Green Sand Casting
What is Green Sand Casting?
Green Sand Casting is mainly differed with resin sand casting . The mould sand is taken from rivers, and then put some others in sand to increase their viscidity.
Green sand is an aggregate of sand, bentonite clay, pulverized coal and water. Its principal use is in making molds for metal casting. The largest portion of the aggregate is always sand, which can be either silica or olivine. There are many recipes for the proportion of clay, but they all strike different balances between moldability, surface finish, and ability of the hot molten metal to degas. The coal, typically referred to in foundries as sea-coal, which is present at a ratio of less than 5%, partially combusts in the presence of the molten metal leading to offgassing of organic vapors. Read more
Sand Casting Process
A sand casting is also divided resin sand casting and green sand casting. sand casting is produced when molten metal is poured at atmospheric pressure into a cavity formed in a compacted molding sand. In typical ferrous casting, the mold would be bonded with 6 to 8 percent western bentonite mulled with 2 to 3 percent water. Patterns would be reusable, but the sand molds would be broken from the casting after the solidified casting had cooled sufficiently. The sand would be returned to the muller for recycling by mulling with some new clay and water to reactivate the old clay. Sand moulds define the external geometry of a casting, whereas cores define the interior or undercuts.
The sand casting comprison
The sand casting comparison : green sand casting with resin sand casting; investment casting compare.
| sand casting process | production way | order quantity | quality price | weight(referance) |
| green sand casting better for iron and light alloy aluminum copper alloy | making mould by hands | smaller | pass | no requirement |
| making mould by lift-machine | more | normal | under 20kg | |
| making mould by simple-machine | middle | superior | under 30kg | |
| making mould by production-line | larger | excellence | under 100kg | |
| Resin sand casting better for iron,normal for steel | baking | smaller and middle | superior | over 5kg |
| no baking | smaller and middle | superior | over 10kg | |
| no baking by production-line | larger | superior | over 30kg | |
| Sodium silicate bonded sand casting better for steel | baking | smaller and middle | normal | over 5kg |
| no baking | smaller and middle | pass | over 10kg | |
| dry mould casting better for iron and light alloy | baking | smaller and middle | pass | over 50kg |
what is Electric Arc Furnace?
Electric Arc Furnace is a furnace that heats charged material by means of an electric arc.
Arc furnaces range in size from small units of approximately one ton capacity (used in foundries for producing cast iron products) up to about 400 ton units used for secondary steelmaking. Arc furnaces used in research laboratories and by dentists may have a capacity of only a few dozen grams. Electric arc furnace temperatures can be up to 1,800 degrees Celsius. Arc furnaces differ from induction furnaces in that the charge material is directly exposed to the electric arc, and the current in the furnace terminals passes through the charged material.
Electric Arc Furnace can get better steel than induction furnace. The steel from electric arc furnace has less of sulfur and phosphorus. Then it’s mechacnical property will be good.
electric arc furnac
What is sand castings?
Sand casting is used to make large parts (typically Iron, but also Bronze, Brass, Aluminum). Molten metal is poured into a mold cavity formed out of sand (natural or synthetic). The processes of sand casting are discussed in this section, include patterns, sprues and runners, design considerations, and casting allowance.
Patterns
casting pouring system
The cavity in the sand is formed by using a pattern (an approximate duplicate of the real part), which are typically made out of wood, sometimes metal. The cavity is contained in an aggregate housed in a box called the flask. Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages. Cores are placed in the cavity to form holes of the desired shapes. Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold. A riser is an extra void created in the mold to contain excessive molten material. The purpose of this is feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting.
