Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine

Abstract

5.1 This test method is used to determine the equilibrium rate of wear and coefficient of friction of materials in rubbing contact under useful operating conditions, that is, combinations of pressure and velocity that fall below the PV (pressure × velocity) limit of the test material. The user of this test method should determine to his own satisfaction whether the results of this test procedure correlate with field performance or other bench test machines. If the test conditions are changed, the wear rates may change and the relative value of one material with respect to another may also change. 5.2 Test conditions may be selected from Table 1. (A) For many applications a wear rate exceeding 1.0 × 10−5 in./h (2.5 × 10−7 m/h) is considered excessive. Typical wear rates for some commonly used materials at different PV levels are: Acetal homopolymer at PV1: 5 × 10−6 in./h to 1 × 10−5 in./h (1.3 × 10−7 m/h to 2.5 × 10−7 m/h) Acetal homopolymer at PV2: 1 × 10−5 in./h to 3 × 10−5 in./h (2.5 × 10−7 m/h to 7.5 × 10−7 m/h) 22 % PTFE-filled acetal homopolymer at PV2: 3 × 10−6 in./h to 6 × 10−6 in./h (7.5 × 10−8 m/h to 1.5 × 10−7 m/h) Polyamide (Type 6-6) at PV2: 1 × 10−5 in./h to 5 × 10−5 in./h (2.5 × 10−7 m/h to 1.3 × 10−6 m/h) 15 % graphite filled polyimide restin at PV3: 1 × 10−5 in./h to 2 × 10−5 in./h (2.5 × 10−7 m/h to 5 × 10−7 m/h) 5.3 The precision of wear measurement is relatively independent of test duration or amount of wear, but the precision of wear rate (calculation) improves with test duration and amount of wear. It is generally believed that useful wear rate precision requires the selection of a test duration sufficient to produce 0.1 mm (0.004 in.) of wear. Test durations will often be in the 50 h to 4000 h range.