ASTM D2266 for wear preventive characteristics of lubricating grease
ASTM D2266 standard test method for wear preventive characteristics of lubricating grease (Four-Ball method)
11. Precision and Bias
11.1 The precision of this test is not known to have been obtained in accordance with currently accepted guidelines (for example, Practice D6300).
11.2 The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
11.2.1 The difference between two test 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 only in one case in twenty:
0.20 mm.
11.2.2 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, in the normal and correct operation of the test method, exceed the following value only in one case in twenty:
0.37 mm.
11.3 Bias - The procedure in this test method for measuring wear preventing characteristics of lubricating grease has no bias because the value of wear preventing characteristics can only be defined in terms of a test method.
NOTE 10 - The following equipment, as listed in the submitted research report, was used to develop the precision statement and no statistically significant differences were found between these pieces of equipment: 1. Falex Corporation (formerly Roxanna Machine Works), 1020 Airpark Drive, Sugar Grove, IL 60555; 2. Precision Scientific (no longer manufactured). To date, no other equipment has demonstrated through ASTM interlaboratory testing the ability to meet the precision of this test. This is not an endorsement or certification by ASTM International.
12. Keywords
12.1 four-ball; grease; wear
