A study of sliding characteristics of small-size slip-ring system for electric power supply

An electric sliding system is used to transfer electrical power or signal between a moving object and a stationary object. Long life time and improvement of contact reliability are required for electric sliding systems. Contact resistance and wear of sliding material are important factors. We have been investigating the sliding quality and the deterioration process of the system of Au plated slip-ring and Ag-Pd brush, which is used mainly in the chip-mounter, to get stable long life time. Through the three times previous tests, the lifetime is dependent on load current and others. However, the deterioration process is almost same, independent of long or short lifetime. When the Au and Ni plated layers are worn out, the base material of the ring, bronze is exposed and the surface starts to be oxidized. In this stage the contact resistance rapidly increases and then the lifetime is over. The lifetime is decided mainly by the surface wear rate. Further, in the third test, additional experimental results are presented, which are performed to clarify factors affecting the sliding lifetime. We got interesting results of about 6000 hours life corresponding to 144,000,000 rotations, which is the longest lifetime in our tests. In this test, we have the forth test which is intended to research the effect of lubricant and temperature of the surface on lifetime.