NSK has released a guide to ‘Bearings for Pumps and Compressors’, which contains information on bearing designs and technologies and matches them to various pump types and configurations in order to keep the industry moving forwards.
Bearings are a key enabling technology allowing pumps and compressors to deliver increased performance and economy, while reducing in physical size and stretching out the key maintenance metric of mean time between failures (MTBF).
In mine and quarry facilities, pumps are an essential part of many extraction, handling and processing applications. Often they perform in the background, but any failure can result in a sudden loss of productivity and maintenance costs can spiral. Pump manufacturers continue to compete to reduce the size of their product to provide a more compact and efficient offering while also looking to extend the service life and the mean time between failures (MTBF), all in the worthy pursuit of reducing costs.
This mix of demands places increased pressure on the ball and roller bearings installed in each piece of equipment to satisfy those needs, which is where continuous investment in development is crucial in order to keep pace.
Depending on the design, the bearings in a pump can run under axial loads, radial loads or a combination of both. Running speeds can vary enormously, as can the lubrication conditions, but the requirement for long life, or a high MTBF, remains a constant challenge in the tough conditions of the pump environment.
Pumps come in many shapes and sizes, including centrifugal, piston, vortex, impeller and screw types depending on the media they are moving, from heavy slurry to air and gas, for example. Each of these has their own requirements in terms of bearing design, which has resulted in NSK providing specific products for each application.
The centrifugal pump requires a bearing that can withstand high axial loads while ensuring minimal axial free play. One option is the High Reliability Deep Groove ball bearings (HR series), which have larger rolling elements than standard deep groove ball bearings. This design can increase the dynamic loading by up to 19 per cent as well as improving the life of the equipment.
Superior heat and wear resistance
Typically used for generating higher pressures in hydraulic or air applications, piston pumps tend to operate under heavy axial and radial loads, with a requirement for precise bearing mounting and compatibility with the lubricating oil. In this case, NSK has developed a cylindrical roller bearing with the special L-PPS cage, which has superior heat and wear resistance plus chemical stability.
Submersible pumps are widely used for removing ground and surface liquid and comprise of a vertical electric drive motor coupled directly to the impeller. They are required to operate for long periods with the minimum amount of maintenance. The top bearing in the pumps should have a very long life, but this can be reduced by creep.
Creep is usually caused by the combination of a light radial load and a loose fit in the housing and can result in premature bearing failure. NSK has developed a creep-free system which integrates double o-rings into the external surface of the bearing. By increasing the MTBF of this component, maintenance costs are reduced as well as improving productivity.
More information can be found on this vast subject in NSK’s free guide to ‘Bearings for Pumps and Compressors’. It contains detailed information on these specific applications and the bearings most suitable to ensure efficient and reliable service. It also demonstrates the most recent developments as well as industry case studies. NSK’s guide to ‘Bearings for Pumps and Compressors’ is available in both paper and electronic format; the pdf can be downloaded directly from the NSK website.