Additional Casting Methods

At Kovatch Castings, we always strive to help you navigate to the best option and a company that can create your part as efficiently as possible. Read on to learn about additional casting methods, or contact us and let us help with your questions.

(The following information is intended as educational material. Actual specs and lead times can vary depending on foundry.)

Sand Casting

If you’ve lifted weights, you’re familiar with the rough surface of a sand casting. This is due to the fact that sand casting cannot hold a net shape. How does it work? Tempered sand is packed onto wood or metal pattern halves, removed from the pattern, and assembled with or without cores. Metal is poured into resultant cavities. Various core materials can be used. Once the process is complete, the molds are broken to remove castings.

• Metals: Most castable metals
• Lead time: Samples may take two to 10 weeks. Production may take two to four weeks after sample approval. If you can accept the surface condition and more dimensional variations, this option might be your best low cost alternative.

Die Casting

Common in automotive and high production, a die casting is very similar to permanent mold. In die casting, the molten metal is injected under pressure into hardened, steel dies and then often water-cooled. Once the process is complete, the dies are opened and castings are ejected.

• Metals: Aluminum, zinc, magnesium, and limited brass. No steel alloys can be poured using this process.
• Lead time: Samples may take six to 14 weeks. Production may begin ASAP after sample approval.

Permanent Mold

Very similar to die casting, permanent mold casting sees molten metal gravity-poured into cast iron molds and coated with ceramic mold wash. Cores can be metal, sand, sand shell, or other material. Once the process is complete, the molds are opened and castings are ejected.

• Metals: Aluminum, zinc, some brass, bronze, H.C. copper, lead, and gray iron
• Lead time: Samples may take eight to 20 weeks. Production may take four to eight weeks after sample approval.

Plaster Mold

With a plaster mold, a plaster slurry is poured onto pattern halves and allowed to set. The mold is removed from the pattern, baked, and assembled. Metal is poured into the resultant cavity. Once the process is complete, the molds are broken to remove castings.

• Metals: Aluminum, brass, bronze, zinc, beryllium, copper, and magnesium
• Lead time: Samples may take two to six weeks. Production may take two to four weeks after sample approval.

Graphite Mold

A graphite mold is the same as a permanent mold. The key difference is that no ceramic mold wash is needed since graphite molds are used. Core pins are usually steel.

• Metals: Aluminum, zinc, and zinc aluminum
• Lead time: Samples may take two to 10 weeks. Production may take four weeks after sample approval.

Resin Shell Mold

Resin-coated sand is poured onto hot metal patterns, curing into shell-like mold halves. These are removed from the pattern and assembled with or without cores. Metal is poured into the resultant cavities. Once the process is complete, the molds are broken to remove castings.

• Metals: Most castable metals
• Lead time: Samples may take twelve to sixteen weeks. Production may take two to 10 weeks after sample approval.

Metal Injection Molding

With metal injection molding, a very fine metal powder is combined with binder material and injected into a die. The part is then ejected. The binder is melted or dissolved and vacuum sintered, resulting in 94-99% of theoretical density.

• Metals: Primarily ferrous alloys, titanium, and kovar
• Lead time: Samples may take eight to 12 weeks. Production may take four to six weeks after sample approval.

Powder Metal

Metal powder is compressed into a die barrel between moving upper and lower punches. The lower punch ejects the part which is then sintered and sized if close tolerance is required.

• Metals: Iron and iron alloys, copper, bronze, brass, stainless steel, aluminum
• Lead time: Samples may take six to 14 weeks depending on part complexity. Production may take three to eight weeks after sample approval.

V-Process

Extremely fine sand is “vacuum packed” around pattern halves. The pattern is removed and metal is poured into the cavity. Once the process is complete, the vacuum is released and the casting is removed.

• Lead time: Samples may take two to six weeks. Production may take two to six weeks after sample approval.

Source: Special Metal Supply’s “Guide to the Proper Selection of Casting Techniques,” accessed March 2019.

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