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
10. Report
10.1 Report the following information:
10.1.1 All parameters used to evaluate materials as follows:
10.1.1.1 Test temperature, °C,
10.1.1.2 Test break-in load, N,
10.1.1.3 Test frequency, Hz,
10.1.1.4 Test stroke, mm,
10.1.1.5 Test ball material,
10.1.1.6 Test disk material, and
10.1.1.7 Test oil sample.
10.2 Report both wear scar measurements taken on the ball (d1, d2) and the average WSD.
10.3 Report all measurements of the coefficient of friction, fmin, fmax, f15, f30, f90, f120, and the magnitude of any strong fluctuations in the coefficients of friction, and when required by specification, include a copy of the friction recording.
10.4 Report the depth of the wear scar on the lower specimen disk if a profilometer reading was made.
11. Precision and Bias
11.1 Data for the precision calculations was obtained by DIN 51834. Twenty-two cooperators tested three lubricating oils, an engine oil, an anti-wear hydraulic oil, and an industrial EP gear oil, in the SRV apparatus. The test load for the engine and hydraulic oils was 300 N and that for the gear oil 200 N. The test temperature was 50°C, the frequency was 50 Hz, and the stroke amplitude was 1 mm for all three test oils. Average coefficients of friction ranged from 0.126 to 0.140 for the engine oil, 0.111 to 0.119 for the hydraulic oil, and 0.112 to 0.127 for the gear oil. Average ball wear scars (WSD) were 0.77 mm with the engine oil, 0.51 with the hydraulic oil, and 0.62 with the gear oil.
11.2 Precision - The precision of this test method, as determined by statistical examination of the interlaboratory test results described in 11.1 is:
11.2.1 Average Ball WSD:
11.2.1.1 Repeatability - The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty.
0.1 mm
11.2.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on the identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty.
0.2 mm
11.2.2 Coefficient of Friction, f:
11.2.2.1 Repeatability - The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty.
0.02
11.2.2.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on the identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty.
0.04
11.3 Bias - The evaluation of friction and wear properties of lubricating oil by this test method has no bias because coefficients of friction and WSD can be defined only in terms of the test method.
12. Keywords
12.1 coefficient of friction; EP additives; lubricating oil; oscillation; SRV; wear
