General Comparison of
Foundry Molding Processes

Foundry Process Process Advantages Alloys & Production
Green Sand Mold Moist, bonded sand is packed around a wood or metal pattern. The pattern halves removed, the mold is assembled with or without cores. Almost any metal can be used, almost no limit on size, shape or weight of part, low cost, most direct route from pattern to casting. Ferrous, non-ferrous, Low, medium, High volume
No-Bake Mold Chemically bonded sand place in mold boxes surrounding the pattern halves. At room temperature, the molds become rigid. Pattern halves are removed and the mold is assembled with or without cores. Minimum mold wall movement, better as-cast surfaces, improved dimensional repeatability, less skill and man hours required then in conventional sand molding. Ferrous, Non Ferrous. Low, Medium and High Volume
Resin Shell Mold Resin coated sand is applied to heated metal patterns forming shell-like mold halves. Pattern halves are bonded together with or without cores. Rapid production rate, good dimensional repeatability. Lightweight molds may be stored almost indefinitely. Ferrous, Non Ferrous. Medium and High Volume
Permanent Mold Mold cavities are machined into metal die blocks & designed for repetitive use. Cores made of an expendable material. The mold halves are clamped & molten metal is gravity fed to the cavity (sometimes low pressure is applied). Molds open and castings are ejected. Good surface finish and grain structure. Good dimensional accuracy. Repeated use of molds. Rapid production rate. Low scrap loss and minimal porosity. Non Ferrous. Medium and High Volume
Die Casting Molten metal is forced into closed, steel dies at high velocities indicated by the application of pressure. When the metal solidifies, the die is opened and the casting ejected. Extremely smooth surfaces, excellent dimensional accuracy and rapid production rate. Non Ferrous. Low, Medium and High Volume
Plaster Mold Slurry of special gypsum plaster mixed with water and other ingredients is poured over pattern and allowed to set. Pattern is removed and mold halves baked. High dimensional accuracy, smooth surface finishes, almost unlimited intricacy and no porosity. Primary for prototyping. Non Ferrous. Low, Medium Volume
Investment Casting Refractory slurry is cast around (or dipped on) a pattern formed from wax. When the slurry hardens, the wax pattern is melted out and the mold or ceramic shell is oven cured. High dimensional accuracy, excellent surface finish, almost unlimited intricacy. almost any metal can be cast. No flash to be removed or parting line tolerances. Ferrous, Non Ferrous. Medium and High Volume
Centrifugal Mold Metal or graphite mold is rotated in horizonal or vertical plane (true centrifugal method). Molten metal introduced into the revolving mold is thrown to the mold walls where it is held by centrifugal force until solidified. Rapid production rate, good soundness and cleanliness of castings. Ability to produce extremely large cylindrical parts. Existing mold for many sizes. Ferrous, Non Ferrous. Low, Medium and High Volume

Sand Molds Resin Shell Molds Ceramic Cope & Drag Invest
ment Cast
Plaster Mold Perma
nent Molds
Die Cast
First Inch Base Tolerance +/-.032" +/-.010"* +/-.007" +/-.008" +/-.005" +/-.015" +/-.002"
Additional Across Parting line +/-.032" +.020" +.010" .000" +.010" +.010" .001"
Size Range Oz.-Tons Oz.-175# 3-350# Oz.-45# Oz.-200# Oz.-100# Oz.-10#
As Cast Finish RMS 150/350 125/200 80/125 63/125 90 150/200 63/90
Draft (degree) 1 - 5 1/4 - 1 1/4 - 1/2 0 1/2 - 2 2 - 4 1/2 - 2
Design Intricacy Good Good Very good Excellent Very good Good Excellent
Minimum wall thickness 1/4" 7/32" 1/16" 1/16" 1/16" 3/32" 1/32"
* First inch tolerance, including parting line is +/-.030

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