Die casting is referred to the process of forcing molten metal under high pressure into mold cavities. There are 4 steps in the process. First, the mold is sprayed with lubricant and closed. The lubricant helps control the temperature of the die and assists in the removal of the casting. Molten metal is then shot into the die under high pressure between 1,500~25,000 psi. Once the die is filled the pressure is maintained until the casting has solidified. The die is then opened and the part is ejected by the ejector pins. Finally, the scrap, which includes the gate, runners, sprues and flash are trimmed off either manually or by trimming die. The scrap is recycled by re-melting it.

Typical materials for die casting are non-ferrous metals. The most popular are aluminum and zinc alloy, and occasionally magnesium alloy. Due to the high pressure and high temperature used in the process, the die cast mold is the most expensive of all other processes. Therefore it is not hard to understand that the die casting method is especially suited for applications where a large quantity of small to medium sized parts are needed with good detail, fine surface quality and dimensional consistency.

For low volume and large size aluminum parts, try investment casting which has low tooling cost but the piece price is relatively high. Or permanent mold casting which tooling cost is about 2/3 of the die casting. Or if surface and dimensional requirement are not very high, try sand casting.