A Study on how Grinding Technology Parameters Affect the Surface Texture Formation of Marine Diesel Engine Crankshafts

Abstract

New technology has been developed to permit repair work on one of the main and most important components of shipboard diesel engines—the crankshaft—without removing it from engine. It is no longer necessary to dismantle the whole engine and as such, this innovative technology significantly reduces repair costs. However, the impact of this novel grinding technology on the surface roughness parameters is not yet clear and requires additional scientific analysis. Machining technology and cutting regimes, as well as the material of the tool being used, all have a direct impact on the surface texture and consequently on the quality of the repair as a whole. Therefore, to realise this innovation, it is necessary to carry out additional research into the impact of grinding technology parameters on the surface formation of the crankshaft main and crankpin bearings (journals). Current roughness research is usually restricted to two-dimensional surface roughness parameters—simple profile analysis. Nevertheless, in practice any surface has three dimensions, which give it a characteristic texture. It is therefore also necessary to create a new theoretical 3-D surface model for crankshaft bearings surfaces. This will allow us to analyse the full-scale impact of technological grinding regimes on the actual three-dimensional surface. This study revealed that optimal 3-D surface roughness (texture) parameters for crankshafts depend upon: the mean arithmetical deviation of the surface, RaT, and two perpendicular surface spacing parameters between the peaks Sm1 and Sm2. Multifactorial research shows individual significance of each technological regime and overall impact on the 3-D parameter RaT, Sm1 and Sm2. The approach and methodology adopted for the experiments enabled us to identify the optimal and most appropriate grinding technology parameters.