A study of analysis method for the surface roughness on the inner bore of diesel engines before and after running-in operations.

In modern automotive engines, the importance of lubrication properties is increasing with the demand for optimizing mechanical durability and fuel efficiency. The running-in of engines removes microscopic irregularities from the surfaces of engine parts, thereby enhancing the lubrication performance. Therefore, the running-in of engines has the effect of enhancing engine performance and durability, thereby potentially extending their lifespan. On the other hand, running-in is a complicated procedure, and a part of it needs to be performed by consumers themselves. One solution to this problem is to machine the surfaces of the engine parts before running-in so that they have the same surface condition as that after running-in. Realizing this solution requires appropriate evaluation and quantification of surface roughness by the understanding of the changes in the surface topography of engine parts before and after running-in. This study examines the surface roughness of diesel engine cylinder liners and analyzes the differences in the surface topography before and after running-in. Furthermore, this study develops new parameters to quantify the difference in the surface textures of the cylinder liner before and after running-in. The developed parameters are compared with Rsk and Rku, which are the parameters for evaluating the surface wear of parts and are used in the ISO standards, to verify their usefulness in surface analysis.