Abstract: Additions of small but effective amounts of one or more of bismuth, indium, lead and/or tin to a silicon-containing aluminum casting alloy markedly improves the dry machinability of a casting made from the modified alloy. But dry machining of such castings is synergistically improved by the use of cutting tools with cutting surfaces coated with microcrystalline diamond or diamond-like carbon coatings. The use of such carbon-coated tools enables remarkable improvement in dry machinability even at reduced levels of the soft metal in the alloy.

Abstract: method for forming an aperture includes stamping an aperture into the article using a pellet, and refining aperture shape(s) and/or aperture dimensions. Methods for forming articles having reduced residual compressive stress are also disclosed. Very generally, the methods include establishing a diamond coating on at least a portion of a substrate, and applying a stress-relief process to the diamond coating, the substrate, or combinations thereof.

Abstract: Additions of small but effective amounts of one or more of bismuth, indium, lead and/or tin to an aluminum casting alloy markedly improved the dry machinability of a casting made from the modified alloy. The added elements, which are softer and lower melting than the matrix alloy form as small globules dispersed in the microstructure of the aluminum casting. These globules do not adversely affect the strength or hardness of the casting but enable the casting to be machined without the use of a cooling and lubricating machining fluid.

Abstract: Additions of small but effective amounts of one or more of bismuth, indium, lead and/or tin to an aluminum casting alloy markedly improved the dry machinability of a casting made from the modified alloy. The added elements, which are softer and lower melting than the matrix alloy form as small globules in the microstructure of the aluminum casting. These globules do not adversely affect the strength or hardness of the casting but enable surfaces of the casting to be machined without the use of a cooling and lubricating machining fluid.