The Process of Metal Parts Casting You Must Know About

Hot chamber die casting

During the process of hot chamber Metal Die Casting, the metal die casting machine contains the necessary equipment required for heating the metal to a molten state. As it is a self-contained system, it is much faster than the alternative but it is only suitable for a selection of casting materials, which includes zinc, tin, and lead alloys.

Cold chamber die casting

The cold chamber die casting process may need to use a separate furnace to heat the metal. This slows down the process, as the molten metal can be brought to the die casting machine with the help of a ladle. However, because a separate furnace is much more powerful than a hot chamber die casting machine, metals with high melting points can be cast. For aluminum casting, this method is suitable and is preferred by Metal Die Casting Company.

The metal die casting process typically proceeds as follows regardless of whether a hot chamber or cold chamber machine is used:

• Shakeout
• Filling
• Ejection

Mold preparation

During mold preparation, the interior surfaces of the two die halves have to be coated with a lubricant so that it can facilitate ejection once the castings are complete. With locking pins, the die halves can then be closed and secured.

Using a pressure system, the filling of the mold can be achieved. In both cases, the result is a molten metal that is being forced into the mold cavity via the sprue. In a hot chamber, high pressures up to 35 megapascals and in a cold chamber 140 megapascals make sure of a fast and comprehensive filling, which in turn leads to consistent cooling that prevents uneven shrinkage and consequent part deformation. During cooling, pressure is highly maintained. 

The two die halves are then opened and to remove the castings the ejector pins are used. Typically, the dies are then immediately re-closed and then they are ready for the next shot. Meanwhile, the finished castings are ready for the next shakeouts which are then supplied by a Metal Die Casting Supplier. It includes removing scrap sections of the shot such as sprues, runners, and flash (seepage of material at the parting line). Using manual tools, tumbling, or with a hydraulic trim die this material removal can be achieved.

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