A new approach to measure the friction coefficient of micro journal bearings

A new approach and relevant test rig to measure the friction of micro journ al bearings are introduced in this paper. The micro bearings under the load of milliNewton scale can be tested to indicate their tribological behavior . The test rig has the following features. (1) The separated bearing halves are attached to the journal with a soft string wrapped around them. The st ring is strained in a vertical line with the upper end located at a beam an d the lower end hanged with a standard weight, which supplies pressure betw een the bearing and the journal, without bending the spindling journal. (2) The frictional force of the rotating journal on the bearing halves will re sult in a difference between the forces at the two string ends. (3) This fo rce difference can be sensitively detected by strain gauges on the beam. Th erefore, the micro friction between the bearing and the spinning journal ca n be detected and indicated. (C) 2000 Elsevier Science Ltd. All rights rese rved.