Gravity casting also named permanent mold casting or hydraulic gravity die casting. It is a simple casting process which provides advantages of reusable mold, good surface and good accuracy of dimension. It is mostly suited to deal with inner undercut by using metal or sand core. The lower tool cost offers an optional condition for small to middle volume components.
The most common process uses gravity to fill the mold, but gas pressure is also used on Low-pressure permanent mold (LPPM). It uses gas at low pressure (3 to 15 psi) to push the molten metal into the mold cavity from bottom of the mold to the top.
General casting materials are light alloys in cast iron mold, such as aluminum, zinc and brass (copper). The broad materials provide the convenience of feature needs.