Marketplace Pulse: Die Casting RFQs

Die casting is the process of forcing molten metal under high pressure into mold cavities (which are machined into dies). Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminum, magnesium, lead, and tin based alloys, although ferrous metal die castings are possible. The die casting method is especially well suited for applications where a large quantity of small- to medium-sized parts requires accurate details, fine surface quality and dimensional consistency.

Clamping – the preparation and clamping of the two halves of the die. Each die half is first cleaned from the previous injection and then lubricated to facilitate the ejection of the next part.

Injection – The molten metal maintained at a set temperature in the furnace, is transferred into a chamber where it can be injected into the die. The method of transferring the molten metal is dependent upon the type of die casting machine, whether a hot chamber or cold chamber machine is being used. This pressure, from 1,000 to 20,000 psi, holds the molten metal in the dies during solidification. The amount of metal that is injected into the die is referred to as the shot. The injection time is typically less than 0.1 seconds, in order to prevent early solidification of any one part of the metal.

Cooling – The molten metal will begin to cool and solidify once it enters the die cavity. When the entire cavity is filled and the molten metal solidifies, the final shape of the casting is formed. The die can not be opened until the cooling time has elapsed and the casting is solidified.

Ejection – After the cooling time has passed, the die halves are opened and an ejection mechanism pushes the casting out of the die cavity. The ejection mechanism must apply some force to eject the part because during cooling the part shrinks and adheres to the die. Once the casting is ejected, the die can be clamped shut for the next injection.

Trimming – The material in the channels of the die will solidify attached to the casting. This excess material, along with any flash, must be trimmed from the casting. The scrap material that results from this trimming is either discarded or can be reused in the die casting process. Recycled material may need to be reconditioned to the proper chemical composition before it can be combined with non-recycled metal and reused in the die casting process.