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
6. Apparatus
6.1 SRV Test Machine (see Fig. 1), consists of an oscillation drive, a test chamber (see Fig. 2), and a loading device with a servomotor and a load cell. The machine is operated by a control device for the oscillating drive, a timer, a load control, a frequency control, a stroke control, a data amplifier to determine the friction coefficient, and a switch and a controller for the heating. An oscilloscope may be used for monitoring. Friction coefficients are recorded in relation to time by a chart recorder, or by data acquisition in a computer.
6.1.1 On the firmly mounted receiving block (1) in the test chamber (see Fig. 3), there is a piezoelectric device (2) to measure the friction force, Ff, and the friction coefficient, f; the holder for the test disk (3) with a thermostat-controlled electrical resistance heating element (4); a resistance thermometer (5); the oscillation drive rods (6); an exchangeable holder for the test ball (7); and the load rods of the loading device (8).
6.1.2 The design of the receiving block for the test disk should be such that it has integrated cooling coils, or that cooling coils are wound round it, so that temperatures below ambient are possible. The test disk (9) and the test ball (10) are inserted into their respective holders (3, 4) (see Fig. 3).
6.1.3 Disks are generally used as the lower test piece. Balls, cylinders, rings, or specialized shapes may be used, with appropriate holders, as the upper test piece (see Fig. 4).
6.2 Microscope, equipped with a filar eyepiece graduated in 0.01-mm divisions or equipped with a micrometre stage readable to 0.01 mm. Magnification should be sufficient to allow for ease of measurement. One to 103 magnification has been found acceptable.
6.3 Syringe, suitable for applying 0.03 mL of the lubricating oil under test.
6.4 Tweezers, straight, round, about 200-mm long, with non-marring tips.
6.5 Torque Wrench, initial torque 0.5 to 5 nm.
6.6 Ultrasonic Cleaner.
7. Reagents and Materials
7.1 Test Balls, AISI 52100 Steel, 60 +/- 2 HRC hardness, 0.025 +/- 0.005-µm C.L.A. surface finish, 10-mm diameter.
7.2 Test Disk, AISI 52100 steel, 62 +/- 1 HRC hardness, 0.45 to 0.65-µm Rz lapped surface, 24 +/- 0.5-mm diameter by 7.8 +/- 0.1-mm thick.
NOTE 2 - Test pieces made to 100 Cr 6 roller bearing steel (see DIN 17230) are equivalent.
7.3 n-Heptane, reagent grade.
NOTE 3 - Warning: Flammable. Health Hazard.
7.4 Isopropanol, reagent grade.
NOTE 4 - Warning: Flammable. Health Hazard.
7.5 Toluene, reagent grade.
NOTE 5 - Warning: Flammable. Health Hazard.
7.6 Cleaning Solvent, a mixture of equal volumes of n-heptane, isopropanol, and toluene.
NOTE 6 - Warning: Flammable. Health Hazard.
