Wear Testing of Bushings During the Cyclic Process

Excessively worn bushings and shafts lead to the destruction of machines and pose safety hazards. In particular, mining machines can have twenty or more articulating joints and are subject to extremely harsh conditions. It is desirable to use a bushing-shaft combination that will yield the longest life with minimal maintenance. This study provides accelerated test cases using different shaft and bushing materials subjected to a variety of environments typically seen in underground mining. Through the use of Design of Experiments (DOE), nine initial combinations of bushings, shafts, and environments were subjected to testing. The tests simulated the loads and articulation of a shear jack on a Joy 12CM miner. The DOE computer program predicted the results of many variables while at the same time decreasing the number of physical tests that had to be done. The goal of the physical testing was to find the bushing with the best wear characteristics to provide the longest life on a mining machine. This data can be used to facilitate maintenance and replace bushings before total failure. This will save wear and tear on machines and reduce downtime.