What is the dropping point of a lubricating grease?

Lubricating greases are composed of a base oil, additives and a thickener. The thickener is responsible for forming a structure that will release the oil and the additives that will provide lubrication when the grease is stressed.

There are several different types of thickener, each of which has a different effect on the properties of the lubricating grease. These include the dropping point. This property of the grease is defined as the maximum temperature at which the thickener loses its capacity to retain the oil, resulting in the separation of the two components. The table below shows the typical dropping points of the different thickener technologies. These may vary due to the composition or production process of the individual technologies:

It is crucial to distinguish between the dropping point and the maximum use temperature of the grease. This temperature will always be below the dropping point, and is the maximum temperature to which the grease is recommended to be exposed for optimal performance. Beyond this point, the oil will not separate, but the degradation of the grease will be greatly accelerated.

The dropping point is a measurement commonly found in data sheets and is used as a quality control measure after the production of greases, particularly in soap thickener greases, to ensure that the thickener has been correctly formed.