Page 12 - Module DMV20173

2.0 CASTING PROCESSES

2.3 PROPERTIES OF MOULD

1. Basically, properties of mould controls the properties of end casting products.

2. Several mould properties should be considered before implementing casting
processes such as design, size, product, cost, weight etc.
3. The major categories moulds are as follows:
a) Expendable moulds.

b) Permanent moulds.
c) Composite moulds.

2.4 EXPENDABLE-MOULD CASTING PROCESSES

1. In expendable-mould casting, as the molten metal solidified, the mould that used in
casting process is broken up to remove the casting.

2. The major categories of expendable-mould casting are sand, shell mould, plaster
mould, ceramic mould, evaporative pattern, and investment casting.
3. Generally these casting moulds are mixed with various binders (bonding agents) for
improved properties.

2.4.1 SAND CASTING

1. Sand casting is a casting technique that applied in almost any metal cast.
2. Most sand-casting operations use silica sand as mould material.
3. Sand casting applied with no limit to size, shape, weight and low tooling cost.
4. Sand is inexpensive and is suitable as mould material because of its high-

temperature characteristics and high melting point.
5. Good permeability of moulds and cores allows gases and steam evolved during the
casting to escape easily.
6. Figure 3.3 shows the outline of production steps in a typical sand-casting operation.

Think
What is permeability?

Permeability means; allow escape of gas, function of sand practical size,
bonding agent and moisture.

BPLK 44 DMV 20173