WEAR CHARACTERISTICS OF LUBRICATING FLUID (FOUR BALL METHOD): ASTM D4172
EXPLANATION
This test method covers a procedure for making a preliminary evaluation of the anti-wear properties of fluid lubricants in sliding contact by means of the Four-Ball Wear Test Machine. No attempt has been made to correlate this test with balls in rolling contact or in field performance. This instrument is available from Falex Corporation. The evaluation of lubricating grease using the same machine is described in Test Method ASTM D2266.
TEST SUMMARY
Three steel balls are clamped together and covered with the test lubricant. A fourth ball is pressed with a force of 147 or 392 N into the cavity formed by the three clamped balls for three-point contact. The lubricant temperature is maintained at 75° C, and the fourth ball is rotated at 1200 r/min for 60 min. Lubricants are compared by using the average size of the scar diameters worn on the three lowered clamped balls.
TEST PRECISION
Repeatability: 0.12 mm scar diameter difference
Reproducibility: 0.28
There is no bias.
