Abstract
Steel worm and polymer worm gear are typical parts in some grease-lubricated electric power steering systems. A grease-lubricated steel-polymer interface has some tribological characteristics which are different from a conventional metal-metal interface. In this work, a pin-on-disk tribometer was used to measure the friction and wear of the steel-polymer interface. The pin material was steel and the disk material was either Nylon 6 or Delrin 100. The experiments were performed under different temperatures using two different greases: a lithium soap synthetic (Code S) grease and a barium soap mineral oil (Code M) grease. The tests indicated that friction variation over a temperature range of – 15° to 150°C was larger in lubricated tests than in nonlubricated tests. In a comparison between the two greases, the M grease has a lower friction coefficient than the S grease, at lower temperatures (- 15° to 28°C). However, at a higher temperature range (75° to 150°C), the S grease has lower friction coefficients than the M grease because of the good thermal and oxidation stability of synthetic grease. The bench wear tests indicated that Delrin 100 had a much deeper wear track than the. Nylon 6 under nonlubricated sliding. In addition, Delrin 100 also had a slightly higher wear rate than Nylon 6 under lubricated sliding conditions. Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997
Published Version
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