Green Sand Casting
Green sand is growing in popularity as more casters are recognizing the properties of this method. If you have traditionally used regular Sand casting, green sand casting will prove to be easier to work with and will produce better casts.
The suitable material:grey iron;ductile iron;aluminium;copper etc.
Casting weight can vary from ounces to 50,000 pounds or more.
Pattern costs are the most economic compared to other casting processes
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This forms a "green" mold which must be dried to receive the hot metal. If the mold is not sufficiently dried a steam explosion can occur that can throw molten metal about. In some cases, the sand may be oiled instead of moistened, which makes possible casting without waiting for the sand to dry. Sand may also be bonded by chemical binders, such as furane resins or amine-hardened resins.
Many experienced metal casters will continue to use sand casting even though their abilities and resources allow them to use the other metal casting methods like Lost Wax Casting or Investment Casting. Sand casting involves less material and less effort than the other casting methods. Sand casting is a great way for new casters to get into the trade.
In sand casting, the metal caster will create a mold by placing an original in the flask which is filled with sand. The original will be a pattern of what you want to cast. By ramming or vibrating the sand, the caster creates a mold of the original. The casting sand used needs to be able to retain the shape of the mold. Finding the right mixture of sand to water is crucial. Too much water can ruin the mold and possibly destroy it while too little water will create a poor casting. Green sand is a type of casting sand that many prefer since its ability to retain the shape of the mold is far better then normal sand. Green sand usually contains bentonite clay, sand, and water.
After the sand is packed, the pattern or original is removed carefully. Molten metal is poured into the mold and allowed to cool. The metal caster will then break the mold and dig out the casting.
While sand casting has its benefits the use of green sand can greatly increase the likelihood of a successful casting. Green sand is not really green the color refers to the damp nature of the sand. Green sand is created by adding water and bentonite to the sand. One of the benefits of using bentonite in green sand is that it makes the sand more permeable which allows more gas to escape.