Die Casting Process

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 fast velocity and under high pressure into reusable steel dies. Compared to other casting processes, die casting is at the top end of both velocity and pressure. The high velocity translates into very turbulent flow condition. 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.

Commonly used metals in die casting process for making the moulds are die steel, tool steel, tungsten carbide, etc.
The die casting is used only for producing low melting point metals like Aluminium, Lead, Tin, Zinc, Cadmium, etc.

It is of two types

1. Gravity Die Casting
2. Pressure Die Casting

1. Gravity Die Casting

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

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

2. Pressure Die casting

• If the flow molten into the casting cavity is due to the application of external pressure is called as pressure die casting.
• Hence complex shape of casting can be produced easily.

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

Features of Die casting process:

1. Due to metal molds used, this process produces a fine grained casting with superior mechanical properties.
2. Produces very good surface finish of 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. Cost of die is very high.
7. Not all metals can be casted.