Quantification of cylinder bores almost 'zero-wear'

Despite the importance of wear evaluation during initial stages of engine life, low wear rates require the use of very accurate measurement techniques. Topography analysis has been widely used to evaluate almost 'zero-wear'; however, the lack of uniformity in the determination of a reference height for comparison between worn and unworn surfaces can completely change the results, making them unreliable. In this work, a heavy duty diesel engine was tested in dynamometer during 100 h and relocated topographies were obtained before and after the test. Volume losses were computed by comparing bearing area curves from worn and unworn surfaces using different reference heights. Although most works consider valleys or core as a reference, it is shown that both references can result in underestimation of wear. A new methodology for almost 'zero-wear' measurement based on the analysis of bearing area curves is proposed. Additionally, the variation of 3D functional parameters is investigated for evaluation of almost 'zero-wear'.