It is very important to understand the disadvantages of […]
It is very important to understand the disadvantages of ceramic bearings before application. This article will focus on the pros and cons of ceramic bearings.
The atomic structure of ceramic bearings, the covalent bond inherent in non-metals. This means that they share electrons and this atom has a strong adsorption force. For this reason, ceramic bearings provide some better performance than metal bearings. They are usually very hard, flexible, and lightweight. This means that when the shape changes, the load is applied together with the improved wear resistance. The ceramic bearing runs without lubrication. This is because ceramic materials are not micro-welded. Micro welding occurs, usually with metal, when the defects on the rolling element and raceway surface interact with another cause arc. This reduces the surface and greatly reduces the life of the bearing. Ceramic materials do not have such problems, which makes them suitable for various applications that require a free lubricant environment.
They usually behave in a stable manner at high temperatures which means there is less thermal expansion. It requires a lot more energy to increase the bond length of a covalent bond compared to a metal ion bond. Ceramics are non-metallic, non-ferrous materials. When exposed to water and other harmful chemicals they do not corrode in the same way as metals. Their high corrosion resistance allows them to perform well in humid and chemically corrosive environments.
Many engineering ceramics also have low density, resulting in the bearing' working speed, which is improved due to low centripetal force and reduced friction.
Due to the lack of free electrons in most ceramics, they are non-magnetic and excellent insulators.
When studying ceramic bearings, the first thing people may notice is that they are basically more expensive than metal. There are many reasons.
There are extremely high energy and processing costs associated with the large amount of energy required to reach the temperature required for the high-grade raw material sintering process. Because ceramics are so hard, the processing and grinding costs are rapidly increasing when manufacturing precision bearings. All of this must be done in a clean environment with skilled labor. Ceramics are incredibly sensitive to impurities in their pores, so any contaminants may cause premature failure. As the size increases, the price also increases exponentially because of the high cost and processing method requirements. These include the need for a slower sintering process to overcome the temperature gradient in the green body, the amount of uniform pressure applied in a larger volume and the resulting machine cost.
Ceramic bearings have lower load carrying capacity compared to metals and are sensitive to thermal shock. Thermal shock is when temperature gradients within a material cause different expansions, which can cause internal stress. This pressure can exceed the strength of such materials to form cracks.
Ceramics are also more difficult to achieve high-quality surface finish. It can grind them to a surface finish of radium 0.1, which allows to achieve a P5 accuracy level. However, due to recent technological advancements, higher precision classes are now available for Carter ceramic bearings.