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