We have already analyzed the importance not only of the choice of lubricant to be used in a bearing but also of maintenance operations.
Sometimes, however, the correct choice of lubricant or carrying out the appropriate maintenance operations are very difficult or impossible; for example:
The result of situations like these is that the bearings do not operate in optimal conditions, causing them to be replaced prematurely. Frequent maintenance operations lead to machine downtime which may not be economically acceptable.
A solution to all these problems is represented by full ceramic bearings, i.e. bearings made with:
The characteristics of full ceramic bearings which, in relation to the problem of lubrication, make them a very interesting solution, sometimes the only one, are listed below:
The hardness of ceramic materials is, due to the intrinsic characteristics of this type of material, much higher than the hardness that steels for bearings reach after hardening.
Rolling elements and rings made of ceramic material have a lower roughness than that obtainable with bearing steels.
The coefficient of friction of ceramic materials is lower than the coefficient of friction of steels for bearings.
Ceramic materials exhibit extremely high temperature resistance. In fact, Zirconium Oxide can be used up to 500 °C and Silicon Nitride up to 800 ° C while bearing steels, unless special treatments, can be used up to 150 °C.
Zirconium Oxide and Silicon Nitride are chemically inert against many chemicals that are fatal for steel bearings (acids, bases, organic compounds, water, salt spray, etc.).
The characteristics listed above give a very important advantage to full ceramic bearings: wear resistance is better than that of steels.
Let's see why.
Let's consider two bearings, one made of steel and the other one of ceramic material, of the same size and operating under the same load.
Wear is mainly caused by two effects: mechanical abrasion and temperature rise.
Since mechanical abrasion is linked to the roughness of the surfaces in contact, in ceramic materials this phenomenon will have less relevance because the roughness is lower than that obtainable in steel bearings.
The temperature rise in the ceramic bearing will be lower than that of the steel bearing. In fact, since ceramic materials have a higher hardness than steels for bearings, the contact surface between the rolling element and the race in the full ceramic bearing will be smaller than that present in the steel bearing. A smaller sliding surface associated with a lower coefficient of friction results in less heat generated.
Ultimately, the ceramic bearing shows a higher wear resistance than the steel bearing.
All this leads to an extremely important result: full ceramic bearings can operate under lubrication conditions that are impossible for steel bearings.
Some examples of use can be the following:
We explained to you just few of the many aspects that make this product the best ally of your machines. Learn about the benefits and operation of bearings, based on the applications you need to optimize, with our experts.