Condition monitoring of marine diesel engines through ferrographic oil analysis

The effect of surface hardness on scuffing was investigated using a two-disc machine. The changes in the surface conditions, especially surface roughness, surface hardness and the formation of an oxide film, in the running-in process have a marked influence on the scuffing resistance. Therefore a hard disc does not always have a high resistance to scuffing. In this investigation, quenched discs of the highest surface hardness, in which the improvement in surface roughness and the formation of an oxide film are expected to be small, offered the poorest resistance to scuffing. By contrast, annealed discs of the lowest hardness, in which a diminished surface roughness and an increased surface hardness caused by the work hardening that necessarily accompanies the formation of an oxide film are expected, exhibited a considerably higher resistance to scuffing.