#manufacturingprocess #polytechnic #mouldingsand
PROPERTIES OF MOULDING SAND
Good moulding sand must have the following properties
Porosity or permeability
Plasticity
Adhesiveness
Cohesiveness
Refractoriness
1. Porosity or permeability :
When molten metal is poured into the mould, steam and gases will be formed. If the gases are not removed, casting defects such as blowholes will occur. This property by which moulding sand allows the gases to go outside is called porosity or permeability.
2. Plasticity :
This is the property by which the moulding sand gets the shape of the pattern in the mould and retains the shape.
3. Adhesiveness :
This is the property by which the sand particles stick or adhere to another body. The moulding sand sticks to the side of the moulding boxes by this property. The moulding sand does not fall out of the box because of adhesiveness.
4. Cohesiveness :
It is the property by which sand particles stick together. It is called the strength of sand. Because of this property, mould remains strong and does not break when molten metal is poured.
5. Refractoriness :
This is the property of moulding sand to resist the high temperature of molten metal. By this property, the moulding sand withstands high temperature and does not melt.
Preparation of Moulding sand :
Moulding sand is prepared by the following steps:
Mixing of sand
Tempering of sand
Conditioning of sand.
If you want to know about moulding sand : • MANUFACTURING PROCESS ...