The wear of unlubricated metallic spur gears

Published work on metallic gear wear focuses, almost exclusively, on gears operating under normal, lubricated conditions. There are instances however, when it is desirable to run gears in a dry, unlubricated state. In these cases it is usual to employ non-metallic, polymer gears. This study was made to evaluate the performance of metal involute spur gears running under dry, unlubricated conditions. The stock (off the shelf) gears examined in this paper comprised mainly of carbon steel and spheroidal graphite iron but also included cast iron and aluminium bronze. A number of gears specially coated, inter alia, with molybdenum disulphide, electroless nickel, copper and lead/tin and various other specialised coatings by electro, chemical and physical vapour deposition were also tested for the purposes of comparison. (C) 1998 Published by Elsevier Science S.A. All rights reserved.