What is Cold Chamber Die Casting Process?
Cold chamber die casting is a casting process in which the molten metal is introduced into the mold cavity from the external source.
This external source from which the molten metal is introduced is known as cold chamber.
Die Casting Process (Steps)
Cold chamber die casting is a permanent mold metal casting process, in which reusable mold, gating system, etc are employed.
The mold is made up of steel metal blocks in two halves that can be opened and closed.
The pressure exerted by the molten metal on the mold is very high. So the molds are needed to be clamped using a large robust machine known as die casting machine.
The cold chamber (also known as shot chamber) is located at the entrance of the mold.
The piston is attached with this chamber which is further connected to the power cylinder.
The lubricant is applied at the inner surface of the mold so that the molten metal does not stick to the mold.
Now, the correct amount of molten metal is poured into the cold chamber (or shot chamber) from the external source. (See below diagram).
Now as the piston moves further, the intake port is cut off and the molten metal moves towards the mold cavity.
Due to the pressure exerted by the piston, the molten metal reaches the mold cavity with a high pressure.
Because of high pressure, the molten metal fills even in the thin portions of the mold, so that good surface details can be achieved.
The pressure is maintained until the metal gets solidified.
Once the metal is solidified, the pressure is released and the mold is opened to remove the castings.
The ejector pins are used to remove the solidified casting from the mold.
The lubricant is sprayed in the inner surface of the mold and then the process is repeated for the other casting.
In this way, castings with good surface details are manufactured by using cold chamber die casting process.