Molding sand can also be classified according to their use in a number of varieties which are described below.
1) Green sand also known as tempered or natural sand is just prepared mixture of silica sand with 18 to 30 percent clay, by 6-8% moisture content. The clay and water to bring the band to the green sand. It is fine, soft, light, and porous. Green sand humidity is, when pressure in the arm and it retains the shape and sense to him under pressure. Models prepared by the sand not requiring support and thus is known as green sand molds. The sand is easily available and it possesses a low cost. It is commonly employed for the production of ferrous and non-ferrous castings.
2) Dry sand, green sand is dried or baked in an oven suitable after the mold and cores, called dry sand. It possesses greater strength, rigidity and thermal stability. It is primarily suitable for larger castings. Mold are prepared in the sand dry sand molds.
3) sand Loam, Loam is a mixture of sand and clay with water to thin plastic paste. Held high clay Loam sand as much as 30-50% and 18% water. Patterns not used for molding loam and mold shape for brushing. This is especially employed for molding loam used for large gray.
4) Facing sand, sand Facing have just prepared and the face of the model forms, surface finish gives solutions. It is directly adjacent to the surface of the pattern and it comes in contact with molten metal when the mold poured. A wide front shield pattern and thus from the surface by the. The sand under the severest conditions and must, therefore, high strength refractoriness. It is made of silica sand and clay, without the use of sand used.
5) Support sand or sand floors used to support the front and sand used to fill the entire volume of the flask shape. Used molding sand is mainly employed for this purpose. The sand is supported sometimes called black sand because of age, molding sand repeated use black in color due to excess dust and burning coal is coming into contact with the molten metal.
6) Separation sand without binder and moisture are used to keep the green sand without following the pattern and also to allow the separation of sand on the surface of the handle and pull the separation without clinging.
7) Core sand used for making cores and is sometimes also known as oil sands. The high silica rich sand mixed with oil binders such as a central oil consists of linseed oil, resin, light mineral oil and other bound materials.