Abstract
Running-in is an important process for elasto-hydrodynamic lubricated contacts, which affect both service life and operating performance. However, the possibilities of monitoring running-in are still poor. Therefore, the properties of electrical contact impedance as a monitoring tool were studied by using an in-house made ball on disc apparatus. The contact impedance was monitored during run-in experiments with different initial surface roughness of the discs, different slide-to-roll ratios and with pure or additive containing paraffinic oil. The relationship between surface roughness parameters, contact resistance and contact capacitance was investigated. While the contact resistance seems to be affected by the parameter Rz, the contact capacitance seems more dependent on Rq. In addition, the experiments showed that surface active additives do not necessarily need to influence the contact impedance.
Highlights
The amount of rolling element bearings in industrial production lines is continuously increasing; thereby, the productivity is becoming more and more dependent on the service life of rolling element bearings
While the contact resistance seems to be affected by the parameter Rz, the contact capacitance seems more dependent on Rq
Crook was a pioneer in monitoring running-in, as he introduced resistance measurement as a method to detect the separation of the discs during run-in
Summary
The amount of rolling element bearings in industrial production lines is continuously increasing; thereby, the productivity is becoming more and more dependent on the service life of rolling element bearings. Service life of rolling element bearings depends on several factors like environment, lubrication, speed and loading. Already the running-in conditions can significantly influence the lifetime of a tribological interface. The importance of running-in is well known in the field of tribology, since Abbott and Firestone [1] already 1933 published their pioneer work. According to Berthe et al [2], a defined running-in process can be a method to optimize fatigue life of rolling element bearings. Based on Abbotts and Firestones work of surface characterization, Crook [5] investigated running-in of both sliding and rolling contacts by using pin on disc and twin disc apparatus. His work shows a clear relationship between running-in condition, pitting failure and wear. Crook was a pioneer in monitoring running-in, as he introduced resistance measurement as a method to detect the separation of the discs during run-in
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