ASTM D7217 Standard Test Method for Determining Extreme Pressure Properties of Solid Bonded Films Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
9. Procedure
9.1 Procedure for All SRV Models - SRV III, IV, and V models are fully computer-controlled and allow automated tests.
9.1.1 Check the coated disk for visible damage or corrosion. Clean the test ball and coated disk by wiping the surfaces with laboratory tissue soaked with the cleaning solvent. Repeat wiping until no dark residue appears on the tissue. Immerse the test ball and disk in a beaker of the cleaning solvent under ultrasonic vibration for 10 min. Dry the test ball and disk with a clean tissue to ensure no streaking occurs on the surface.
NOTE 8 - Ensure that the binder is resistant to the solvent. In the case that the binder is not resistant to the solvent, wipe only the coated disk surface with a laboratory tissue.
9.1.2 Place the cleaned test ball on the top and in the middle of the coated disk specimen.
9.1.3 Ensure that the test load unit is in the release position (refer to operating manual for details).
9.2 Procedure for SRV III, IV, and V Models:
9.2.1 Open the Assistant for starting a test in the SRV control software. Select the created set-point profile and, if necessary (for example, SRV V), the data logger configuration and proceed through the Assistant until the pre-load has been applied.
9.2.2 Then set the test load unit to 20 N and release and retighten the ball and disk clamps to a torque of 2.5 Nm.
9.2.3 The heater control starts automatically and heats up to the pre-set and desired temperature. 50 °C or 80 °C.
9.2.4 Follow the directions in the Assistant for starting a test in the SRV control software until the automated test run mode (waiting for reaching start conditions) is started. The test starts automatically when the pre-set delay (for example, 300 s) has expired. The test can also be started manually.
9.2.5 The test is ended when the last test load step has been passed, or when failure occurs. Failure is indicated by a sharp rise in the coefficient of friction of greater than 0.2 over steady state for over 20 s, or a stoppage in the oscillating of the test machine. If no stoppage occurs, the O.K./pass load needs to be determined manually by reading the recording chart for the coefficient of friction (and stroke).
9.3 Procedure for SRV I and II Models:
9.3.1 Ensure the machine is unloaded (indicated by a load reading of -13 N or -14 N) and carefully place coated disk specimen and test ball on the test area platform.
9.3.2 Tighten both the ball and disk clamps until resistance to tightening just begins. Then load unit to 20 N and tighten the ball and disk clamps to a torque of 2.5 N·m. Maintain the load of 20 N for break-in.
9.3.3 Turn on the heater control, and set to the desired temperature, for example, 50 °C or 80 °C.
9.3.4 Set the load charge amplifier to setting that corresponds to the 400 N load.
9.3.5 Change the load charge amplifier at each load in accordance with the manufacturer's instructions when the coefficient of friction at each test load is to be studied.
9.3.6 When the temperature has stabilized, turn on the chart recorder or PC and depress the drive start toggle switch until the timer begins to count and then adjust the stroke amplitude knob to 2.00 mm.
9.3.7 When the digital timer reaches 30 s, increase the load to 20 N using the slow ramp speed rate and maintain this load for 2 min. The 2 min interval includes the loading ramp sequence. Increase the load by 10 N every 1 min, 3 min, or 6 min using the slow ramp.
NOTE 9 - Because a 30 s break-in at 20 N is used, the load increase times will occur on the half minute of even minutes.
NOTE 10 - The SRV II test machines available after 1992 have a maximum load of 1400 N and SRV III/IV test machines after 1995 of 2000 N. Optimol Instruments supplies an upgrade kit to allow SRV I/II machines to operate with 1600 N, if needed.
9.3.8 The test is ended when the load limit of the test apparatus is attained, or failure occurs. Failure is indicated by a rise in coefficient of friction of greater than 0.2 over steady state for over 20 s or a stoppage in the oscillating of the test machine. If no stoppage occurs, the O.K./pass load needs to be determined manually by reading the recording chart for the coefficient of friction (and stroke).
9.3.9 Turn off the heater control, release the load to minimum setting, (typically -13 N or -14 N), and remove the test ball and disk test specimen.
