Die Casting Processes
During the cold-chamber die casting process, the molten charge (more material than is required to fill the casting) is ladled from the crucible into a shot sleeve, where a hydraulically operated plunger pushes the metal into the die. The extra material is used to force additional metal into the die cavity to supplement the shrinkage that takes place during solidification. The principle components of a cold-chamber die casting machine are shown below. Injection pressures over 10,000 psi or 70,000 KPa can be obtained from this type of machine.
Operating Sequence of the Cold-Chamber Die Casting Process
- The die is closed and the molten metal is ladled into the cold-chamber shot sleeve.
- The plunger pushes the molten metal into the die cavity where it is held under pressure until solidification.
- The die opens and the plunger advances, to ensure that the casting remains in the ejector die. Cores, if any, retract.
- Ejector pins push the casting out of the ejector die and the plunger returns to its original position.