Die casting is a very efficient technique to make things like lighting fixtures, vehicle spare parts, and many other components efficiently. However, not all metals and alloys can be subjected to die casting owing to their thermal properties. Some of the common metals that can be used in die casting are aluminum, brass, zinc, copper, and magnesium. There are five main stages in die casting and these are explained below.
Clamping
This step involves the preparation and clamping of the die parts. Usually, there will be two die halves that are cleaned and lubricated before clamping. With the size of the die cast aluminum part, the lubrication time, as well as the number of side cores and die cavities will increase. After proper lubrication, the two die halves are attached together inside the die cast machine and then securely clamped.
Injection
This step involves the transfer of the molten metal that is maintained at a set temperature in the furnace to a chamber from where it can be easily injected into the die. The transfer method used will depend on the type of machine being used in casting, i.e. whether a hot chamber machine or a cold chamber machine is used.
Cooling
Once the molten metal enters the die cavity, it starts to cool down and solidify, and when the cavity is completely filled with the molten metal, it will form the shape of the casting. The die will not be opened until the metal is cooled down and the casting has solidified properly. The cooling time will depend on many factors like the complexity of the die and wall thickness of casting.
Ejection
After elapse of the cooling time, die casters open the die and make use of an ejection mechanism to push out the casting from the cavity. The size of the envelope of the casting will determine the ejection time and the mechanism used to eject the casting may apply pressure to eject the casting, as during the cooling phase, the casting will shrink and may hold on to the die.
Trimming
During the cooling phase, the materials that are present in the channels of the die can get attached to the casting. This material together with the flash that may have occurred, need to be trimmed manually or with a trimming press. Manual trimming involves cutting or sawing and the time required for trimming will depend on the size of the envelope.