture of prototypes Design and construction of Lost Foam tooling Process Documentation
INTRODUCTION DIVERSE LOST FOAM MARKET AREA EXPERIENCE Industrial products pumps, valves Electric motors stator housings Heavy equipment hydraulic motors, truck suspension parts Automotive engine heads, crankshafts, transmission parts
THE LOST FOAM CASTING PROCESS
THE LOST FOAM CASTING PROCESS PROCESS STEPS 1. Mold foam pattern sections. 2. Age pattern to allow dimensional shrinkage. 3. Assemble pattern if it is a multiple piece pattern. 4. Build cluster(multiple patterns per cluster). 5. Coat cluster. 6. Dry coating. 7. Compact cluster in flask. 8. Pour metal. 9. Extract cluster from flask.
THE LOST FOAM CASTING PROCESS 1. MOLD FOAM PATTERN SECTIONS
THE LOST FOAM CASTING PROCESS 2. AGE PATTERN Foam pattern is allowed to cure for a specified period of time, typically 5 to 7 days. This allows moisture to evaporate from the pattern. Patterns can also be force aged by curing in a drying oven.
THE LOST FOAM CASTING PROCESS 3. ASSEMBLE THE PATTERN
THE LOST FOAM CASTING PROCESS 4. CLUSTERING Glue individual patterns to sprue. Number of patterns per sprue is dependent on part size and/or configuration. Molded sprue is manufactured similar to foam pattern
THE LOST FOAM CASTING PROCESS 5. COATING Coating parameters verified before coating cluster. Coating is mixed continuously to maintain properties.
THE LOST FOAM CASTING PROCESS 6. DRYING Coating is dried in an oven at 120-140 F(49-60 C) for 3 to 5 hours. Small passages may increase drying time required.
THE LOST FOAM CASTING PROCESS 7. CLUSTER COMPACTION Cluster is delivered to the pouring line by conveyor. Cluster is placed into flask and held in position by a fixture Fixture is timed to release the cluster during the compaction cycle.
THE LOST FOAM CASTING PROCESS 7. CLUSTER COMPACTION (Cont.) Sand is rained into flask from overhead bin. Sand is compacted from approximately 90-95 lb/ft³ to 108 lb/ft³ by compaction table. Compaction tables are either vertical or horizontal. The compaction cycle is controlled by a PLC (magnitude and timing).
THE LOST FOAM CASTING PROCESS 8. METAL POUR Metal is poured to displace the polystyrene pattern.
THE LOST FOAM CASTING PROCESS 9. EXTRACTION Bottom drain sand away from cluster to prevent casting damage. Remove cluster from flask with hoist.
THE LOST FOAM CASTING PROCESS FINAL CASTING
PROTOTYPE METHODS
PROTOTYPE METHODS REASONS TO DEVELOP Shorter Lead Times Improve Casting Design Test Casting and Foundry Processes Field Testing of Parts
PROTOTYPE METHODS OBJECTIVES Improve dimensional accuracy Incorporate production pattern design and valueadded features Improve durability of the prototype Minimize pattern and casting delivery times
PROTOTYPE METHODS TWO MAJOR METHODS Fabricated Foam CNC Machined Aluminum Prototype Tooling
FABRICATED FOAM
FABRICATED FOAM ADVANTAGES Short lead times (typically 2 to 3 weeks to produce a ready-to-cast pattern) Produces a dimensionally accurate pattern Use original customer 3D data Replicates production parting and glue lines Foundry can cast prototype pattern using standard casting methods
FABRICATED FOAM DESIGN PROCESS OBJECTIVES Use customer 3D data as base model Add Lost Foam process features to model Add draft, radii and fillets Add shrink factors Determine parting and glue lines
FABRICATED FOAM DETERMINE PARTING AND GLUE LINES
FABRICATED FOAM DESIGN PROCESS STEPS Generate solid model Produce models for pattern fabrication
FABRICATED FOAM GENERATE THE SOLID MODEL
FABRICATED FOAM MACHINING PROCESS STEPS Translate CAD model to CNC station Construct fixtures Choose foundry grade foam material Directly machine foam material using tool paths and CNC station
FABRICATED FOAM MACHINING THE FOAM
FABRICATED FOAM PROCESS ISSUES Surface finish Foam material Value-Added Features Casting defects
FABRICATED FOAM SURFACE FINISH Surface finish can be controlled Economy, standard and fine levels Combination of cutting speeds and tool path techniques and surface preparation Initial expected finish similar to sand casting Recent finish results near molded foam quality
