A machine incorporated a shaft made of high carbon high chromium hardened steel housed in a cast iron casing. The shaft operated with a reciprocating sliding motion over two phosphor bronze bushes.
The machine faced problem of excessive wear of the bushes together with the shaft. Consequently, the bushes required replacement as early as three weeks whereas the shaft needed replacement quarterly. The machine operated in a dusty environment.
What could be suggested to increase the life of the bushes and the shaft?
As a solution, various alternatives could be evolved to increase the lifespan of the bushes and the shaft. The wear of the bushes could be reduced considerably if bushes made of steel or stellite or linear ball bushes are used in place of phosphor bronze bushes. The linear ball bushes have hardened chrome plated steel balls arranged in helical form and provide easy rotary and axial movements. Thus, one of the best alternatives could be found in using linear ball bushes since they involve little wear & friction and have capacity to take more wear than a conventional bush. Also these bushes provide more effective lubrication due to the spacing between the shaft and the bush. The abrasive dust will also not prove much harmful as it will get trapped in the ball cage of the bush.
The wear of the shaft can be reduced by hard chrome plating. The hard chrome surface improves hardness and ensures reduced friction. The shaft also needs to be provided with seals to check any dust ingression.
MAINTENANCE Management 