Green Sand Casting

A highly flexible process, greensand casting can be used for high volume, fully automated casting or for very low number of parts. Sand, bound with clay and water is used to make moulds around a pattern made of metal, wood or resin – metal is poured into the mould and once solidified, the sand can be re-used over and over again making greensand casting one of the most cost effective and environmentally friendly of all the casting processes.

Clay-bonded sands have provided the principal medium from which moulds for castings have been produced for centuries. In essence the mould material consists of sand, usually silica in the quartz form, clay and water. The water develops the bonding characteristics of the clay, which binds the sand grains together. Under the application of pressure, the mould material can be compacted around a pattern to produce a mould having sufficient rigidity to enable metal to be poured into it to produce a casting. When the mould is used in its moist condition it is referred to as green and the method of producing the moulds as the green sand moulding process. If the mould is dried at a temperature just above 100°C (212°F) the majority of the free moisture will be removed. This is the principal of the dry sand moulding process. Removal of the free moisture is accompanied by a significant increase in the strength and rigidity of the mould. This enables the mould to withstand much greater pressures and so, traditionally, the dry sand process has been used in the manufacture of large, heavy castings.

Typical applications are machine tools, sculptures, architectural, general engineering