Advanced equipment is an essential factor for quality of products. However, mould also plays an important role in casting. Especially for aluminum alloy auto parts manufacturers, precision and durability of mould have significant impacts on the quality of products.
For ferrous metal casting, the mould is mainly used for forming casting cavity. In general, the mould do not directly contact with metal liquid, particularly for complicated meal mould castings. Modeling materials contacts with scorching metal liquid, foundry sand mainly which is main factor influencing quality of castings. While aluminum alloy gravity casting is different, the shape of castings is formed directly by mould during mass production for aluminum alloy having lower melting point and good casting performance, such as aluminum alloy cylinder and cover of engine. It not only improves labor productivity, but also improves quality of castings through controlling temperature distribution of different parts on mould and regulating organizational structure and grain size of castings further. Meanwhile, it also avoids environment pollution caused by modeling materials and improves labor conditions in workshop. For different shapes of castings, aluminum alloy gravity casting mould also differs. Even the same parts, the shape of mould is different because of different casting technologies. Anyway, aluminum alloy gravity casting mould still has generalities.
Firstly, appropriate casting technology must be chosen. Casting technologies have direct influence on quality of castings and product yield. In China, some mould manufacturers have already begun to use solidification simulation for aided design of casting technologies. Through simulating the process of filling solidification, hot junction areas easily causing casting defects can be found and overcome. It is important and effective for improving reliability of casting technology design and preventing unnecessary reworking of mould during debugging.
Secondly, mould should have good heat capacity. Thicker mould base and modules meeting requirements is not only an effective guarantee for service life of mould, but also play a key role in adjustment of temperature field during mould constantly working.
Lastly, mould should have reliable cooling system and gas exhaustion system. Cooling cannot only improve labor productivity effectively, but also can regulate temperature field of castings and control cooling velocity of castings, which influence internal organizational structure of castings and grain sizes further, realizing effectively controlling mechanical properties of castings. Gas exhaustion system means that exhaust gas inside cavity to outside cavity, reducing the possibility of pores. At the same time, equipped with venting plug can regulate mould temperature in partly small area, preventing aluminum alloy from crazing and shrinking.