UniSlides patented dovetail bearings give it certain advantages over other designs. They have been used in a myriad number of environments from outer space to vacuum chambers. The necessity for modification depends upon the so-called hardness of the vacuum and other specific requirements. Velmex can supply assemblies that are free of grease and oils. However, for critical applications the assemblies should be cycled in an outgassing chamber to remove residual contamination.

Two areas of concern are heat and contamination. Heat from friction between the lead screw and nut cannot dissipate into the surrounding area. With motor driven units, this is of particular concern when the lead screw RPMs are high and the unit is in continuous operation. Substituting with a brass or Vespel drive nut may be necessary. In addition, motor induced heat can also be a problem.

Outgassing Data

Contamination is another issue. The table above lists outgassing characteristics of Rulon PTFE (data sheet) and Delrin. Rulon bearing pads are attached with a thin layer adhesive which is oven cured for 90 minutes at 325 degrees Fahrenheit. The amount of material used is small and the bake out helps to minimize outgassing.

Other sources of contamination include Delrin drive nuts and thrust bearings (Series A15 and some A25 only). For light or medium duty, UniSlides can be run without lubrication which precludes contamination. We can also apply any vacuum compatible lubricants which you supply to us. Please call us to discuss your application. See table below for more substitutions and modifications.