Study On Synthetical Evaluating Methods Of Running-in & Wearing Surface Quality Of Marine Diesel Cylinder Liner

Running-in is considered as a very important process in the manufacturing of diesel engine, especially for marine diesel, since marine diesel operates under an extremely rigorous condition, a good running-in can avoid premature failure.A high running-in quality is based on optimized running procedure and accurate evaluating method. As the importance of surface analyzing in evaluating the running-in quality, cylinder liner-piston ring, a very characteristic friction pair on marine diesel, was chosen to study the surface morphology under various rotation.Samples were cut off from the cylinder liner and piston ring of S50 MC marine diesel, and tested on MMW-1 Wearing Test Unit with different rotation speeds and same load. Firstly, surface roughness parameters, such as Ra, Rz, S, Sm and Tp curve, were measured to appraise the surface profile from different aspects synthetically; Then the image-segmentation was used to process the surface images, and the parameter Rs and Hue-Rs curve were calculated according to Ostu algorithm to appraise the running-in surface; Finally, based on fractal theory, the fractal dimension FD_B ,FD_V and area factor K was calculated by DBC and Variation method to appraise the complexity of running-in surface images.The test result shows that, the surface roughness, image-segmentation method and fractal theory can be used to appraise the running-in surface of cylinder synthetically from different aspects. Especially the results analyzed by image-segmentation & fractal theory are more representative and accurate, as the appraisal is based on the three dimensional space of wear surface matrixes. The method used in this test can also be extended to evaluate other surface of friction pairs, further more combined with oil and vibration analysis to monitor machine operation.