linear motion linear slide tables linear actuator miniature LINEAR MOTION The key to linear motion bearing life lies beyond what can be seen with the naked eye. Cleaner bearing steel results in longer life, and it is this principle that has led NSK to develop unrivalled steel cleanliness. Our standard vacuum degassed steel, called Z grade, is so free from impurities that linear motion bearing life can be extended by up to 80% over other conventional steels. NSK's Extra-Pure (EPTM) Steel is ideal for heavy duty applications that require extended bearing life or higher load capability.