Mould cavity-

The mould cavity which holds the liquid metal is complementary to the final product. The mould material, therefore, must withstand the superheated liquid metal. For single castings, the mould is cereal, with water.

Shake allowance-

The vertical faces of mould cavity gets enlarged due to shaking or tapping of pattern for easy removal from mould. This causes slight enlargement of mould cavities and often a negative allowance in the form of shake allowance is provided to compensate for this enlargement.

Distortion allowance-

In order to prevent distortions, particularly in long and thin sections, U and V-sections of castings, and in irregular-shaped castings, often extra material in the form of distortion allowance is provided.

Machining and finishing allowance-

Since the surface finish and dimensional accuracy achieved by casting is not very good, certain extra metal is provided on the casting which can be removed during finishing. This extra material is called the Machining and finishing allowance and is typically in the range of 1.5 to 9.0mm, depending upon the material and size of casting and the finish required.