LOST FOAM PROTOTYPING METHODS

Transcription

1 LOST FOAM PROTOTYPING METHODS A Comparison of Methods and Processes Copyright 2002 Austin Group, LLC. All rights reserved.

2 INTRODUCTION TERRY AUSTIN PRESIDENT AUSTIN GROUP, LLC QUINCY, ILLINOIS

3 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

4 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

5 THE LOST FOAM CASTING PROCESS

6 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.

7 THE LOST FOAM CASTING PROCESS 1. MOLD FOAM PATTERN SECTIONS

8 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.

9 THE LOST FOAM CASTING PROCESS 3. ASSEMBLE THE PATTERN

10 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

11 THE LOST FOAM CASTING PROCESS 5. COATING Coating parameters verified before coating cluster. Coating is mixed continuously to maintain properties.

12 THE LOST FOAM CASTING PROCESS 6. DRYING Coating is dried in an oven at F(49-60 C) for 3 to 5 hours. Small passages may increase drying time required.

13 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.

14 THE LOST FOAM CASTING PROCESS 7. CLUSTER COMPACTION (Cont.) Sand is rained into flask from overhead bin. Sand is compacted from approximately 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).

15 THE LOST FOAM CASTING PROCESS 8. METAL POUR Metal is poured to displace the polystyrene pattern.

16 THE LOST FOAM CASTING PROCESS 9. EXTRACTION Bottom drain sand away from cluster to prevent casting damage. Remove cluster from flask with hoist.

17 THE LOST FOAM CASTING PROCESS FINAL CASTING

18 PROTOTYPE METHODS

19 PROTOTYPE METHODS REASONS TO DEVELOP Shorter Lead Times Improve Casting Design Test Casting and Foundry Processes Field Testing of Parts

20 PROTOTYPE METHODS OBJECTIVES Improve dimensional accuracy Incorporate production pattern design and valueadded features Improve durability of the prototype Minimize pattern and casting delivery times

21 PROTOTYPE METHODS TWO MAJOR METHODS Fabricated Foam CNC Machined Aluminum Prototype Tooling

22 FABRICATED FOAM

23 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

24 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

25 FABRICATED FOAM DETERMINE PARTING AND GLUE LINES

26 FABRICATED FOAM DESIGN PROCESS STEPS Generate solid model Produce models for pattern fabrication

27 FABRICATED FOAM GENERATE THE SOLID MODEL

28 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

29 FABRICATED FOAM MACHINING THE FOAM

30 FABRICATED FOAM PROCESS ISSUES Surface finish Foam material Value-Added Features Casting defects

31 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

32 FABRICATED FOAM SURFACE FINISH

33 FABRICATED FOAM SELECTING THE MATERIAL Foundry grade material equal to production Test material for qualities Avoid construction grades

34 FABRICATED FOAM VALUE-ADDED ADDED FEATURES Cast-in bolt holes Decreased machining with as-cast surfaces Zero draft areas

35 FABRICATED FOAM VALUE-ADDED ADDED FEATURES

36 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

37 FABRICATED FOAM EXAMPLES

38 FABRICATED FOAM EXAMPLES

39 FABRICATED FOAM EXAMPLES

40 NEW INNOVATIONS IN LOST FOAM Prototype Project Case Study Using Fabricated Foam

41 ORIGINAL CUSTOMER DRAWINGS Axle housing drawings as received from Thumper Pro.

42 DEVELOPING THE 3D MODEL Drawing main body, revolved surface Adding Brake Mount

43 DEVELOPING THE 3D MODEL Adding Support Fins to Body Adding Radii to Solid Body

44 FINAL MODELS Assembled Right & Left Casting Models

45 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

46 FABRICATED FOAM PIECES Complete pattern required six foam pieces to be produced and assembled

47 SECOND PIECE ASSEMBLY

48 THIRD PIECE ASSEMBLY

49 FOURTH & FIFTH PIECE ASSEMBLY

50 SIXTH PIECE ASSEMBLY

51 FULLY ASSEMBLED PATTERN

52 FULLY ASSEMBLED PATTERN

53 LOST FOAM CASTING PROCESS FINISHED CASTING

54 LOST FOAM CASTING PROCESS FINAL CASTING Final casting has excellent properties for machining, painting and finishing operations

55 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

56 MACHINED ALUMINUM PROTOTYPE TOOLING

57 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

58 MACHINED ALUMINUM PROTOTYPE TOOLING DESIGN PROCESS Uses customer 3D data as base model Add Lost Foam process features Design base tool components

59 MACHINED ALUMINUM PROTOTYPE TOOLING DESIGN PROCESS

60 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

61 MACHINED ALUMINUM PROTOTYPE TOOLING DESIGN PROCESS

62 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

63 MACHINED ALUMINUM PROTOTYPE TOOLING MACHINING AND TOOL BUILD

64 MACHINED ALUMINUM PROTOTYPE TOOLING FOAM PATTERN MOLDING Use standard Lost Foam pattern molding process steps to mold foam patterns Age patterns using normal methods

65 MACHINED ALUMINUM PROTOTYPE TOOLING FOAM PATTERN MOLDING

66 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

67 MACHINED ALUMINUM PROTOTYPE TOOLING CASTING THE PATTERN

68 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.

69 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

70 PROTOTYPE PROCESS ISSUES COSTS AND COMPARISONS Understanding correct parts for process Expectations vs. results Cost comparison What is being provided?

71 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

72 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, PATTERNS $1,000 $500 $0 5 Patterns 10 Patterns 20 Patterns 25 Patterns 30 Patterns

73 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