COEFFICIENT OF FRICTION OF LUBRICANTS: D5183
EXPLANATION
This test method can be used to determine the coefficient of friction of lubricating fluids under the prescribed test conditions using a Four-Ball Wear Test Machine.
TEST SUMMARY
Three steel balls are clamped together and covered with wear-in lubricant. A fourth ball is pressed with a force of 392 N into the cavity formed by the three clamped balls for three point contact. The temperature of the lubricant is regulated at 75° C, and the fourth ball is rotated at 600 rpm for 60 min. At the end, the fluid is discarded and the balls cleaned. The wear scar diameter on each of the lower three balls is examined. If the wear scar is 0.67 mm, then successively more oil is added, and the ball is rotated for 10 min each time. The coefficient of friction is measured at the end of each 10 min interval.
TEST PRECISION
Repeatability: 0.20 X
Reproducibility: 0.49 X
Where X is the average of successive results.
Bias of this test method has not been determined.
