SPONSORED POST (Virtual Showroom): Grease hardening is recognised as a significant contributor to the inefficient operation of bearings. As the grease hardens it causes increased friction and heat. As the heat rises, the grease hardening process continues and the bearing runs hotter than normal, indicating that there is a lubrication problem. Attempts to alleviate the problem by re-greasing may add to the problem once the hardened grease is caked in the bearing.
Grease hardening can occur rapidly or gradually, depending on the cause, which could include:
- Grease incompatibility: Mixing incompatible greases will lead to oil separation and grease hardening.
- Contamination: Dirt, dust, ash and similar contaminants in the grease cause elevated rates of bearing wear and can also act as thickeners in the grease, leading to higher friction levels and elevated temperatures.
- High temperatures, particularly in excess of the grease’s drop point, will lead to oil loss from separation and evaporation, causing grease hardening. Excessive temperatures may also cause the oil to oxidize and transform into a thick tar-like substance.
- Over-greasing, mechanical stresses from misalignment and overloading, and under-greasing cause elevated temperatures in the bearing. Excess temperature may cause the drop point to be reached, separation of the oil from the grease and lubricant failure. Over-greasing will lead to churning which causes more heat, and likely lubricant failure, leading to grease hardening.
- Loss of oil as a result of mechanical forces imposed by the bearing rolling elements on the grease. The oil is squeezed from the grease base and in some circumstances the grease base may not fully recover and totally re-absorb the oil. This can lead to gradual grease hardening. Spherical roller bearings are more prone to creating this problem than other bearing types.
- Constant pressure applied to grease can cause it to separate and some greases are more prone to separation under these conditions than others.
- Continuous vibration and centrifugal force are causes of oil separation and grease hardening. The correct lubricant must be selected to ensure that the effect is minimised.
GreaseMax lubricators are designed to provide efficient, cost-effective, continuous lubrication, preventing grease hardening and the problems that it creates.
For more information, visit Creamer Media’s Virtual Showroom