Process Details and Selection

Process Details

Die Casting

Molten metal is injected into steel (typical H13,8407,dievar mold steel) dies under pressure. The metal solidifies, the die is opened and the part ejected.

 

High volume, near net shape, minimal machining required, excellent casting detail, smooth finish.

 

ProcessMetalsLinear ToleranceSurface Finish (RMS)Minimum Section ThicknessTypical Tooling Cost
DIE CASTINGAluminum, Zinc and MagnesiumStandard +/- .010″ to 1″ then add +/- .001″ / inch per NADCA publication #40232-63 (Zinc); 63-250 (Aluminum).030″(Mg) to .060″ (Aluminum)$10,000 to $300,000

Permanent Mold

Molten metal is gravity poured in steel (typical H13 mold steel) molds. Sand cores can be used to form internal features. The mold is opened and the casting removed.

 

All volume, able to cast internal features using cores, lower cost tooling.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
Aluminum and ZincStandard +/- .015″ to 1″ then add +/- .002″ / inch150 -300.188″$10000 to $100000

Low Pressure Casting

In low-pressure casting, the furnace is pressurized whereby the molten aluminum is brought into the casting die through the riser tube. The die is filled by slowly climbing, controlled, and above all, constant pressure. The laminar filling process avoids the formation of oxidation, the onset of cold currents and the danger of air inclusions.

 

All volume, able to cast internal features using cores, compressed structure,tensile strength and hardness is better than gravity casting, compression resistance and leak-proof.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
AluminumStandard +/- .015″ to 1″ then add +/- .002″ / inch150 -300.188″$10000 to $300000

Sand Castings

Treated sand is packed around a wood or metal pattern. Cores are added to form internal features. Molten metal is poured into sand molds. Molds are broken to remove the castings.

 

All volumes,able to cast complex internal passageways, low tooling cost, short tooling lead time.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
All MetalsStandard +/- .030″ up to 6″, Add +/- .002″ for every inch over 6500-2000.150″$2000 to $40000

Modified Shell Molding

A heated steel (typical H13 mold steel)pattern is placed over a ductile iron mold. A thin layer of shell sand is injected into the gap between pattern and ductile iron mold. The thin layer shell sand solidifies onto ductile iron mold after cooling.Mold closed and molten metal poured. Sand cores can be used to form internal features. Mold is opened, casting is removed, and ductile iron mold is cleaned before next use.

 

Medium to high volumes, high yield rates, smoother casting surface, porosity free and closer tolerances than sand castings.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
Gray and Ductile IronISO 8062-3 DCTG Grade 8-12 Or Standard +/- .020″ up to 6″, Add +/- .002″ for every inch over 6500-1000.12″$10000 to $50000

Lost Foam

A metal mold is used to produce polystyrene foam patterns. Foam patterns are coated with a ceramic coating. Foam patterns are packed in loose sand. Molten metal is poured on to foam patterns. The foam pattern evaporates and is replaced by the metal.

 

Offers design flexibility. Complex shapes can be made when multiple patterns are glued together. No draft required.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
Aluminum and IronStandard +/-.010″ for 1 to 3″ then add +/-.003″ / inch250-1000.150″$10000 to $100000

Squeeze Casting (Liquid Forging)

Squeeze casting is a combination of casting and forging processes. An exact amount of molten meal is gravity poured into a die. Pressure is applied until the part solidifies. Cores can be used to create internal features.

 

Medium to high volume. Low levels of porosity. More internal features can be cast using cores than die casting.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
AluminumStandard +/- .010″ to 1″ then add +/- .001″ / inch perNADCA publication #40290-500.30″$10000 to $300000

Investment Casting (Lost Wax)

A metal mold is used to produce wax patterns. Wax patterns are attached to a pouring tree. Trees are dipped in slurry to form outer shell. Wax is evacuated and metal is poured into cavity. Shell is broken and castings removed.

 

All volumes, near net shape, minimal machining, excellent surface finish, more design freedom.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
Aluminum and SteelStandard +/- .005″ to 3″ then add +/- .003″ / inch63-250.060″$3500 to $25000

Metal Injection Molding (MIM)

Metal Injection Molding (MIM) is a metal working process that draws on two technologies — plastic injection molding and powdered metallurgy. Finely powdered metal (typically less than 20 micrometers) is mixed with a binder material to create a feedstock that is then fed into the cavities of a regular injection molding machine.

 

MIM allows for more design complexity – for example, thinner wall sections, sharper cutting points and tighter tolerances of up to +0.005″ per linear inch – as compared to the investment casting process. In addition, MIM is better suited for the production of smaller parts that weight less than 20 grams, and that are less than 100 mm long.
METALSLINEAR TOLERANCESURFACE FINISH (RMS)MINIMUM SECTION THICKNESSTYPICAL TOOLING COST
Stainless and Carbon SteelsStandard +/- .005″ to 1″ then add +/- .002″ / inch40-252.02″$8000 to $15000

Process Comparison Table

ProcessMetalsLinear ToleranceSurface Finish (RMS)Minimum Section ThicknessTypical Tooling Cost
DIE CASTINGAluminum, Zinc and MagnesiumStandard +/- .010″ to 1″ then add +/- .001″ / inch per NADCA publication #40232-63 (Zinc); 63-250 (Aluminum).030″(Mg) to .060″ (Aluminum)$10,000 to $300,000
PERMANENT MOLDAluminum and ZincStandard +/- .015″ to 1″ then add +/- .002″ / inch150-300.188″$10,000 to $100,000
LOW PRESSURE CASTINGAluminumStandard +/- .015″ to 1″ then add +/- .002″ / inch150-300.188″$10,000 to $300,000
SAND CASTINGSAll MetalsStandard +/- .030″ up to 6″, Add +/- .002″ for every inch over 6500-2000.150″$2,000 to $40,000
LOST FOAMAluminum and IronStandard +/-.010″ for 1 to 3″ then add +/-.003″ / inch250-1000.150″$10,000 to $100,000
INVESTMENT CASTING (LOST WAX)Aluminum and SteelStandard +/- .005″ to 3″ then add +/- .003″ / inch63-250.060″$3,500 to $25,000
MODIFIED SHELL MOLDINGGray and Ductile IronISO 8062-3 DCTG Grade 8-12 Or Standard +/- .020″ up to 6″, Add +/- .002″ for every inch over 6500-1000.12″$10,000 to $50,000
SQUEEZE CASTING (LIQUID FORGING)AluminumStandard +/- .010″ to 1″ then add +/- .001″ / inch per NADCA publication #40290-500.30″$10,000 to $300,000
Metal Injection Molding (MIM)Stainless and Carbon SteelsStandard +/- .005″ to 1″ then add +/- .002″ / inch40-252.02″$8,000 to $15,000