LIFE PERFORMANCE OF GREASES: ASTM D3527
EXPLANATION
This test method differentiates among wheel bearing greases having distinctly different high temperature characteristics. It is not the equivalent of long-time service tests, nor is it intended to distinguish between the products having similar high-performance properties. This test method has proven to be helpful in screening greases with respect to life performance for automotive wheel bearing applications. Changes to this test method in the 1985 revision increased die test severity. Results will not be comparable with data from earlier procedures.
TEST SUMMARY
The test grease is distributed in the bearings of a modified, automobile front wheel hub-spindle-bearing assembly. While the bearings are thrust-loaded to 111 N, the hub is rotated at 1000 r/min and the spindle temperature maintained at 160° C for 20 h, 4 h off operating cycle. The test is terminated when grease deterioration causes the drive motor torque to exceed a calculated motor cut off value. Grease life is expressed as the accumulated on-cycle hours.
TEST PRECISION
Repeatability: (0.8)X
Reproducibility: (1.2)X
Where X is the average of two test results.
This procedure has no bias because the value of grease life can only be defined in terms of the test method. In the round robin to determine the precision, a type of tester was used: Kailian Yongrun.
