ASTM International approved as a standard a new small scale oxidation test that provides more accurate results for biobased greases. The approval culminates a long effort by the Biobased Greases Working Group - a joint effort between The European Lubricating Grease Institute and the National Lubricating Grease Institute.
The standard is ASTM D8206-18, Standard Test Method for Oxidation Stability of Lubricating Greases - Rapid Small-Scale Oxidation Test. The new procedure is a modification of ASTM D7545 specially adapted for grease testing because previous methods for evaluating properties of mineral oil based greases did not consistently provide satisfactory results for biobased products.
The new method measures the net change in pressure resulting from consumption of oxygen by oxidation and the gain in pressure to due formation of volatile oxidation by-products, according to the web page for ASTM D8206-18. The test method may be used for quality control to indicate batch-to-batch uniformity. It doesnt predict the ability of greases stored in containers for long periods, nor the stability of films of greases on bearings and motor parts, the standards organization noted.
ASTM said that the induction period as determined under the conditions of the test method can be used to indicate oxidation stability. The test method can be used for research and development, quality control and specification purposes. However, the standards organization noted that no correlation has been determined between the results of the test method and service performance.
For more information on ASTM D8206-18, visit the ASTM International website. ASTM is based in the United States in West Conshohocken, Pennsylvania.