Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/778560
16 | January - February 2017 | www.machinerylubrication.com showed calcium complex to be incompat- ible with polyurea. Although there were significant disagree- ments between the various charts, they all had one thing in common — few provided any link or reference to research that was conducted to develop them. That is to say, the charts being used to make significant engineering and design decisions are contradictory and do not indicate the source of information or research used to compile them. Upon observation, it becomes obvious that several of the charts are derived from the others. The various descriptions used imply that some may have been copied from the others. Many charts include a disclaimer, usually stating that it would be preferable to clean out all old grease and avoid any mixing, or that the charts are believed to be accurate at the time of publication. This underscores the challenge of finding a single authoritative chart to be used with confidence when making decisions regarding grease mixing. Basis for Grease Compatibility It is interesting to note that these grease compatibility charts focus only on the family of thickener involved. However, there are three components to any formulated grease: the base oil, the additives and the thickener. When mixing oils, the key considerations are the viscosity of each product, the base oil type and the thickener. Somehow, though, these critical parameters are overlooked when utilizing grease compatibility charts. This is somewhat understood, since the most common reason for grease mixing problems is related to differences in the grease thick - ener, but that is not the only issue. Base Oil Compatibility Greases are manufactured from both mineral oil and synthetic oil bases. Some synthetic base oils are incompatible with mineral oils and other types of synthetics, just as in the mixing of lubricating oils. Therefore, it is important to consider the type of base oil in the grease when deter- mining compatibility. If the grease thickeners are compatible but the base oils are not, the resulting mixture can be problematic. Viscosity is critical when selecting any lubri- cant. Likewise, when greases are mixed where the base oil viscosities are significantly different, the resulting mixture will not be optimized for the application. Additive Compatibility It is understood that when oils are mixed, any incompatibility in the additive packages will result in poor performance and often additive reactions creating deposits. While reacting additives will not settle to the bottom in grease, as is the concern in oil, the changes can cause problems, impacting TYPE PROLAB TRIBOLOGY. COM AMSOIL LUBRITENE NSK TRANSIT LUBE EASTERN MARINE Aluminum Complex 1 1 1 1 1 1 1 Barium 1 1 Barium Complex 1 1 1 1 1 Calcium 1 1 1 Calcium Stearate 1 1 1 1 Calcium 12-Hydroxy 1 1 1 1 1 Calcium 12-Hydroxystearate 1 Calcium Complex 1 1 1 1 1 1 1 Bentonite Clay 1 1 1 Clay 1 1 1 1 Lithium 1 1 1 Lithium 12-Hydroxy 1 1 1 1 1 Lithium 12-Hydroxystearate 1 Lithium Complex 1 1 1 1 1 1 1 Sodium 1 1 1 Polyurea 1 1 1 1 Polyurea (Conventional) 1 1 1 Polyurea (Modified) 1 Polyurea Shear Stable 1 1 Polyurea (LUB-LM type) 1 Calcium Sulfonate 1 1 1 1 Silica Gel Silica 1 Polyurea (Lubrilife) Lithium Stearate Compilation of 17 grease compatibility charts GREASES