Die Casting Process

The die casting process is a manufacturing process for producing accurately dimensioned, sharply defined, smooth or textured surface metal parts. It is accomplished by injecting liquid metal at a fast velocity and under high pressure into reusable steel dies. Die casting is at the top end of both speed and pressure compared to other casting processes. The high velocity translates into a very turbulent flow condition. The die-casting process is often described as the shortest distance between raw materials and the finished product. The term die casting is also used to identify the cast product.

Schematic diagram of the die casting process

Commonly used metals in the die casting process for making the molds are steel, tool steel, tungsten carbide, etc. Die casting is used only for producing low-melting-point metals, Such as Aluminum, Lead, Tin, Zinc, and cadmium.

It is of two types

1. Gravity Die Casting
2. Pressure Die Casting

1. Gravity Die Casting

1. If the molten metal is flowing into the cavity due to gravitational force, the process is called gravity die casting.
2. Therefore, gravity die casting is only used for producing simple parts.

Ex: I.C. engine piston made by using aluminium alloy.

2. Pressure Die casting

1. If the molten material flows into the casting cavity due to the application of external pressure, it is called pressure die casting.
2. Hence, complex shapes of casting can be produced quickly.

Ex. I.C. engine carburetor made of aluminium alloy.

Features of the Die casting process:

1. Due to the use of metal molds, this process produces a fine-grained casting with superior mechanical properties.
2. Produces a perfect surface finish of an order of 4 microns or better.
3. Close dimensional tolerance can be obtained.
4. This process is economical for large-scale production.
5. Complicated shapes can not be produced.
6. The cost of the die is very high. Not all metals can be cast.