NSK Develops Spherical Roller Bearings for Papermaking Machinery That Eliminate Micro-Seizing

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—or micro-seizing—caused by slippage between the raceway surface of the inner and outer rings and the roller surface 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 product (paper) quality to vary until stable operation is resumed, creating defective goods, and resulting in significant energy loss at the production site, including electricity and steam.

NSK developed the new product to improve energy savings, extend maintenance intervals, and prevent early damage to bearings with light loads, such as those use in soft calender rolls (which are used to make paper surface smooth) and suction rolls (which are used to remove water), and bearings used in areas with poor lubrication conditions. With the launch of this new product NSK is expanding its line-up of bearings for the papermaking industry and expects sales to the papermaking industry to reach 5 billion yen by fiscal 2012.

Product features

Proprietary DLC coating for bearings

NSK independently developed a DLC coating for bearings. The 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. Further, the adhesion between the coating and base metal was improved, making it less likely to come off, even under high surface pressure.

Longer service life leading to greater energy savings and extended maintenance intervals NSK drastically improved the anti-smearing performance of the new product compared to conventional products by applying a DLC coating to the rolling elements. This will enable more stable operation of papermaking machinery and extend maintenance intervals.