Ceramics (Silicon Nitride) is a common commodity that should have used atleast once in a lifetime. The Pickle Jar or the soup cup what we use at home are good examples for its usage. It does have some characteristic basic advantages very well known to us.
- They are brittle in nature – the tendency to break when suddenly dropped.
- They have good resistance to temperature and are not deformed due to sudden changes of temperature.
- It is easy to obtain a good surface finish on the ceramic component.
Based on the above reasons and some other properties of Ceramics, they have found their application in bearings. The main area of usage of ceramics in bearings is in the rolling elements. The bearings with ceramic rolling elements are termed as “Ceramic Hybrids”.
Well here are the reasons on why and how ceramics were able to take over the position of steel based rolling elements in bearings.
- The weight of the ceramic balls is lesser than their steel counterparts by atleast 50 – 60%. This contributes for the lesser weight of the bearing in total.
- A very high level of surface finish and dimensional stability is very easily attainable in ceramics.
- They exhibit a lower level of vibration compared to steel rolling elements during operation.
- Lesser heat in generated in ceramic hybrids leading to increased life of the bearing lubricant.
- Shafts mounted on Ceramic Hybrid bearings tend to show higher rigidity and higher natural frequency making them less susceptible to vibration.
- The wear rate in the ceramic hybrids is comparatively very less compared to the bearings with steel rolling elements.
Due to the above characteristics of the ceramics certain clear advantages for the bearing are present. They are as follows.
- The life of the bearing is increased atleast two to five times from that of a steel roller using bearings.
- The running speed of the bearings is increased to upto 50% than that of the steel roller using bearings.
- The bearing tends to become electrically non-conductive.
- The overall performance of the system using a ceramic hybrid is greatly enhanced due to this.
A small tabulation on the comparison of steel over ceramic is shown below for reference.
Here are some of the areas of application of the ceramic bearings.
- Machine Tool Spindle Bearings
- Aircraft Bearings – Both the commercial jets as well as the fighter jets