FABRICATED FOAM SURFACE FINISH
FABRICATED FOAM SELECTING THE MATERIAL Foundry grade material equal to production Test material for qualities Avoid construction grades
FABRICATED FOAM VALUE-ADDED ADDED FEATURES Cast-in bolt holes Decreased machining with as-cast surfaces Zero draft areas
FABRICATED FOAM VALUE-ADDED ADDED FEATURES
FABRICATED FOAM CASTING THE PATTERN Use normal Lost Foam casting process steps (gluing, coating, drying, etc.) Gating and assembly can be included in pattern or designed in the foundry Casting pouring techniques must be targeted due to small number of parts being produced
FABRICATED FOAM EXAMPLES
FABRICATED FOAM EXAMPLES
FABRICATED FOAM EXAMPLES
NEW INNOVATIONS IN LOST FOAM Prototype Project Case Study Using Fabricated Foam
ORIGINAL CUSTOMER DRAWINGS Axle housing drawings as received from Thumper Pro.
DEVELOPING THE 3D MODEL Drawing main body, revolved surface Adding Brake Mount
DEVELOPING THE 3D MODEL Adding Support Fins to Body Adding Radii to Solid Body
FINAL MODELS Assembled Right & Left Casting Models
FABRICATED FOAM PROCESS STEPS After initial 3D design of the part was completed, Lost Foam prototype patterns were produced. The major steps to produce these Fabricated Foam patterns include: Split models to allow for external and internal cutting. Make fixtures to hold model pieces during cutting operations Cut model pieces from foundry grade foam material Glue and assemble various foam pattern pieces
FABRICATED FOAM PIECES Complete pattern required six foam pieces to be produced and assembled
SECOND PIECE ASSEMBLY
THIRD PIECE ASSEMBLY
FOURTH & FIFTH PIECE ASSEMBLY
SIXTH PIECE ASSEMBLY
FULLY ASSEMBLED PATTERN
FULLY ASSEMBLED PATTERN
LOST FOAM CASTING PROCESS FINISHED CASTING
LOST FOAM CASTING PROCESS FINAL CASTING Final casting has excellent properties for machining, painting and finishing operations
THUMPER PRO AXLE HOUSING TIME LINE 3D Design Tool Path Foam Cast 12/14/01 12/20/01 12/22/01 1/7/02 1/10/02 1/14/02 DESIGN TO CASTING: 4 WEEKS
MACHINED ALUMINUM PROTOTYPE TOOLING
MACHINED ALUMINUM PROTOTYPE TOOLING ADVANTAGES Allows shorter lead time than production tooling (typically 4 to 6 weeks to build and assemble) Cost savings methods decrease initial tooling investment Molded prototype pattern can be made identical to production pattern Allows foundry to mirror production casting methods Prototype tooling materials are durable enough to run thousands of parts
MACHINED ALUMINUM PROTOTYPE TOOLING DESIGN PROCESS Uses customer 3D data as base model Add Lost Foam process features Design base tool components
MACHINED ALUMINUM PROTOTYPE TOOLING DESIGN PROCESS
MACHINED ALUMINUM PROTOTYPE TOOLING DESIGN PROCESS Incorporate standard mold components Use foam molder specifications Design is produced as an integrated assembly of components Typically, molds are designed to run in standardized prototyping or production steam chests
MACHINED ALUMINUM PROTOTYPE TOOLING DESIGN PROCESS
MACHINED ALUMINUM PROTOTYPE TOOLING MACHINING AND TOOL BUILD Translate CAD models of tool components to CNC station Mold cavities are machined directly from aluminum billet stock Eliminate unnecessary machining and polishing operations Construct using standard tooling methods
MACHINED ALUMINUM PROTOTYPE TOOLING MACHINING AND TOOL BUILD
MACHINED ALUMINUM PROTOTYPE TOOLING FOAM PATTERN MOLDING Use standard Lost Foam pattern molding process steps to mold foam patterns Age patterns using normal methods
MACHINED ALUMINUM PROTOTYPE TOOLING FOAM PATTERN MOLDING
MACHINED ALUMINUM PROTOTYPE TOOLING CASTING THE PATTERN Use normal Lost Foam casting process steps (gluing, coating, drying, etc.) Gating is typically included in the prototype pattern. Patterns can be hand assembled or prototype glue fixtures can be manufactured Casting pouring techniques used for normal production jobs are used
MACHINED ALUMINUM PROTOTYPE TOOLING CASTING THE PATTERN
MACHINED ALUMINUM PROTOTYPE TOOLING SUMMARY Closely replicates production tooling methods Provides a cost-effective tooling alternative to test early design stages Capable of running thousands of parts due to durability of materials used.
