ASTM D5182 Evaluating the Scuffing Load Capacity of Oils (FZG Visual Method)
4. Summary of Test Method
4.1 An FZG Gear Test Machine is operated at constant speed (1450 rpm) for a fixed period (21700 revolutions - approximately 15 min) at successively increasing loads until the failure criteria is reached; the initial oil temperature is 90°C beginning at load stage four (see Table 1). The test gears are examined initially and after the prescribed duration at each load stage for cumulative damage (scuffing) to the gear tooth flanks.
5. Significance and Use
5.1 The transmission of power in many automotive and industrial applications is accomplished through the use of geared systems. At higher operating speeds it is well known that the lubricant/additive system can be a significant factor in preventing scuffing (adhesive wear) damage to gears. This test method is used to screen the scuffing load capacity of oils used to lubricate spur and helical (parallel axis) gear units.
5.2 The test method is limited by the capabilities of the equipment (test rig and gears), and the performance observed may not directly relate to scuffing performance observed with spiral bevel on hypoid gearing. It is also limited to discriminating between oils with mild EP additives or less. Lubricants containing higher levels of additives, that is, those meeting the requirements of API GL4 or GL5, generally exceed the maximum load capacity of the test rig and, therefore, cannot be distinguished for their scuffing capabilities by this test method.
