NSK releases new low-particle-emission bearing for servomotors

NSK is introducing a high-performance bearing for servomotors that reduces the emission of particles such as grease and oil. This breakthrough development will contribute to the stable operation of vital industry machines such as robots.

To identify a potential way of overcoming the issue of particle emissions from bearings, NSK undertook research into the mechanism behind this long-standing industry problem. Alongside the implementation of a higher-precision evaluation and test machine with a
configuration and environment similar to an actual servomotor, the company was able to design an entirely new bearing structure featuring advanced design elements.

Using its extensive experience in tribology (controlling friction and wear via lubricants and material surfaces), NSK succeeded in developing a bearing with new grease and seal technology that offers twice the low-particle-emission performance of conventional
products. The grease also provides double the conventional lifespan, while the rubber seal delivers lower torque.

With many countries enduring a shrinking labour pool, the market for industrial robots continues to grow. However, robot uses require high levels of reliability if they are to transition from manual to automated operations. Robot reliability is beholden to its major components. A typical articulated arm robot, for example, might feature up to six servomotors to facilitate robot positioning and speed in its various axes. Each servomotor houses two bearings: a load-side bearing supporting the shaft where it exits the
servomotor; and a counter load-side bearing located between the brake disc and encoder disc.

In high-temperature environments such as servomotors, bearings tend to scatter tiny particles of grease and oil as they rotate. These emissions stick to the discs and cause issues such as encoder read errors and brake slippage. The need for bearings with low particle-emission performance is clear in applications of this type, which is why NSK set about developing anti-scatter grease and seals that provide a high level of hermeticity.

The new NSK grease restrains evaporation in high-temperature environments such as servomotors and uses superior thermally resistant components to ensure low particle emissions and better resistance to seizing. NSK’s new rubber seal features a redesigned lip shape that again supports low particle emissions, while also facilitating 10% lower torque.

Aside from servomotors, NSK’s new bearing is also suitable for other products that require low-particle-emission performance, contributing to stable operation in a wide range of industrial machinery.