Die Casting Process is divided into hot-chamber die cas […]
Die Casting Process is divided into hot-chamber die casting machine and cold chamber die casting machine two categories. Hot-chamber die-casting machine with a high degree of automation, less material loss, higher production efficiency than the cold chamber die-casting machine, but subject to heat capacity constraints, is still only used for low-melting zinc alloy, magnesium alloy casting materials . Today's widely used aluminum die-casting, due to the higher melting point, can only be produced in the cold chamber die-casting machine. The main feature of die-casting is that the molten metal fills the cavity under high pressure and high speed and is shaped and solidified under high pressure. The disadvantage of die-casting is that because the molten metal is inevitably filled in the cavity under high pressure and high speed.
The air trapped in the cavity inside the casting, the formation of subcutaneous pores, so aluminum alloy die-casting heat treatment is not appropriate, zinc alloy die casting surface should not spray (but can be sprayed). Otherwise, the inner pores of the casting are heated in the above-mentioned treatment, which will cause deformation or bubbling of the casting due to thermal expansion. In addition, die-casting machining allowance should also be made smaller, usually about 0.5mm, both to reduce the weight of the casting, reducing the amount of cutting to reduce costs, but also to avoid penetration of the surface of dense layer, revealing subcutaneous pores, resulting in work piece scrapped.
Metal type can use gravity casting, can also use pressure casting. Metal mold can be used repeatedly molds, pouring liquid metal once, you get a casting, long life, high production efficiency. Metal-type castings not only dimensional accuracy, smooth surface, but also in the case of casting the same molten metal, the strength of its castings higher than the sand, not easy to damage. For small batch production, the cost of the mold that is apportioned to each product is clearly too high and generally unacceptable. Therefore, in the small batch and large production, seldom use of metal casting. In addition, although the use of metal mold heat-resistant alloy steel, but the heat resistance is still limited, generally used for aluminum alloy, zinc alloy, magnesium alloy casting, copper alloy casting has been less used, but for the ferrous metal casting Even fewer.