Types of Moulding Sand Part-2

Types of Moulding Sand:

5. Facing Sand:

 Facing Sand

The face of the mould is made by facing sand. Facing sand is employed directly next to the surface of the pattern and it comes in direct contact with the molten metal, when the molten metal is poured into the mould. It possesses high strength and refractoriness because it comes in touch with the molten metal. It’s made from clay and silica sand without addition of any used sand.

6. Backing Sand:

 Backing Sand

Backing sand or flour sand is employed to copy facing sand. Old and repeatedly used moulding sand is employed for the backing purpose. It’s also sometimes called black sand due to the addition of coal dust and burning when it comes in touch with the molten metal.

7. System Sand:

 System Sand

In mechanical sand preparation and handling units, facing sand isn't used. The sand which is employed is cleaned and reactivated by adding of water, binder and special additives. And therefore the sand we get through this is often called system sand. System sand is used to fill the entire flask within the mechanical foundries where machine moulding is employed. The mould made with this sand has high strength, permeability and refractoriness.

8. Core Sand: 

 Core Sand

The sand which is employed to form core is named core sand. It’s also called as oil sand. It’s a mix of silica sand and core oil. Core oil is mixture of flaxseed oil, resin, light oil and other binding materials. For the sake of economy, pitch or flours and water could also be utilized in making of huge cores.