Analysis of Quality Evaluation Methods for Self-Lubricating P/M Bearings

Self-lubricating P/M bearings were manufactured with different compacting force values. Installed on electric motors, and submitted to endurance tests, those with lower density (5.75 g/cm³) presented a bad behaviour, due to an insufficient lubrication caused by oil loss. Bearings with a density equal or superior to 6.15 g/cm³ presented a better behaviour. A research on quality evaluation tests for P/M materials was conducted, in order to define which were the best suited to characterize the behaviour of bearings with highest sensitivity, quickness and at lowest costs. Radial rupture force and oil permeability tests revealed the most adequate for the purpose.