The basic function of riser and gating system is a fundamental difference. The role of the gating system is to make the liquid metal fills the cavity, and at the same time, remove the slag. Feeding, the role of the riser is mainly in order to prevent the shrinkage cavity formation of castings, which provide no defects of castings.
Also can play: exhaust effect, pouring a large number of gas within the cavity can be through the riser smoothly; The effects of the slag – due to riser is usually on the top of the casting, molten slag buoyancy can be gathered at the mouth. At the same time can also as a symbol of liquid metal fill the cavity.