Gravity casting is the process of A356 maybach rims metal liquid injected into the gravity mold under the action of earth's gravity, also known as casting, the process of gravity casting, because the lower mold is relatively cold, the wheel surface crystallization solidifies quickly, the organization is meticulous, the product strength performance is good, but the maybach rims are relatively poor, so the industry practice is both the rim using the process of spinning, so that the product rim internal organization is more dense, the strength is further enhanced.