Introduction to Die Casting
A Cost-Effective Method of Using High Pressure to Cast Metal Parts
Die casting is a cost-effective method to mass-produce lightweight metallic parts for household and industrial use.
Die casting is a metal forming method to manufacture metallic components by injecting molten metal alloys into a mold, or "die" at high pressure. Die casting is used to rapidly create metallic parts that require little post-manufacturing machining.
Die cast parts are generally fabricated from metallic alloys that have relatively low melting point. This protects the die from warping or cracking due to excess heat. Typical die-casting alloys include aluminum, zinc, magnesium, and copper.
The die itself is fabricated from high-strength steel, so it can withstand the heat of the molten metal and can be used for a large number of castings. Some dies can be used for hundreds of thousands of casts. A die generally consists of two halves that are clamped together. Additional parts can be included in the die, such as pins or sliders, to create more complex parts.
Die Casting Process
There are two different types of machines used in die casting:
- Cold Chamber: In cold chamber die casting, the molten metal is poured into a cylinder, or "cold chamber", that is connected to the die via a conduit called a gooseneck. A piston is then activated to force the molten metal into the die.
- Hot Chamber: In hot chamber die casting, the cylinder, or "hot chamber" sits within a bath of the molten alloy. In this case, when the piston is retracted, molten metal is drawn from the bath into the cylinder. The piston then pushes the molten metal into the die.
In both cases, after the metal has been injected into the die, the part is left to cool in the die. Some dies have cooling channels built into the die. A coolant is pumped through the channels to help remove the heat from the die and allow the cast part to cool faster.
After the part has cooled, it is removed from the mold. Some parts may have flash, or a thin metal extrusion around the part where the two halves of the die came together. The flash is removed with a flash die, or by hand with a grinder, depending on the part. Die-cast parts can be used as-is, or can be coated with paint or other types of coatings, such as chrome in the case of bath fixtures.
Die casting is used to create parts for a wide variety of applications from aircraft and automobile parts to plumbing fixtures and telecom enclosures. Die cast parts are generally lightweight and cost-effective to fabricate, compared to other manufacturing methods, and allow manufacturers to make quality products at competitive prices.
Source
North American Die Casting Association web site
