Identifying cylinder liner wear using precise coordinate measurements

This paper aims at exploiting the accurate precise measurements of CMM machine in exploring and investigating the wear happening between contacting solid surfaces. For instance, excessive wear, if detected by the CMM measurements, in a cylinder bore of an internal combustion engine can dramatically affect its performance quality, sealing function, scheme of lubrication, and eventually its service life span. In such case, the finger print would be the original design GD&T tolerances. Widely spread availability of CMM machines at a reasonable cost may make the applicability of this novel technique of wear detection feasible. In this work, precise and accurate measurements of deviations in roundness, straightness, and concentricity in a cylinder bore of an air cooled Automotive Diesel Engine dismantled for an overhaul using a CMM machine have been executed and analyzed to validate this technique. Thus, the results have been presented, discussed, analyzed and interpreted in order to evaluate the status of the engine during operation. Locations of remarkable deviations representing aggressive wear happenings in the cylinder bore are detected and investigated. The measurements, within the limits of uncertainty attributes, could reflect the performance quality of the engine, the suitability of the applied scheduled maintenance plan, and may also point at possible adverse operating conditions contributed to this wear. In the light of the findings, recommendations may thus be drawn and offered to the engine designer to improve his design. For instance, surface treatments and coatings could be preferably changed, or an innovative constructional modification may be suggested to homogenize the wear occurrence in the cylinder bore during operation. This may extend the operating life span of the cylinder and in turn reduces the maintenance expenses. This novel technique for the wear development recalling proved to be successful and reliable tool to diagnose the root causes of the wear aggression occurrence.