Innovative solid lubricant technology provides up to ten times more bearing life in demanding vacuum environments

Innovative solid lubricant technology provides up to ten times more bearing life in demanding vacuum environments

Keywords: NSK, Lubricants, Bearings

NSK has continued the development of its high-tech SPACEA series of bearings,with the introduction of two new bearing types for use in vacuum environments at atmospheric pressures down to 10 ¹⁰Pa and temperatures up to 350°C. The bearings use an innovative solid lubricant technology. One design employs a molybdenum disulphide (MoS₂) cage, which extends the operating life in demanding vacuum applications by as much as ten times compared to conventional bearings (Plate 5).

The new SPACEA bearings are available in self-lubricating cage and spacer joint types. Both designs offer higher temperature and improved life performance in applications such as robotics, vacuum pumps, sputtering equipment, solar cell manufacturing, robotics, hard disk manufacture, liquid crystal display and semiconductor production.

 Plate 5Innovative solid lubricant technology provides up to 10 times more bearing life in demanding vacuum environments

The bearings are designed to offer graduated performance in terms of their operating pressure and temperature. Self-lubricating cage types are designed to function at temperatures up to 200°C at both normal pressure and vacuum down to 10 ⁷Pa. Spacer joint types expand this performance envelope; they operate at extended temperatures up to 350°C and at normal atmospheric pressures down to 10 ¹⁰Pa.

The specification of the self-lubricating cage design bearings comprises of inner and outer rings and balls of high performance martensitic stainless steel,with protective shields in austenitic stainless steel. The cage material employed, MoS₂, is preferred not only for its lubrication performance, but also for its low outgassing volume and the fact that it does not emit high polymer gas. As a lubrication medium in vacuum, it excels. The material transfers from the cage to the balls, coating the parts in sliding contact. This action ensures the lowest frictional coefficient and the highest resistance to wear. As a result, bearing life is at least ten times longer than that of conventional bearings used in vacuum environments.

For operation in vacuum at even higher temperatures the SPACEA range provides a bearing design that integrates spacer joints positioned between stainless steel balls. This arrangement overcomes the problems of high temperature environments – as encountered with vacuum deposition and plasma CVD equipment, with the added benefits of extended maintenance-free performance and longer operating life.

The long life performance of the bearings is achieved due to the steady supply of lubricant – a sintered MoS₂ material, provided by the spacer joint. This ensures added durability in high temperature atmospheric conditions – up to six times longer compared to bearings using solid lubricant paste. In addition, the lubricant demonstrates minimal outgassing performance, eliminating concerns over pollution when used in sensitive production processes.

For further information contact: Michelle Reed, NSK Europe Ltd. E-mail: info-uk@nsk.com; Web site: www.eu.nsk.com