The Advantages of Ceramic Bearings and Their Big Disadvantage

There are more and more electric vehicles on the road. This increases the demand for ceramic bearings. These bearings are light, electrically insulating and highly resistant to wear and abrasion. This makes them suitable for environments where normal steel bearings fall short. So why not make all your bearings ceramic bearings? We will answer that question in this blog (reading time: 2 minutes).

What is ceramic?

Ceramic materials are found in all kinds of art objects and utensils. We all know tiles, pans, brake discs and dental fillings. The word ceramic is derived from the Greek word kéramos, which translates as “clay” or “baked pot”. This shows the origins of ceramics; a manufacturing process that involves heating.

Ceramic has a number of properties that make it very suitable for use in bearings. Most ceramics are hard, wear-resistant and non-conductive. As early as the 1960s and 1970s, the first ceramic bearings were designed in the US. Today, they are used in sectors like aerospace, medical and automotive industries. New developments in electric vehicles mean they are becoming increasingly popular.

Ceramic materials are found in all kinds of art objects and utensils

Hybrid or all-ceramic

Ceramic bearings are lighter and more durable than ordinary steel bearings. There are several types. Hybrid bearings, such as the Schaeffler HC versions, contain ceramic and steel components. The roller elements are ceramic balls or rollers, while the inner and outer rings are steel. There are also all-ceramic bearings without any steel parts. Often these are made of silicon nitride (Si3N4) or zirconium oxide (ZrO2). Hybrid and full-ceramic bearings offer some advantages. They are:

• Electrically insulating

• Suitable for high speeds

• Highly resistant to wear and abrasion

Hybrid bearings with ceramic roller bodies and steel rings

Electrically insulating and non-magnetic

Ceramic materials are non-conductive. An indispensable quality of bearings in generators, traction motors and other electric motors. Current flow may lead to serious damage in normal bearings, as we pointed out in our blog on premature bearing failure. This will not happen to hybrid bearings. The electrically insulating ceramic balls protect the steel rings from current penetration. Also, full ceramic bearings are non-magnetic. Therefore, they are commonly used in medical devices.

Ceramic roller bodies prevent current penetration

High corrosion resistance and temperature resistance

In addition, ceramic bearings and hybrid versions with stainless steel rings, such as the Schaeffler XC models, are more resistant to corrosion than steel bearings. For example, they can withstand water, detergents, and certain chemicals. They can also take high temperatures. Compared to steel bearings of the same dimensions, higher rotational speeds are possible. Hybrid bearings can handle higher speeds than all-ceramic bearings. In fact, their steel rings are less brittle than ceramic versions. This makes them less susceptible to sudden failure under excessive load or speed.

“Ceramic bearings are more resistant to corrosion and high temperatures.”

Longer life, less maintenance

Ceramic balls have lower density and much higher hardness than steel balls. They are very wear-resistant: small particles that enter the bearing are simply pulverized. And their very low rolling resistance, makes sure that little heat is released. Lubricants last longer that way. Hybrid bearings are also more resistant to adverse lubrication conditions than steel bearings. Fully ceramic ones can be used even without lubricants.

“They are very wear resistant and lubricants last longer.”

Always ceramic from now on?

Super-wear-resistant, able to withstand extreme conditions…. Always ceramic bearings from now on? It depends on their use. Ceramic and hybrid bearings have lower load carrying capacity than their steel counterparts. Because ceramic roller bodies are harder, they deform less. The result is a smaller contact ellipse. Also, the thermal shock resistance of steel models is better. But above all, ceramic versions come with a hefty price tag. This is because the machining of raw materials for these bearings is complex and energy consuming. As a result, production takes a long time. So, please determine which features are important for your application before making your choice!