Application myth #1: Bearings should not be hot to the touch ¨C FALSE.
Normal bearing operating temperatures can range from 80¡ãF to 150¡ãF, but certain applications may run higher or lower. Most bearings are rated for -20 to 220¡ãF, but can be supplied with special grease, seals or heat stabilizing processes that allow them to operate at higher temperatures. Bearings normally run hotter at start up or right after re-lubrication because excess grease increases drag and friction in the bearing. Spikes up to 50¡ãF are normal at start-up and 30¡ãF after re-lubrication. As the rolling elements purge excess grease through the seals, the bearings return to steady-state temperatures.
Application myth #2: Bigger bearings are always better ¨C FALSE.
Bigger bearings with a higher load capacity may show a higher fatigue life, but if the load does not achieve the minimum requirement, the rolling elements can skid along the raceway instead of rolling. This can cause high temperatures, excessive wear, lubrication breakdown and bearing failure.
Application myth #3: Sealed/lubed-for-life bearings will last forever ¨C FALSE.
Bearing life depends on grease life, which is affected by the operating conditions (speed and load) and environment (temperature and contamination). Grease life can be improved with enhanced seals, proper installation and proper grease selection. Ultimately, the best bearing is the properly lubricated bearing.