Hybrid ceramic bearings provide a solution to the existing and future technical challenges. The hybrid ceramic bearing adopts steel inner and outer rings and ceramic rollers, which can reduce weight, reduce friction, eliminate electric corrosion, and improve reliability and speed performance.

Nowadays, the world is changing rapidly, and the global trend is changing our travel, business and lifestyle. With the advancement of urbanization, more people are moving to cities. Digitalization and automation are speeding up our life and work pace. The whole society must face the challenges of various environmental problems. At the same time, we also see the rapid development of electrification (especially electric vehicles) and the continuous development of globalization.

These global trends, in turn, are driving changes in the field of bearings. Many emerging technologies require bearings to have special properties, such as being suitable for variable frequency drive, reducing maintenance requirements, helping to improve power density, reducing friction, etc.

Hybrid ceramic bearings provide a potential solution to all these existing and future technical challenges. The combination of steel inner and outer rings and ceramic rollers endows hybrid ceramic bearings with unique properties, making them suitable for various modern applications. SKF hybrid ceramic bearings use silicon nitride rollers. There are two types of deep groove ball bearings and cylindrical roller bearings to choose from, and they can be customized according to customer needs.

The use of ceramic materials in bearings is not new. From the 1960s to the 1980s, ceramic materials were favored by the international aerospace industry because of their light weight and good heat resistance. The industry took the lead in adopting ceramic bearings. However, it was not until the 1980s that the commercial production of ceramic materials (silicon nitride) was realized. Since the 1990s, modern hybrid ceramic bearings have been used in many applications, including machine tools, wind turbines, railway and electric vehicle traction motors, aerospace industry, and fluid machinery such as compressors, pumps and vacuum pumps.

The silicon nitride rolling element used in SKF hybrid ceramic bearing has better characteristics than the standard steel rolling element. The compressive strength of silicon nitride is much higher than that of bearing steel, and its elastic modulus is about one-third higher than that of bearing steel, which helps to reduce friction in rolling contact.

It is important that the hardness of silicon nitride is more than twice that of bearing steel, making it an ideal choice under bad lubrication and other harsh conditions. Compared with bearing steel, silicon nitride is non-conductive and its density is much lower. In addition, the coefficient of thermal expansion of silicon nitride is very low, and the bearing clearance can be accurately adjusted, but the influence of some special working conditions such as ultra-low temperature application needs to be considered.

Silicon nitride can improve the performance of rolling bearings, giving them excellent electrical insulation, weight reduction, excellent friction and wear resistance. In addition, it can significantly improve the speed performance of the bearing.

How do these features solve the challenges posed by specific applications? Why is hybrid ceramic bearing expected to become the standard technology in many industries in the next few years?

Prevent electric corrosion in variable frequency drive device

All the advantages of hybrid ceramic bearings are fully embodied in the variable frequency drive device, which is used to optimize the control of rotating equipment such as pumps and traction motors. Due to the use of pulse width modulation technology, harmful high-frequency current will be generated. When the current passes through the bearing, it may cause damage to the inner and outer rings and rolling elements of the bearing, and affect the performance of the lubricant. The increase of bearing vibration is only the least harmful consequence. What's more, electric corrosion may greatly shorten the service life of bearings and lubricants.

This problem can be easily solved by using hybrid ceramic bearings. Silicon nitride is an electrical insulator, which can prevent the current from passing between the inner and outer rings of the bearing, and even insulate extremely high frequency current, so as to completely avoid bearing failure.

Extended maintenance intervals by extending grease life

The second advantage of hybrid ceramic bearings is their extended maintenance intervals and service life. The ceramic roller can greatly extend the service life of the lubricant, which means that the bearing can operate for a longer time without maintenance. Ceramic rolling element can improve the lubrication state of lubricant on rolling contact surface. Because it reduces friction and electric corrosion, it can avoid thermal degradation of lubricant, so that its lubricating performance can be maintained for a longer time.

In the SKF test, the lubricant life of the mixed ceramic deep groove ball bearing is more than twice that of the full steel bearing of the same specification, and the maximum is nearly seven times. In similar tests on cylindrical roller bearings, the lubricant life in hybrid ceramic cylindrical roller bearings is two to four times that of all steel bearings of the same specification.

High speed performance helps improve power density

The third advantage of hybrid ceramic bearing is that it can achieve higher speed, thus improving power density. This is the general trend of the motor manufacturing industry, especially for the motors used in vehicles such as trains, automobiles and engineering vehicles. Simply put, power is a function of torque and speed. If the speed of the bearing increases, the motor power will also increase.