PROTOTYPE PROCESS ISSUES CASTING DEFECTS Prototype castings are subject to the same type of defects that are apparent in production castings Laps or folds Leaks Carbon Inclusions Crucial to minimize defects due to small number of parts being produced Defects found in prototyping process are useful to improve the production process
PROTOTYPE PROCESS ISSUES COSTS AND COMPARISONS Understanding correct parts for process Expectations vs. results Cost comparison What is being provided?
PROTOTYPE PROCESS ISSUES COST COMPARISON SHEET FABRICATED FOAM Cost 5 Patterns 10 Patterns 20 Patterns 25 Patterns 30 Patterns CAD Model & Modifications $ 3,000 $ 3,000 $ 3,000 $ 3,000 $ 3,000 $ 3,000 Set-up CNC & Cut Time $ 600 $ 3,000 $ 6,000 $ 12,000 $ 15,000 $ 18,000 Ship Foams $ 50 $ 250 $ 500 $ 1,000 $ 1,250 $ 1,500 Delivery 2 weeks 4 weeks 6-1/2 weeks 7-1/2 weeks 9 weeks Total $ 6,250 $ 9,500 $ 16,000 $ 19,250 $ 22,500 Price Each Pattern $ 1,250 $ 950 $ 800 $ 770 $ 750 SAMPLE TOOLING Cost 5 Patterns 10 Patterns 20 Patterns 25 Patterns 30 Patterns Tool Price $ 17,275 $ 17,275 $ 17,275 $ 17,275 $ 17,275 $ 17,275 CAD Model & Modifications $ 3,000 $ 3,000 $ 3,000 $ 3,000 $ 3,000 $ 3,000 Ship Tool $ 500 $ 500 $ 500 $ 500 $ 500 $ 500 Set-up Mold $ 300 $ 300 $ 300 $ 300 $ 300 $ 300 Foam Pattern Price $ 8 $ 40 $ 80 $ 160 $ 200 $ 240 Cure & Ship Foams $ 150 $ 150 $ 150 $ 150 $ 150 $ 150 Delivery 9 Weeks 9 Weeks 9 Weeks 9 Weeks 9 Weeks Total $ 21,265 $ 21,305 $ 21,385 $ 21,425 $ 21,465 Price Each Pattern $ 4,253 $ 2,131 $ 1,069 $ 857 $ 716
PROTOTYPE PROCESS ISSUES COST COMPARISON CHART FABRICATED FOAM vs. SAMPLE TOOLING $4,500 $4,000 Fabricated Foam $3,500 Sample Tool PRICE PER PATTERN $3,000 $2,500 $2,000 $1,500 28 PATTERNS $1,000 $500 $0 5 Patterns 10 Patterns 20 Patterns 25 Patterns 30 Patterns
SUMMARY Processes have the ability to produce customer parts in a short time frame Initial capital investment is greatly reduced Prototype castings are usable as a field-test parts Design ideas are opened up by speed and accuracy of prototyping processes Rapid prototyping methods have more potential to develop