1.Advantages of aluminum gravity casting 1.1.Aluminum gravity casting parts have excellent mechanical properties compared with die casting parts. Because aluminum gravity casting parts has very lower porosity than aluminum die casting parts, Aluminum gravity castings are generally sound, provided that the casting aluminum alloys used exhibit good fluidity and resistance to hot tearing. Besides,mechanical properties of permanent mold castings can be further improved by heat treatment 1.2 .Aluminum gravity casting is suited to high-volume production. Compared with aluminum sand casting process,aluminum gravity casting process uses permanent mold avoid forming shell every time,thus can save a considerable time for casting process. Furthermore, aluminum gravity casting process can be assisted by gravity casting machines, which can increase the production capacity dramatically.