Time : May 9, 2023
Hybrid ceramic bearings provide solutions for addressing current and future technological challenges. The hybrid ceramic bearing adopts steel inner and outer rings and ceramic rolling elements, which can reduce weight, reduce friction, eliminate electrical corrosion, and improve reliability and speed performance.
Nowadays, the world is changing rapidly, and global trends are changing our way of travel, business, and lifestyle. With the advancement of urbanization, more and more people are migrating to cities. Digitalization and automation are accelerating our pace of life and work, and the entire society must address the challenges of various environmental issues. At the same time, we also see the rapid progress of electrification (especially electric vehicles) and the continuous development of globalization.
These global trends are driving changes in the field of bearings. Many emerging technologies require bearings to have special performance, such as being suitable for variable frequency drives, reducing maintenance requirements, helping to improve power density, and reducing friction.
Hybrid ceramic bearings provide promising solutions for addressing all of these existing and future technological challenges. The combination of steel inner and outer rings and ceramic rolling elements endows hybrid ceramic bearings with unique performance, making them suitable for various modern applications. SKF hybrid ceramic bearings use silicon nitride rollers. There are two types of Deep Groove Ball Bearing 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 due to their light weight and good heat resistance, and the industry was the first to adopt ceramic bearings. However, it was not until the 1980s that ceramic materials (silicon nitride) were commercially produced. Since the 1990s, modern hybrid ceramic bearings have been applied in numerous 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 bearings has superior characteristics compared to standard steel rolling elements. 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.
Importantly, the hardness of silicon nitride is more than twice that of bearing steel, making it an ideal choice for harsh working conditions such as poor lubrication. Compared to bearing steel, silicon nitride is non-conductive and has a much lower density. In addition, the coefficient of thermal expansion of silicon nitride is very low, which can accurately adjust the bearing clearance, but it needs to consider the impact of some special working conditions such as ultra-low temperature applications.
Silicon nitride can improve the performance of rolling bearings, endowing them with excellent electrical insulation performance, weight reduction characteristics, excellent friction performance, and wear resistance. In addition, it can significantly improve the rotational speed performance of the bearings.
How do these features address the challenges posed by specific applications? Why is hybrid ceramic bearings expected to become a standard technology in many industries in the coming years?
Preventing electrical corrosion in variable frequency drive devices
The full advantages of hybrid ceramic bearings are fully reflected in variable frequency drive devices, which are used for optimizing control of rotating equipment such as pumps and traction motors. Due to the use of pulse width modulation technology, harmful high-frequency currents can 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 intensification of bearing vibration is only the least harmful consequence, and even worse, electrical corrosion may greatly shorten the service life of bearings and lubricants.
The use of hybrid ceramic bearings solves this problem easily. Silicon nitride is an electrical insulator that can prevent current from passing between the inner and outer rings of bearings, and can even insulate extremely high frequency currents, completely avoiding bearing failure caused by this.
Extending maintenance intervals by extending the lifespan of lubricating grease
The second major advantage of hybrid ceramic bearings lies in extending maintenance intervals and service life. The ceramic rolling element can greatly extend the service life of the lubricant, which means that the bearing can continue to operate for longer periods without maintenance. Ceramic rolling elements can improve the lubrication state of lubricants on rolling contact surfaces. By reducing friction and electrical corrosion phenomena, the lubricant is avoided from thermal degradation, thus maintaining its lubrication performance 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 twice 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 bearings is that they can achieve higher rotational speeds, thereby increasing power density, which is the overall trend in the motor manufacturing industry, especially for motors used in transportation 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 should we increase power density?
Under the same size, the motor can output higher power
When the output power is the same, the motor size can be reduced
P = M•n
The maximum speed is also limited by the size of the bearings
Due to the lighter weight of hybrid ceramic bearings compared to steel bearings, their rotational speed performance can be improved by up to 25%. In addition, the friction of hybrid ceramic bearings is relatively small, which means lower operating temperatures and longer service life at high speeds. More importantly, increasing bearing stiffness helps improve equipment accuracy and reduces the risk of rotor dynamics problems.
Reduce friction
Another advantage of hybrid ceramic bearings is reduced friction. Reducing bearing friction helps to reduce energy consumption, which is an important consideration in modern industry. The ceramic rolling element in hybrid ceramic bearings has a direct impact on the friction generated by rolling and sliding torque. For hybrid ceramic bearings, due to the high Young’s modulus, the contact elliptical surface is smaller, thereby reducing the energy loss caused by rolling torque. In addition, the sliding friction torque is also reduced due to the better surface quality of ceramic rollers.
The experiments conducted by SKF show that the friction torque of hybrid ceramic bearings is 5% to 8% lower than that of all steel bearings at high speeds. At the same time, experiments have also shown that hybrid ceramic bearings can effectively cope with conditions of insufficient lubrication and reduced viscosity, which helps to reduce friction. The adjustment of these lubrication factors improves the application conditions, and can reduce friction by up to 50% without affecting the bearing service life.
Hybrid ceramic bearings – from problem-solving to leading industry standards
The industrial and automotive manufacturing industries are finding ways to increase production to meet global sustainable development challenges and keep up with social and technological trends. A hybrid ceramic bearing using ceramic rolling elements and steel inner and outer rings is expected to solve various design and maintenance problems, thereby improving reliability. In addition to solving technical problems, hybrid ceramic bearings can also achieve more economical operation and higher power output. Therefore, hybrid ceramic bearings are highly likely to become the standard bearing solution for many applications and industries in the coming years.
Innovative cage design helps achieve higher rotational speeds
Compared to all steel bearings, the main advantage of hybrid ceramic bearings is that they can achieve higher rotational speeds. For manufacturers who want to further increase the speed, advanced bearing cage technology will be of great use. SKF has launched an innovative cage design suitable for hybrid ceramic bearings. This new dual piece cage is made of lightweight polymer material polyether ether ketone (PEEK), which can adapt to high-speed operation while reducing heating and lubricant performance degradation at high speeds. It can withstand 60% higher rotational speed than brass cages and 100% higher than traditional nylon cages.
More about XBRG Thrust ball bearings:
Thrust ball bearings are separable bearings. The single-acting thrust ball bearing consists of a shaft washer, a housing washer and a ball set with cage. The double-acting type consists of a shaft washer (centre washer), two housing washers and two ball sets with cages. Thrust ball bearings can be applied for high axial loads and low to medium speeds. However, they cannot take radial loads.
http://xinzhou.bearingshow.net/product-cat/thrust-ball-bearings/
English 
Deutsch 
Español 
Português 
Русский 
Italiano