Casting is a manufacturing process to shape materials. There are many engineering methods to shape a piece of material, machining processes generally requires a lot of process time. In the big industries, time is money, and people would generally want to cut down machining time to produce materials of similar shapes and integrity.
Analogous to making ice in the ice cube tray, casting essentially is the process of placing a liquid material into a solid mold and let it solidifies. Then these casted materials may be sent for machining processes to remove the flashes or dribs and drabs on the material surface.
Die casting is one of the casting methods used in metallurgy. The mold employed for use is called a die that is specially designed and made in shape for the purpose. The liquid metal is placed into the cavity of the die and then pressed under high pressure for a period of time for it to take the desired shape while solidifying.
Important components in a die casting operation are: plunger, chamber, and of course, the die.
The plunger is a piece of equipment to that works like a syringe plunger, where you apply force to expel the liquid in it. The plunger serves the function of preventing the liquid metal from coming out of the die when the high pressure is being applied. Also, the high pressure is also applied at this plunger to make sure the liquid metal flow into the cavity of the die fully, so that the sophisticatedly-shaped metal can be produced correctly. It also serves to maintain this high pressure, so that the liquid metal cannot flow while it is in the liquid state.
The chamber is the metal feed system for the input of liquid metal for the insertion into the die. For cold chamber die casting, this chamber is usually a straight cylinder that directly leads to the die cavity. In hot chamber casting, this chamber takes the form of a gooseneck (and it is an equipment of the same name).
COLD CHAMBER DIE CASTING
In cold chamber die casting, there are additional components like the ladle used for liquid metal feed. This ladle transfer the liquid metal from a source into the chamber and then the plunger (or called cylinder) injects the liquid metal into the die cavity. Only during the hot liquid metal feeding step the chamber is heated, for the rest of the process, the chamber is not heated. This is how the process got its name.
This casting method is used for metals with high melting points and can erode the parts in the chamber or plunger. This is to reduce the time of contact between the molten metal and the susceptible parts.