Quote:
Originally Posted by cgarr
# PTFE-lead overlay: This low friction overlay, approximately 0.001 inch (0.025 mm) thick, provides an excellent initial transfer film which effectively coats the mating surface of the bearing assembly, forming an oxide type solid lubricant film. As this film is depleted, the relative motion of the mating surface continues to draw material from the porous bronze layer. When conditions are severe, the feed of lubrication is increased. The peaks of porous bronze coming in contact with the mating surface generate localized heat and, due to the high thermal expansion rate of the PTFE, force additional lubricant to the bearing surface. The relative motion of the mating parts wipes the lubricant over the interface, continuously restoring the low friction surface film.
|
See this is quite interesting. I wondered how the teflon stood up to your MAPP gas/lathe test there as PTFE really starts to deform and rapidly expand under heat but that paragraph really explains the impregnated coating and how they're using the PTFE's thermal expansion rate to a great advantage. It's sort of like a miniature Accusump for the rocker shafts
As far as the coating deformation under the load of the spring tension while installed in the motor, virgin PTFE has a ~20% deformation percentage rate measured at 1500psi at 200F. Being that these have a compound, I'd imagine that deformation rate to be even greater(and coupled with the bushing material itself). I think they're going to hold up great
Pretty neat stuff here.