ASTM D3704 Test Method for Wear Preventive Properties of Lubricating Greases
ASTM D3704 Standard Test Method for Wear Preventive Properties of Lubricating Greases Using the (Falex) Block on Ring Test Machine in Oscillating Motion
10. Precision and Bias
10.1 Precision - The precision of this test method is not known to have been obtained in accordance with currently accepted guidelines (that is, in accordance with Committee D-2 Research Report RR: D02-1007, "Manual on Determining Precision Data for ASTM Methods on Petroleum Products and Lubricants").
10.1.1 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 values only in one case in twenty.
23 % of the mean
10.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, exceed the following values only in one case in twenty.
39 % of the mean
NOTE 2 - The precision data were obtained from tests by nine laboratories using five different greases. Four greases used lithium hydroxystearate as a thickener; one used a calcium complex soap system. One grease contained no extreme pressure additive. The other four greases contained leaded, sulfur-phosphorus, MoS2, or calcium complex, respectively, as extreme pressure systems.
10.2 The test conditions used to develop the precision data were:
10.2.1 Time: 5000 cycles (57.14 min),
10.2.2 Angle of Oscillation: 90°,
10.2.3 Test Ring: Type S-10,
10.2.4 Test Block: Type H-30,
10.2.5 Test Speed: 87 1/2 cycles per minute, and
10.2.6 Test Loads on Specimen: 360 lb (163 kg), 480 lb (218 kg), 630 lb (286 kg).
NOTE 3 - Supporting information and data for this method was presented in a research report by G. M. Stanton to the National Lubricating Grease Institute, October 1977 and published in the August 1978 NLGI Spokesman. Copies of this report "Wear Testing of Greases with the Falex I Ring and Block Friction and Wear Test Machine" are available upon request from NLGI.
10.3 Bias - The procedure in this test method has no bias because the value of wear can be defined only in terms of a test method.
