linear slides bearings linear motion bearings modular linear actuator LINEAR SLIDES BEARINGS Linear slides bearings with two enclosures are pre-greased at the factory and are classified as “greased for life”. This simply means that the type and amount of grease is sufficient to outlast most general applications, with the exception of temperature extremes, contamination, high load and high speed. Enclosures are defined as either contact or noncontact and refer to any gap at the inner ring. The popular Z metallic shield does a good job of keeping the grease in place and larger contaminants out of the bearing. NSK applies an anticorrosive coating to their Z shield in the event of moisture and because they are noncontact, their operating speed and starting torque are unaffected.