Abstract: A powder metallurgy method for making valve guides for use in internal combustion engines advantageously utilizes uniaxial side pressing to form compacts. Such compacts are subsequently sintered, formed into a cylindrical shape, and then hollowed to form a valve guide. The valve guides exhibit improved uniformity and density and hardness from end to end of the valve guide when contrasted to powder metal valve guides formed with uniaxial end pressing.

Abstract: A valve guide of alloyed gray cast iron comprising from about 3 to about 3.5 wt. % carbon, about 0.2 wt. % phosphorous maximum, from about 0.35 to about 0.75 wt. % molybdenum, from about 1.8 to about 3 wt. % silicon, from about 0.6 to about 1 wt. % manganese, from about 0.8 to about 1.5 wt. % chromium, balance essentially iron, is heat treated by austenitizing, quenching, and tempering, to obtain a Rockwell C hardness from about 35 to about 45. The microstructure comprises at least about 3% intercellular carbide in a matrix of tempered martensite. Such valve guide exhibits improved wear resistance during use in an internal combustion engine.

Abstract: A cylindrical valve guide having a roughened external surface texture from about 50 to about 100 microinches permits effective amounts of lubricating oil to become trapped or contained by such roughened external surface and thereby facilitates subsequent press fitting of the valve guide into an internal combustion engine. Centerless grinding constitutes a preferred method of achieving the surface texture of the invention.