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Basic Concepts on Miscibility of Fats

The mixture of lubricants, regardless of their consistency and composition, is It is not advisable from the point of view of good lubrication practice that the properties of the mixture of several lubricants can be altered and the actual behavior of this mixture may be different from the theoretical behavior.

However, in many cases it is very difficult to avoid mixing lubricants and in particular the blending of fats for technical reasons or economic. It is therefore necessary to refer to a miscibility table theoretical.

To do this, we take into account the miscibility of its majority components, that is, base oils and thickeners, summarized in the following tables:

Result of a static test of miscibility of fats

To determine if two lubricating greases are completely miscible, it is necessary to carry out laboratory tests in different proportions (10/90, 50/50, 90/10). With miscibility tests, it can not be guaranteed that the mixture will have the same performance as the separated greases, which is why the study must be completed with dynamic mechanical tests with different proportions. However, they allow the prediction of effects, such as the inhomogeneous mixture of greases, a clear separation in two phases, a loss of consistency, an extreme variation of the point of drop or a separation of the oil, and to provide the measures the most suitable for programming a correct transition between lubricants.

Considerations about miscibility between fats and oils

The miscibility of a grease with an oil is a phenomenon that is often ignored because it is uncommon. However, in the case of lubrication of bearings type mechanisms, open or closed gears, chains, ... which are impregnated with an anticorrosive product, it is essential to know the miscibility between the two components grease and antirust. If rust removal is not anticipated with a cleaning solution, it is possible to cause degradation of the characteristics of the grease, or a lack of adhesion to the metal surface (case of greases based on PFPE for high temperatures, but also special formulation greases, based on polyglycol or other combinations).

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