Types of Moulding Sand

Types of Moulding Sand Points : Types of Moulding Sand, Core sand, Facing sand, Baking Sand, Green sand, Parting sand, Dry sand, System Sand, Loam Sand Core sand Sand which is used for making cores is called “core sand” or “oil sand”. It is silica sand mixed with core oil, which is composed of linseed oil, resin, light mineral oil and other binders Facing sand It forms a fine face of the mould. It is used directly next to the surface of the pattern and it comes into contact with the molten metal when the mould is poured. It is therefore, subject to the most severe conditions and hence must possess high strength and refractoriness. It is made of silica sand and clay, without the addition of used sand. Baking Sand Core sand is mixed with a binder who holds the form of the core while it is being - baked in the core oven, and as it is used in the mould. There are four common core binders used in core making: water soluble binders, oil binders, pitch, and rosin binders. Oil binders are the most convenient for small shops. Linseed oil or fish oil is often used for core oils. Foundry molasses, a by-product of the manufacture of industrial alcohol, is also a good core binder. Green sand It is also called natural sand, have more or less moist state, It is a mixture sand with 18 to 30% clay and 6 to 8% water. The clay and water give bonding strength green sand: It is fine, soft, light and porous. Being damp, when squeezed in retains shape given to it under pressure. Moulds prepared in this sand are knows Green Sand Mould. Parting sand A mould is generally prepared in two or three boxes. These boxes are separated from adhering to each other by spreading fine sharp dry sand called “parting sand”. Parting sand is also used to keep the green sand from sticking to the pattern. It is clean clay-free silica sand. Some time burnt core sand, i.e. core sand cleaned from castings. These are also manufactured parting materials known as “parting compounds”. They are in powdered from and used by dusting them one parting surface. Dry sand The mold prepared in green sand are dried or baked to remove all most all moisture of the moist sand. The structure in the moulding boxes becomes stronger and compact. Venting is necessary but not so much as required in green sand. System Sand A sand working in mechanical sand preparation with handling system is call system sand. This sand has elevated strength, permeability with refractoriness. Loam Sand A combination of 50 percent sand grains with 50 percent clay is call loam sand and is use for loam moulds of large Grey iron casting.