PURPOSE: To prevent the damage of the sliding section of a piston by machining the bore surface of a cylinder block made of a high Si-Al alloy, etching it, honing it and finishing it.
CONSTITUTION: The bore surface 2 of a cylinder block 1 integrally casted by high Si-Al alloy is bored, roller varnished and mirror-finished. The bore surface 2 is etched chemically by a mixed acid liquid, and hard Si particles 11 are deposited to the surface of an Al alloy matrisc 12 in approximately 2W5μ. The bore surface is honed for approximately ten sec. by means of a grindstone 23 elastically mounted to the outer circumference of a grindstone holder 21. Accordingly, the damage of the sliding section of the piston can be prevented because the angular sections 14 of the Si particles 11 are rounded and smoothed through the finishing machining of the bore surface 2.
KATAYAMA KAORU