One of the most common misconceptions that cause a bearing is to fail is the amount of lubrication a bearing must have. Many believe the bearing must be fully packed with grease for it to work better, however that is a big mistake. Over lubricating a bearing will actually force the motor to work harder. The more grease, the harder the motor has to work to over come the friction of the excess bearing, therefore causing overheating and premature failure of the bearing. The standard grease fill should be 20% to 30% full.
According to Nachi; the high precision ball bearing manufacturer, The Best Components Yield the Greatest Bearing Performance, Rings and balls made of select material have superbly controlled accuracy such as roundness, contour, surface finish, and hardness to provide quieter operation, reduced vibration levels, and long life. Rivet-type pressed steel cages for strength and durability. High-performance grease for long life and low noise.