How do you know if you’re using the right grease? You might be using a high-quality grease. You may have put a lot of effort and money into selecting the best quality grease in the pursuit of lubrication excellence. But don’t confuse the quality of the lubricant with the quality of the specification. Considering this lubricating oil analogy, the best quality turbine oil would most likely not make a good engine oil.
Most users are aware of the importance of selecting the right lubricant for a given application. When it comes to selecting lubricating oils for manufactured equipment, it’s easy to determine which products meet the original equipment manufacturer (OEM) requirements. OEM specifications for a lubricating oil normally include viscosity at operating or ambient temperature, additive requirements, base oil type and even special considerations for different environmental conditions. Grease specifications, on the other hand, often lack the detail necessary to make a proper selection, leaving it up to the lubrication engineer to create the specification.
A common OEM grease specification might be to use an NLGI (National Lubrication Grease Institute) No. 2 lithium grease of good quality. Using this information alone, one could select the right consistency and thickener type. A similar specification for an oil-lubricated application would be to use a “good quality lubricating oil.” What?!
Due to the lack of specificity in most grease recommendations, it is important to learn how to properly select greases for each application in the plant. Proper grease specification requires all of the components of oil selection and more. Other special considerations for grease selection include thickener type and concentration, consistency, dropping point and operating temperature range, worked stability, oxidation stability, wear resistance, etc. Understanding the need and the methods for appropriate grease selection will go a long way toward improving lubrication programs and the reliability of lubricated machinery. Let’s walk through the grease selection process step by step, starting with the most important property.