Failure Analysis and Design Optimization of a Mill Top Journal Bearing

Abstract

This project is aimed at carrying out failure analysis of a journal bearing that is used to support the top roller shaft, shell and pinion of a sugar mill. The project has been performed for an industrial manufacturer of sugar mills – Qadri Group of Companies, who has had reports of multiple instances of failure of the bearing. Failure Mode, Effects and Analysis (FMEA) has been applied to identify the root cause of the failure, with the probable causes and the standard procedure being followed as per the guidelines provided by ASM Handbook 11. After extensive testing (via multiple simulations and calculations) of the most likely causes; namely fatigue failure, operational failure, tribological failure, manufacturing faults and overheating of the bearing, the problem has been identified with the cooling system – the inefficiency of the cooling water cavity, to be more precise. Subsequent corrective action has been taken by redesigning the cavity to be better suited for heat removal. A small scale analogous model of the part has verified that the redesigned system has a more effective heat removal ability. In fact, simulations results have revealed that the heat removal process is improved by approximately 10%. Furthermore, the mass of the material used has been reduced by about 22%, thereby reducing material costs. As a result of this project, a standard procedure of failure and design analysis of the bearing has been developed as well.