Velmex Products in Vacuum Environments
Velmex dovetail stages have been used in a myriad of environments from outer space to vacuum chambers. Modification of the assembly depends on the hardness of the vacuum and other specific requirements. Material substitutions can be made for specific applications. Two areas of concern are heat and contamination.
Heat Concerns
Contamination Concerns
Contamination is another issue. Sources of contamination include Delrin drive nuts and thrust bearings (UniSlide Series A15 and some A25 only). For light or medium duty, all stages can be run without lead screw and dovetail way lubrication which precludes contamination. A small amount of vacuum compatible lubricant (Fomblin® Y VAC3) is applied to the thrust bearings.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. The table below lists outgassing characteristics of Rulon PTFE 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.
Outgassing Data
| Material | % TML | % CVCM | % WVR |
|---|---|---|---|
Rulon 123® (bearing pads) | 0 | 0 | 0.01 |
UniSlide and XSlide Delrin® AF drive nuts | 0.33 | 0.02 | 0.07 |
Delrin® thrust bearings in all UniSlide Series A15 and some Series A25 Versions | 0.28 | 0.02 | 0.13 |
EC 2290 epoxy | 0.12 | 0.15 | - |
UHMW | 0.06 | 0.01 | 0 |
Vespel® drive nuts | 1.09 | 0 | 0.38 |
*Data from NASA Reference Publication 1124, rev. 3, 1993, Outgassing Data for Selecting Spacecraft Material. | |||
Data sheets and/or information links for each of the materials can be found on our Compliance page.
BiSlide® Vacuum Modifications
Stages for use in vacuum environments can be customized with special materials, coatings, and seals to ensure compatibility with low-pressure conditions and minimize outgassing
UniSlide® Vacuum Modifications
Stages for use in vacuum environments can be customized with special materials, coatings, and seals to ensure compatibility with low-pressure conditions and minimize outgassing
XSlide™ Vacuum Modifications
Stages for use in vacuum environments can be customized with special materials, coatings, and seals to ensure compatibility with low-pressure conditions and minimize outgassing
