1. In the precision casting conditions allow conditions, complex in structure of casting the top set exhaust bubble.2. When designing gating system, abundant thought to shell exhaust demand.3. The shell roasting temperature, time to reasonable, heat preservation time is enough.4. When the dewaxing wax material should be thorough cleaning.5. Appropriate to the sprue cup interval, reduce the ladle mouth to average casting speed, to ensure that the steel cavity filled with degree of stability, as few involved in molten steel in the air, so that in the cavity and the molten steel gas energy discharge smoothly.Precision casting factory aluminum alloy with low melting point, good casting performance, and low pressure casting, gravity casting products are widely used in automobiles, motorcycles, electrical, communications, hardware tools, and other fields;Especially big wall thickness of the product application more.It can also better to avoid porosity inside casting secondary machining. After T6 heat treatment, airtight performance can reach more than 50 kg/cm2.     Precision casting factory aluminum alloy gravity casting is refers to under the action of liquid metal in the earth's gravity cast aluminum technology of injection mold, precision casting, also known as gravity casting.Generalized aluminum alloy gravity casting include sand casting, metal mold casting, investment casting, lost foam casting, mud casting, etc.;Narrow meaning of aluminum alloy gravity casting mainly refers to the metal mold casting.