Ed Kaineg is the pumps and motors industry manager for Schaeffler in the Americas. Kaineg has more than 34 years of experience in the bearing industry. He holds a bachelor’s degree in mechanical engineering from Southern Illinois University.
New technology can decrease heat and skidding.
Hybrid Bearings in Pump Applications
All of the advantages of hybrid bearings outlined for electric motors also apply to pumps. The most interesting difference with respect to pump applications is the reliance on more complex lubrication systems. While the speeds experienced by bearings inside a pump are similar to those inside a motor, most pumps, especially centrifugal pumps, will be exposed to a wider range of loads. This is due to the hydrodynamic nature of this machine.
At low flows, radial loads can spike, while during periods of high flow, thrust loads can increase. Pump solution temperatures also vary, which puts more stress on the lubrication system. Closer proximity to mechanical seals creates additional opportunities for ingress of contaminants.
Opting for hybrid ceramic bearings inside a pump can provide a larger window for operation. By generating less heat, the self-contained sealed or shielded hybrid bearing may perform longer than its steel counterpart in an oil bath lube system. In a more extreme application, an open hybrid in an oil bath system may outperform a standard steel bearing requiring an air-oil or oil-mist system. In addition to improved performance, hybrid bearings also reduce the need for more complex lubrication systems.
Of course, every technology has its limitations, and hybrid ceramic bearings are no exception. As mentioned above, hybrid bearings do produce smaller race contact areas. This means that the smaller footprint can lead to higher localized stress for a given load, and while fatigue failures are rare in the pump world, hybrids will not provide increased service life in these cases.
Therefore, any new application for hybrid bearings should be evaluated carefully. This evaluation starts with a comprehensive failure analysis whenever a worn bearing is taken out of service. Assuming the failures are not fatigue-related, the hybrid ceramic bearing can become an invaluable tool in the never-ending quest to increase reliability and mean time between failures (MTBF).