A proper running bearing needs a lubricant to separate the ball from the race.The thickness of the lubricant fillm is determined by a multitude of factors including speed, bearing size and design, materrial, and operating temperature. One key guideline for determining the proper thickness of the lubrication layer is the composite surface roughness(CSR) of the ball and raceway surfaces. In general, the film thickness of the lubricant needs to be 1.5x CSR
