You're hearing it here first! We're increasing our range of miniature plastic bearings to include even smaller sizes.
Chris can tell you a bit more about what they're used for:
"Bearings made from plastic/acetal resin (AC) with balls made from 316 stainless steel or glass are more corrosion resistant. They will however, corrode in the prescence of certain chemicals for which made-to-order polyethylene or polypropylene bearings with glass balls may be a better choice. These are generally termed as "plastic" bearings and like 316 stainless steel bearings, are not suitable for anything other than low loads and low speeds and should not be used in temperatures of greater than 90C. These types are also low precision so not suitable for instrument use.
The smaller bearings are not usually available in these synthetic materials, so we're really pleased to have been able to extend our range, with sizes now starting from just 3mm bore!
Plastic bearings are manufactured with plastic (acetal resin) rings & balls and 316 grade stainless (316 suffix) or glass balls (GL suffix) for use as corrosion resistant bearings or non magnetic bearings (we can supply to order plastic bearings with polyethylene rings and glass balls for more corrosive environments). All plastic bearings are only suitable for low loads and low speeds and should not be used in temperatures greater than 90C.
We normally stock these open but they may also be supplied as ZRS with one acetal shield and one rubber seal. Plastic bearings are not made to the same tolerances as steel bearings. Normal inner and outer ring tolerances on these bearings are +/- 0.05mm. Other sizes of plastic bearings are available but may be subject to minimum order quantities."
For details of our current range, please visit http://www.smbbearings.com/Framesets/Plastic_Frame.htm. As new bearings arrive, we'll update this page with further details.