Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1412702
www.machinerylubrication.com | September - October 2021 | 25 to be incompatible, even if the greases are from the same supplier. By definition, two lubricating greases are incompatible when a mixture of the products has physical or performance properties that are inferior to those of the individual greases. When two greases are incompatible, some mixtures will soften, leading to leakage through seals and away from lubricated surfaces. Some mixtures will cause the thickener to release the oil, and the separated oil may run from the bearing housing. Less often, mixtures may harden and cause lubricant starvation and poor grease mobility. Grease incompatibility can lead to lubrication and equipment failure and is, therefore, an important issue. Operators and end-users may not always be aware of the risks involved when considering a change of grease in an application. is is true regardless of whether the grease(s) involved are HPM greases or any other greases. erefore, it is incumbent upon the grease user to ensure compatibility if changing greases. Generally, grease suppliers can provide compatibility infor- mation if asked. e use of publicly available grease compatibility charts is not recommended, as these generalize compatibility based solely on thickener types, whereas incompatibility can be the result of incompatible base oils or additives. It is always the safest choice to have the specific greases evaluated via laboratory testing. If NLGI were to include some sort of compatibility requirement in the HPM speci- fications, it would likely lead to the exclusion of some types of grease thickener technologies, which goes against the HPM specification design principles. And since grease compat- ibility predictions should not be based on generic thickener-based compatibility charts, specific grease pairs should be tested. Given the wide variety of chemistries utilized in grease products, there is no way to include such a compatibility requirement in the HPM specifications. Machinery Lubrication: Where can I find HPM certified greases? NLGI: With the launch of the program to grease manufacturers in late 2020, NLGI is now receiving applications for certification. Grease from the manufacturer is submitted to a third party, the Center for Quality Assurance (CQA), for lab testing to verify that the grease meets the strict performance levels set in the HPM specification. Greases certified by the program will bear the HPM trade- mark showing approval to the core and any sub-category endorsements, as shown in Figure 2. Marketers and manufacturers who market their HPM certified greases must display the HPM trademark on their containers and will be listed on the NLGI website at High-Performance Multiuse (HPM) Grease Certification (nlgi.org). ML ML ML