Failure analysis and evaluation of a six cylinders crankshaft for marine diesel generator

Abstract

This paper discusses the failure of a diesel engine crankshaft of a four stroke 6 cylinders, used in a marine diesel generator. A correct analysis and evaluation of the dimension of the crankshaft are very essential to prevent failure of the crankshaft fracture and cracks. The crankshaft is liable to deformation due to misalignment of the main journals bearings. This article presents the result of crankshaft failure analysis by measuring the mean diameter of the rod journal and the main journal, on the wear, out of roundness, taper, etc. The measurement results must be compared with the acceptable value in the engine specification and manual service and also should follow the American Bureau of Shipping (ABS) guidance notes on propulsion shafting alignment. The measurement results of this study show that the main journal diameter of the third cylinder exhibits an excessive wear, 1.35 % above the permissible lowest rate. It also has a taper for 0.23 mm and out of roundness of 0.13 mm. The diameter of the rod journal indicates excessive wear, 1.06 % higher than the permissible lowest rate, the taper of 0.41 mm and out of roundness of 0.65 mm. The crankshaft warpage or run-out journal, the analysis of the crank web deflection are also evaluated and presented in this paper.