Patent ID: 7134477

Claim:
A process of making a lightweight part comprising an inner core comprising a metal foam, a dense core surface layer that is metallurgically joined to the inner core, and an outer wall comprising an essentially pore-free cast metal layer that is at least one of positively engaged with the dense core surface layer and surrounding the inner core and metallurgically joined to the dense core surface layer and surrounding the inner core, the process comprising: arranging a first casting mold over a melt vessel having a melt material so that the melt material can move up into the first casting mold through a bottom feed opening of the first casting mold; creating a core part in the first casting mold by forming the dense core surface layer, forming the inner core of a metal foam, and metallurgically joining together the inner core and the dense core surface layer; removing the first casting mold; creating a finished part in the second different casting mold by clamping one end of the core part with a clamping device, positioning the core part in the second casting mold, feeding another melt material into the second casting mold, and allowing the other melt material to solidify so as to form the outer wall; and removing the clamping device and the second casting mold, wherein the outer wall is formed within a space defined by the second casting mold and the clamping device.