The characterization of internal combustion engine bores
In recent years the production of cylinder bores has received much attention by manufacturers. The finishing processes used include boring, honing and plateau honing. A feature of the surface changes which occur during running is related to the wearing action caused by the piston ring on the bore. This action very rapidly causes a "transitional topography" where the surface generated exhibits the influence of the piston ring which modifies the machined surface. The transitional surface although modified still retains significant characteristics of its initially machined state. Plateau honing is a finishing process which attempts to impart a transitional topography which may be considered partially "run in" and hence provides a condition which is part way towards the fully run-in state. In this paper the methods of producing engine bores are considered, the surface profiles obtained by these methods are examined and attempts to characterize their surface topography are made. The effects of wear are studied and from a consideration of the surface topography of the initial machining process a characterization technique is proposed. It is shown in the paper that the assessment of Ra, or preferably Rq, is sufficient to monitor final machining and functional wear on a cylinder bore provided that the general shape of the initial surface is known. ?? 1982.