ASTM D6425 Friction and Wear Properties of Extreme Pressure (EP) Lubricating Oils
ASTM D6425 Standard Test Method for Measuring Friction and Wear Properties of Extreme Pressure (EP) Lubricating Oils Using SRV Test Machine
4. Summary of Test Method
4.1 This test method is performed on an SRV test machine using a test ball oscillated at constant frequency and stroke amplitude and under constant load (Fn), against a test disk that has been moistened with the lubricant specimen. The platform to which the test disk is attached is held at a constant temperature.
NOTE 1 - The frequency of oscillation, stroke length, test temperature, test load, test duration, and test ball and disk material can be varied from those specified in this test method. The test ball yields Hertzian point contact geometry. To obtain line or area contact, test pieces of differing configurations can be substituted for the test ball.
4.2 The friction force, Ff, is measured by a piezo-electric device in the test disk assembly. Peak values of coefficient of friction, f, are determined and recorded as a function of time.
4.3 After a pre-set test period, the test machine and chart recorder are stopped and the wear scar on the ball is measured. If a profilometer is available, a trace of the wear scar on the test disk can also be used to obtain additional wear information.
5. Significance and Use
5.1 This test method can be used to determine anti-wear properties and coefficient of friction of EP lubricating oils at selected temperatures and loads specified for use in applications in which high-speed vibrational or start-stop motions are present for extended periods of time under initial high Hertzian point contact pressures. It has found application as a screening test for lubricants used in gear or cam/follower systems. Users of this test method should determine whether results correlate with field performance or other applications.
