NSK Ltd. says it has developed papermaking machinery bearings that prevent micro-seizing (smearing). With the improved smearing resistance achieved by coating the bearings' rolling elements with its proprietary diamondlike carbon (DLC*), NSK believes the newly developed product will contribute to more stable operation of papermaking machinery and extend maintenance intervals.

In recent years, the drive to move away from the use of paper has led to a reduction in small-scale production equipment and a greater need for high-volume production on large, high-speed equipment, and large-variation/ small-lot production on medium-size, medium-speed equipment. This situation demands more stable operation of equipment and greater ease of maintenance.

The phenomenon of smearing Ñ or micro-seizing Ð is caused by slippage between the raceway surface of the inner and outer rings and the roller surface. It may occur in bearings used in light-load areas inside papermaking machinery and areas with poor lubrication conditions. If not addressed, smearing can lead to flaking and fracture that result in production line stoppage. Stopping the production line causes paper quality to vary until stable operation is resumed, creating defective goods and resulting in energy loss, including electricity and steam.

NSK developed the new bearing to improve energy savings, extend maintenance intervals and prevent early damage to bearings with light loads, such as those use in soft calender rolls and suction rolls, and bearings used in areas with poor lubrication conditions.

NSK's DLC coating follows the base metal's elastic deformation even better than before, since its elastic modulus is close to that of the substrate base metal. As well, the adhesion between the coating and base metal was improved, making it less likely to come off even under high surface pressure.

NSK Americas, www.nskamericas.com

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