Pressure die casting is a process where metal is melted and forced into steel dies. The metal hardens into the desired shape. Molten metal is injected into a die cavity through a channel by movement of a plunger. After a preset solidification time, the plunger reverses direction, the part is ejected, and the machine is ready for the next cycle.
In hot chamber casting a plunger traps a certain volume of molten metal and forces it into the die cavity through a gooseneck and nozzle. Metals having low melting points such as zinc, copper, magnesium and lead are cast using hot chamber die casting. In cold chamber casting molten metal is poured into the injection cylinder. The metal is forced into the die cavity at high pressures. High melting point alloys of aluminum and copper are normally cast using cold chamber die casting.
Pressure die casting creates parts with no joints by eliminating other processes such as welding and fastening. Integral fastening elements such as bosses and studs can be included. Good dimensional accuracy and detail is possible. No further machining required usually. Casting offers low cost after amortization of tooling.
Pressure die casting can produce a wide variety of complex 3D shapes provided that the shape can be ejected from the mold. Typically this requires walls with draft.
Some examples of use of die casting include engine blocks, toy components, bushings, levers, gears, and assorted parts used in the automotive, aerospace and medical industries, etc.
Pressure die casting can process nonferrous alloys that have low melting points: aluminum, zinc, magnesium, copper, lead, tin, silver, etc.
The process requires custom steel tooling in the negative shape of the final part.
To reduce costs, minimize size, complexity and material volume.
- A parting line (location where the two mold halves meet) will occur.
- Some flashing will occur at the parting line.
- Marks from ejector pins (rods that push the part out of the mold) may occur.
- Provide a shape that can easily be ejected from the mold.
- Keep wall thickness uniform.