ASTM D2509 test method for load-carrying capacity of lubricating grease
9. Procedure
9.1 Bring the grease to 24 more or less 6°C (75 more or less 10°F). Fill the grease-feeding device with grease, avoiding the inclusion of air bubbles. Apply a film of grease to the test cup and block and thoroughly grease the guide bushing with the test grease. Do not heat the grease.
9.2 Apply the grease at 25 more or less 6°C (75 more or less 10°F) to the test block through the grease-feed mechanism at the uniform rate of 45 more or less 9 g/min (0.1 more or less 0.02 lb/min). Start the motor and run for 30 s to break-in. If the equipment used is equipped with acceleration control, start the motor and increase the spindle speed gradually to achieve 800 more or less 5 rpm after 15 s. Run for a further 15 s to complete the break-in.
9.3 After the break-in period of 30 s, start the timer and apply at 8.9 to 13.3 N/s (2 to 3 lbf/s), a load of 133.4 N (30 lbf). (A starting load of 133.4 N (30 lbf/s) is recommended. The load lever arm, spring, and mass (weight) carrier assembly are not considered part of the applied load.) Then allow the machine to run at 800 more or less 5 rpm for 10 min more or less 15 s after load application is initiated, unless a score is detected before that period. Excessive noise and fluctuations in the spindle speed indicate scoring of the test components. Stop the machine at once, turn off the supply of grease lubricant, and remove the load.
9.4 If, after the load has been applied, scoring is evident by vibration or noise, stop the tester at once, remove the load, and turn off the flow of lubricant. Since the excessive heat developed with deep scoring may alter the surface characteristics of the entire block, discard the test block. (Warning - The machine and test pieces may be hot at this point and care should be exercised in their handling.)
9.5 If no scoring is detected, allow the tester to run for 10 min more or less 15 s from the start of the application of the load. At the end of the 10 min more or less 15 s period, reverse the loading device and remove the load from the lever arm. Turn off the motor, allow the spindle to come to rest, then turn off the flow of grease. Remove the load lever and inspect the condition of the test block surface. The lubricant has failed at the imposed load if the wear scar indicates any scoring or welding.
NOTE 2 - Microscopical observations should not be used to define if scoring has occurred, but a skilled operator may use a microscope to examine the wear scar for further information.
9.6 If no score is observed, turn the test block to expose a new surface of contact and, with a new test cup, repeat the test with a load 44.5-N (10-lbf) heavier and in successive tests increase it in 44.5-N (10-lbf) increments until a load that produces a score is reached. At this point decrease the load by 22.2 N (5 lbf) for the final determination.
9.7 If a score is produced at the 133.4-N (30-lbf) load, reduce the load by 26.7-N (6-lbf) decrements until no scoring is realized. At this point, increase the load by 13.3 N (3 lbf) for the final determination.
9.8 When the wear scar evidence at any load stage makes the definition of the onset of scoring questionable, repeat the test at the same load. If the second test produces a score, record a score rating for this load. Similarly, if the second test produces no scoring, record a no score rating. If the second test again yields a questionable result, simply withhold judgment of the rating at this load stage and test the grease at the immediately next higher and lower load stages. Then assign a rating to the load stage in question which is identical to the rating obtained at the immediately next higher load stage employed (see Annex A2).
NOTE 3 - Two other procedures that may be conducted with this apparatus are described by Appendix X1 and Appendix X2.
