ASTM D2782 Test Method for Measurement of Extreme-Pressure Properties of Lubricating Fluids (Timken Method)
1. Scope
1.1 This test method covers the determination of the load-carrying capacity of lubricating fluids by means of the Timken Extreme Pressure Tester.
NOTE 1 - This test method is suitable for testing fluids having a viscosity of less than about 5000 cSt (5000 mm2/s) at 40°C. For testing fluids having a higher viscosity, refer to Note 7 in 9.1.
1.2 The values stated in SI units are to be regarded as standard. Because the equipment used in this test method is available only in inch-pound units, SI units are omitted when referring to the equipment and the test specimens.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Note 2, Note 3, Note 4, and Note 8.
2. Referenced Documents
2.1 ASTM Standards:
D235 Specification for Mineral Spirits (Petroleum Spirits) (Hydrocarbon Drycleaning Solvents)
D329 Specification for Acetone
D2509 Test Method for Measurement of Extreme Pressure Properties of Lubricating Grease (Timken Method)
D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
G 40 Terminology Relating to Wear and Erosion
2.2 ASTM Adjuncts: ASTM
Three Glossy Prints of Test Blocks Showing Scars (D2782)
3. Terminology
3.1 Definitions:
3.1.1 extreme pressure (EP) additive, n, in a lubricant - a substance that minimizes damage to metal surfaces in contact under high-stress rubbing conditions.
3.1.2 lubricant, n - any substance interposed between two surfaces for the purpose of reducing friction or wear between them.
3.1.3 scoring, n, in tribology - a severe form of wear characterized by the formation of extensive grooves and scratches in the direction of sliding.
3.1.4 wear, n - damage to a solid surface generally involving progressive loss of material, due to relative motion between that surface and a contacting substance or substances.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 load-carrying capacity of a lubricant - as determined by this test method, the maximum load or pressure that can be sustained by the lubricant (when used in the given system under specific conditions) without failure of the sliding contact surfaces as evidenced by scoring or seizure or asperity welding.
3.2.2 OK value, n - as determined by this test method, the maximum mass (weight) added to the load lever weight pan, at which no scoring or seizure occurs.
3.2.3 score value, n - as determined by this test method, the minimum mass (weight) added to the load lever weight pan, at which scoring or seizure occurs.
3.2.3.1 Discussion - When the lubricant film is substantially maintained, a smooth scar is obtained on the test block, but when there is a breakdown of the lubricant film, scoring or surface failure of the test block takes place, as shown in Fig. 1. In its simplest and most recognized form, scoring is characterized by the furrowed appearance of a wide scar on the test block and by excessive pick-up of metal on the surface of the test cup. The form of surface failure more usually encountered, however, consists of a comparatively smooth scar, which shows local damage that usually extends beyond the width of the scar. Scratches or striations that occur in an otherwise smooth scar and that do not extend beyond the width of the scar are not considered as evidence of scoring.
3.2.4 seizure or asperity welding - localized fusion of metal between the rubbing surfaces of the test pieces. Seizure is usually indicated by streaks appearing on the surface of the test cup, an increase in friction and wear, or unusual noise and vibration. Throughout this test method the term seizure is understood to mean seizure or asperity welding.