Why increase power density?

Under the same size, the motor can output higher power

Under the same output power, the motor size can be reduced

P = M•n

The maximum speed is also limited by the bearing size

Because the weight of hybrid ceramic bearing is lighter than that of steel bearing, its speed performance can be improved by 25% at most. In addition, hybrid ceramic bearings have less friction, which means lower operating temperature and longer service life at high speeds. More importantly, increased bearing stiffness helps improve equipment accuracy and reduces the risk of rotordynamic problems.

Reduce friction

Another advantage of hybrid ceramic bearings is the reduction of friction. Reducing bearing friction helps to reduce energy consumption, which is an important consideration in modern industry. The ceramic roller in hybrid ceramic bearing has a direct influence on the friction between rolling and sliding torque. For hybrid ceramic bearings, the higher Young's modulus makes the contact elliptical surface smaller, thus reducing the energy loss caused by rolling torque. In addition, the sliding friction torque is reduced due to the better surface quality of the ceramic roller.

The test conducted by SKF shows that the friction torque of hybrid ceramic bearing at high speed is 5% to 8% lower than that of all steel bearing. At the same time, the test also shows that the hybrid ceramic bearing can well cope with the working conditions of insufficient lubrication and viscosity reduction, which is helpful to reduce friction. The adjustment of these lubrication factors improves the application conditions, and the maximum friction can be reduced by 50% without affecting the service life of the bearing.

Hybrid ceramic bearing -- from solving problems to leading the industry standard

Industry and automobile manufacturing are seeking ways to increase output to meet the challenges of global sustainable development and keep pace with social and technological trends. Hybrid ceramic bearings with ceramic rollers and steel inner and outer rings are expected to solve many problems in design and maintenance, thus improving reliability. In addition to solving technical problems, hybrid ceramic bearings can also achieve more economical operation and higher power output. Therefore, hybrid ceramic bearing is likely to become the standard bearing solution for many applications and industries in the next few years.

Innovative cage design for higher revs

Compared with all steel bearings, the main advantage of hybrid ceramic bearings is that they can achieve higher speed. For manufacturers who want to further improve the speed, advanced bearing cage technology will be of great use. SKF introduced an innovative cage design for hybrid ceramic bearings. This new double piece cage is made of light polymer material polyether ether ketone (PEEK), which can adapt to high-speed operation and reduce heat generation and lubricant performance degradation at high-speed. The rotation speed it can withstand is 60% higher than that of brass cage and 100% higher than that of traditional nylon cage.

More about FRC Ceramic Bearings:

As an important mechanical basic part, ceramic bearings are leading in the world of new materials due to their excellent performance that metal bearings cannot match, such as high temperature resistance and super strength.

Advantages of Ceramic Bearings:

First, because ceramics are almost not afraid of corrosion, ceramic rolling bearings are suitable for operation in harsh conditions full of corrosive media.

Second, because the density of the ceramic rolling ball is lower than that of steel and the weight is much lighter, the centrifugal effect of the outer ring during rotation can be reduced by 40%, thereby greatly extending the service life.

Third, ceramics are less affected by thermal expansion and contraction than steel, so when the bearing clearance is constant, the bearing can be allowed to work in an environment where the temperature difference changes more drastically.

Fourth, because the elastic modulus of ceramics is higher than that of steel, it is not easy to deform when subjected to force, so it is beneficial to improve the working speed and achieve higher precision.

Ceramic bearings have the characteristics of high temperature resistance, cold resistance, wear resistance, corrosion resistance, anti-magnetic and electrical insulation, oil-free self-lubrication, and high speed. It can be used in extremely harsh environments and special working conditions, and can be widely used in aviation, aerospace, navigation, petroleum, chemical, automotive, electronic equipment, metallurgy, electric power, textiles, pumps, medical equipment, scientific research and defense and military fields. High-tech products for new material applications.

The rings and rolling elements of ceramic bearings are made of all-ceramic materials, including zirconium oxide (ZrO2), silicon nitride (Si3N4), and silicon carbide (Sic). The retainer is made of polytetrafluoroethylene, nylon 66, polyetherimide, zirconia, silicon nitride, stainless steel or special aviation aluminum, thereby expanding the application surface of ceramic bearings.

Welcome new and old customers to contact us and know more about our high precision miniature bearings!