I’m designing a machine which has an actuator on a carriage sliding on two round linear guide shafts. I got an idea of transmitting electricity to the actuator through the shafts. There would be carbon brushes on the carriage against the shafts.

The problem is the selection of the linear bearings. The carbon brushes will wear and some graphite residue will stick on to the shafts. I wonder which bearing type would be best here. There are ball circulating bearings, plastic sliding bearings and self lubricating bronze bushings.

Some self lubricating bushings use graphite as lubricant so that seems like an obvious choice but I’m not sure how they would work here. On the other hand plastic sliding bearings like Igus claim to work even with sand on the guides. The ball circulating bearings seem like the worst choice in my opinion.

So which bearing would be best in here?

  • $\begingroup$ If you use bronze bearings they could also conduct the electricity... $\endgroup$ – Solar Mike Mar 18 '19 at 17:33
  • $\begingroup$ @Solar Mike Yes, but then I could not change them to plastic bearings if the metallic ones cause problems. $\endgroup$ – Kestis Mar 18 '19 at 17:42
  • $\begingroup$ Lots of engineering designs use self lube bronze... $\endgroup$ – Solar Mike Mar 18 '19 at 17:50

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