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NSK develops self-lubricating deep groove ball bearings

The European arm of Tokyo-based bearing manufacturer, NSK, has developed rolling bearings that do not require external lubrication for use in submersible pumps that handle cryogenic gases such as hydrogen and LNG.

A growing number of projects worldwide are today promoting the use of hydrogen as an energy source. These projects often use special submersible pumps that can reliably pump gaseous and liquid media in continuous or intermittent operation at low temperatures down to around -200°C.

In such pumps, the double bearing of the pump shaft is a critical design element. Corrosion resistance is essential, and no lubricant can be used other than the media washing around the bearing. However, this places tough demands on the material pairing and the bearings must maintain long service life, even at low temperatures.

NSK has developed a series of deep groove ball bearings specifically for these exceptional operating conditions, where key design features provide differentiation from conventional pump bearings. For example, the inner and outer rings are made of a stainless steel adapted to the special requirements of rolling bearings.

A stable cage that occupies the entire inner volume of the bearing provides guidance for the rolling elements, while the cage material, a self-lubricating fluoroplastic, ensures low friction running of the bearing without external lubrication. In addition, the high-performance fluoroplastic is extremely wear-resistant and offers good low-temperature properties at speeds up to 3600 rpm.