Green Sand Casting :
A commonly used form of sand casting, green sand casting gets its name because wet sand is used in the molding process. A variety of additives like pitch, cellulose and silica flour are used in this process. The aggregate of sand mold consist of mixture like silica, clay, water and other materials are taken for bank sands or lake sands. The main advantage of green sand casting is that the sand can be used any number of times after adjusting the composition. Raw sand are obtained and processed to provide a consistent distribution of grain sizing. A variety of additives such as pitch, cellulose, and silica flour are used in the process.
Molds for sand casting :
In green sand casting process lake or bank sand is used as the aggregate and different kinds of additives are used like pitch, cellulose and silica flour. A sand mixture is made of sand, grains, clay, water and other material according to the casting requirements. The patterns is then mounted on a mold board and a suitable flask in placed around it.
Green sand mold is rammed around the pattern and when the pattern is removed there will be a suitable mold cavity. The sand mixture is rammed around the pattern and sometimes automated machines are used to vibrate the sand in the mold. In the mold the molten metal is poured and when it solidifies the cast is removed from the mold. Mold release agents can be used, but commonly the mold is broken to remove the cast. The mould can be again processed and reused in the next castings.
Green sand casting is used largely for heavy casting like casting bells, where the casting are to be cleaned and polished for fine surface finish.
- A reasonably priced process, green sand casting enables great flexibility in the choice of molds and patterns.
- This is an environmental friendly process where there mold aggregated can be treated and repeatedly used.
- This process enables speedy, economical and expeditious execution of the casting process
- Easily adaptable to automated and semi-automated machines for some process.
- The aggregate and adhesives are readily available at reasonable rates.
Original Source: https://mechanicalinfo.wordpress.com/2011/10/31/green-sand-casting/