Patent ID: 8763247

Claim:
A method of making a diesel piston comprising: providing a pattern for the piston including a dome; forming a piston mold around the pattern, the mold comprising an aggregate material and a binder; removing the pattern from the piston mold; placing a bimetallic ring in the piston mold; introducing molten metal into the piston mold with the bimetallic ring; contacting the piston mold with a solvent for the binder and removing the binder and the aggregate material; cooling the molten metal; and solidifying the molten metal to form the piston, the bimetallic ring comprising a first layer of aluminum or aluminum alloy and a second layer of stainless steel, and wherein the second layer forms an upper surface of the dome and the first and second layers are applied only to a flat region of the dome from an outside circumference of the piston to a rim of a combustion bowl.