Casting Process Introduction

Casting Definition:

Casting is a manufacturing process by which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process.

There Are Different Types Of Casting Process:

1. PERMANENT MOLD OR GRAVITY DIE CASTING

This process is commonly known as permanent mold casting in U.S.A and gravity die casting in England.

A permanent mold casting makes use of a mold or metallic die which is permanent.

Molten metal is poured into the mold under gravity only and no external pressure is applied to force the liquid metal into the mold cavity. However, the liquid metal solidifies under pressure of metal in the risers, etc.

2. SLUSH CASTING

Slush casting is an extension of permanent mold casting or metallic mold casting.It is used widely for production of hollow casting without the use of core.The process is similar to metallic mold casting only with the difference that mold is allowed to open at an early stage and some un-solidified molten metal fall down leaving hollowness in the cast object.

3. PRESSURE DIE CASTING

Unlike permanent mold or gravity die casting, molten metal is forced into metallic mold or die under pressure in pressure die casting.The application of high pressure is associated with the high velocity with which the liquid metal is injected into the die to provide a unique capacity for the production of intricate components at a relatively low cost.

Die casting is widely used for mass production and is most suitable for non-ferrous metals and al1oys of low fusion temperature. The casting process is economic and rapid. The

surface achieved in casting is so smooth that it does not require any finishing operation.

4. Hot chamber die-casting

Hot chamber die-casting machine is the oldest of die-casting machines which is simplest to operate.

5. SHELL MOLD CASTING

Shell mold casting process is recent invention in casting techniques for mass production and smooth surface finish.It consists of making a mold that possesses two or more thin shells thermosetting resin bonded sands.

6. CENTRIFUGAL CASTING

In centrifugal casting process, molten metal is poured into a revolving mold and allowed to solidify molten metal by pressure of centrifugal force.Due to centrifugal force, the castings produced will be of high density type and of good strength.

6. CONTINUOUS CASTING

In this process the molten metal is continuously poured in to a mold cavity around which a facility for quick cooling the molten metal to the point of solidification. The solidified metal is then continuously extracted from the mold at predetermined rate.