A Brief Overview of the Plaster Mold Process

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A Brief Overview of the Plaster Mold Process

• ULTRACAST, LLC

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SEPARATE COPE AND DRAG PATTERNS
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SEPARATE COPE AND DRAG PATTERNS
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SMOOTH HIGH DEFINITION MOLDS RESULT FROM THE
PLASTER METHOD
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SMOOTH HIGH DEFINITION MOLDS RESULT FROM THE
PLASTER METHOD
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ALL TRACES OF MOISTURE ARE REMOVED DURING THE
BAKING PROCESS
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ALL TRACES OF MOISTURE ARE REMOVED DURING THE
BAKING PROCESS
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METAL IS POURED BY OUR CUSTOM VACUUM PROCESS
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METAL IS POURED BY OUR CUSTOM VACUUM PROCESS
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PARTS ARE CAREFULLY BROKEN OUT OF THE MOLD BY
HAND AND POWER WASHED AT HIGH PRESSURE
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PARTS ARE CAREFULLY BROKEN OUT OF THE MOLD BY
HAND AND POWER WASHED AT HIGH PRESSURE
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THE RESULTANT CASTING SHOWN AFTER MACHINING
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THE RESULTANT CASTING SHOWN AFTER MACHINING
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TYPICAL USES OF PLASTER MOLD CASTING
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TYPICAL USES OF PLASTER MOLD CASTING

• TO REDUCE MACHINING ON HIGHLY DETAILED PARTS.
• TO REPLICATE DIE CASTINGS VERY QUICKLY
  (RAPID PROTOTYPING).
• TO REPLACE EXPENSIVE MACHINED AND DIP BRAZED
  ASSEMBLIES OR ELECTROFORMED COMPONENTS.
• TO GET PRODUCTION QUALITY PARTS IN THE PIPELINE
  BEFORE HARD TOOLING IS AVAILABLE.
• TO ACHIEVE CASTING CHARACTERISTICS NOT POSSIBLE
  BY OTHER MEANS - ie THIN WALLS, SPECIAL
  SURFACES, DIFFICULT INTERNAL SHAPES.

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TOOLING METHODS SOFT OR HARD ???

• SOFT TOOLS HARD TOOLS
• ARE LOWEST IN COST ARE MORE EXPENSIVE TO PRODUCE
• ARE QUICKEST TO PRODUCE TAKE LONGER TO PRODUCE
• HAVE SHORTER LIFESPAN OFTEN TIMES MORE ACCURATE
• ARE USED FOR PROTOTYPES OFTEN ALLOW FOR LOWER
  PIECE PRICE
• SOFT TOOLS ARE USUALLY MADE BY MOLDING URETHANE
  PLASTICS FROM MASTER MODELS THAT ARE EITHER
  MACHINED OR PRODUCED FROM AN SLA. HARD TOOLS ARE
  MADE BY DIRECT CNC MACHINING INTO METALS OR HARD
  PLASTIC.

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MOLDING AND CASTING

• PROCESS IS SIMILAR TO SAND CASTING.
• FINER FINISH, TOLERANCES AND ACCURACY THAN SAND.
• CYCLE TIME IS SLOW ( 8-12 CYCLES/DAY).
• SIZES RANGE FROM LESS THAN 1 TO GREATER THAN 3
  FT.
• ALL COMMON ALLOYS CAN BE CAST.
• VACUUM PROCESS PRODUCES SHARP DETAIL.
• ALLOY SELECTION
• A-356 HAS EXCELLENT CASTABILITY, HIGHEST
  STRENGTH IN T-6 FORM, MOST COMMON ALLOY.
• A-712 MOST DIFFICULT TO CAST, GOOD AS DIP BRAZE,
  STABLE, AND ANODIZS VERY WELL.

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DESIGN AND COST CONSIDERATIONS

• LOWEST COST / BEST CASTABILITY
• UNIFORM WALL THICKNESS. DRAFT ON ALL
  SURFACES. FILLETS AND RADII.
• RAISED PADS AND BOSSES FOR MACHINING. PARTING
  LINES RAISED FOR FINISHING.
• HIGHEST COST / GREATEST DIFFICULT
• DRASTIC SECTION CHANGES. ALL SHARP CORNERS.
  DIFFICULT CONTOUR FINISHING.
• NO DRAFT. LINE TO LINE MACHINING. EXOTIC
  DESIGN DETAILS.
• COMMON MICROWAVE COMPROMISE
• DRAFT ON THE EXTERIOR OUTSIDE CONFIGURED TO
  AID FINISHING AND MACHINING.
• FILLETS AND RADII ON THE EXTERIOR . SHARP /
  NEAR SHARP CORNERS ON INTERIOR.
• MOSTLY SQUARE INTERIOR FEATURES WITH LIMITED
  SHORT DIMENSION DRAFT ON SELECT FEATURES.

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ULTRACAST, LLC