Articles

DESIGN VARIABLES FOR THE CASTING PROCESSES

Process

Variable

Green SandDry Sand
(Chemical or Vapor Cure)
Permanent Mold
(Gravity Die Casting)
Rubber Plaster Mold
(RPM)
Die CastingInvestment
(Lost Wax)
Metals CastWide range of ferrous and non-ferrous alloys Wide range of ferrous and non-ferrous alloys Nonferrous alloys (Al, Zn, Mg, certain Cu), some Fe Al and Zn alloys only Nonferrous alloys only (Al, Zn, Cu, Mg, Sn, Pb) Nearly all ferrous and non-ferrous alloys
Complexity of Shape 33241 (Least)4 (Greatest)
Casting WeightOunces to TonsOunces to TonsOunces to 250 lbs.Ounces to 75 lbs.Ounces to 40 lbs.Ounces to 250 lbs.
Min. Section Thickness0.125"-0.250"0.060"-0.250"0.060"-0.250"0.040"-0.080"0.025"-0.080"0.020"-0.080"
Linear Dimensional Tolerances+/-0.015-0.250 in.

Add +/- 0.015"-0.250" across parting plane
+/-0.020-0.060 in.

Add +/- 0.020"-0.060" across parting plane
Under 1":
+/-0.010"

Over 1" add
+/-0.002 in/in

Add +/-0.015-0.060" across parting plane
+/-0.010" to 8 in
Add+/-0.001 in/in above 8 in

Add +0.005"/-0.000" across parting plane
+/-0.0015-0.005 in

Add +/-0.001"-0.005" across parting plane
Under 1": +/-0.010"

Over 1" add
+/-0.003 in/in
Surface Finish
(Micro Inches)
150-500150-250150-35032-6332-6363-125
Tooling CostsLowLowModerateLow-to-ModerateHighLow-to-Moderate
Optimum Lot SizeSmall-to-large depending on degree of process mechanizationSmall-to-medium depending on degree of process mechanizationMediumSmall-to-MediumLargeSmall-to-Medium depending on degree of process mechanization
Draft Required1-5 degrees1-3 degrees2-5 degrees0-2 degrees1/2 to 2 degreesNone
AdvantagesHigh production rates possible through mechanizationMoisture-free moldMold life from 15,000 to 100,000 cycles or more depending upon pouring temperature of metal and upon casting specs.

Both metal and sand cores are used.
Near net shape castings require minimal machining

Common bridge to production parts for die casting
Mold life from 15,000 to over 100,000 cycles depending upon pouring temperature of metal and upon casting specs.

Near-net-shape castings require minimal machining
No Parting Plane.

Accommodates nearly all metals.

Near-net-shape castings require minimal machining
DisadvantagesMold is not reusable.Mold is not reusable.Some shapes cannot be cast.Limited metal alloy choices

Mold is not reusable
Sealing may be required to achieve leak tight castings.

Metal cores only. Sand cores cannot be used.

Some shapes cannot be cast.
Mold is not reusable. Mold materials not reusable.

Process is labor and energy intensive.
PLEASE NOTE:

Data in the table was compiled from multiple sources, including casting process handbooks, engineering handbooks, and numerous foundries. The data is typical for the metal casting industry, but not specific to any one foundry.

Ranges are shown for the process variables in order to accommodate varying metal types, geometry & size of the casting, degree of process mechanization, and because some of the variables are interdependent.

Process capability is also a function of foundry capability, in terms of available technology, equipment, and expertise.

Some foundries can routinely produce castings outside of the above ranges depending on their degree of specialization and/or process control.

Information in the above table is for reference use only. Please contact POTTERFIELD & ASSOCIATES for design data applicable to a specific foundry, casting process, or custom casting application.

Please Contact Us with questions, or for more specific, detailed information.



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