Commonly used in the manufacturing industry, die casting is a casting process that involves forcing molten metal through the cavity of a pre-shaped mold. Base metals such as zinc, aluminum, copper, magnesium and lead are first heated until they achieve a molten state. The newly molten metal is then forced into a pre-shaped mold using pressure. Once the molten metal has cooled and hardened, it’s removed from the mold. With that said, there are two different types of die casting processes: hot and cold.
Overview of Hot-Chamber Die Casting
Hot-chamber die casting uses the same process previously mentioned — molten metal is forced through the cavity of a pre-shaped mold using pressure. The defining characteristic of hot-chamber die casting is that metal is heated inside the casting machine rather than a separate machine or furnace.
Also known as goose-neck machines, hot-chamber casting machines feature a built-in furnace in which metal is heated to achieve a molten state. They use a hydraulic-powered piston that forces molten metal out of the furnace and into the die. Hot-chamber die casting is a relatively fast process, with a typical cycle lasting just 15 to 20 minutes. While not suitable for metals with a high melting point, it’s ideal for zinc alloys, tin alloys and lead alloys.
Overview of Cold-Chamber Die Casting
Based on its name, you may assume that cold-chamber die casting involves forcing cold metal through the cavity of a mold, but this isn’t necessarily true. Cold-chamber die casting still requires the use of molten metal that’s forced into a mold. The difference between these two processes is that hot-chamber die casting heats metal inside the casting machine, whereas cold-chamber die casting involves heating metal in a separate furnace and then transferring the newly molten metal into the casting machine.
With cold-chamber die casting, metal is first heated to achieve a molten state in a separate furnace. The molten metal is then transported to the casting machine where it’s fed into the machine’s chamber. The machine uses a pressurized plunger to force the molten metal into the cavity of the mold.
Certain types of metals — those with a high melting point — can only be processed using cold-chamber die casting. The high temperatures required to achieve a molten state for metals such as aluminum, magnesium and copper means a separate furnace must be used, which is why some manufacturers choose cold-chamber die casting over hot-chamber die casting.