As an important mechanical component, bearings can be said to be one of the representatives of material applications in the industrial field. With the development of materials science, bearings are able to transmit more power in a smaller volume and achieve higher and higher power densities. One of the secrets to Timken's success as a global leader in the bearing industry is arguably due to its relentless research into materials science. After nearly 120 years, Timken has a better grasp of the impact of materials on bearings and drivetrains. From this point it seems easier to understand why TIMKEN bearings are so good and performant.
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The relationship between bearing material and performance
The position of the bearing application is the key to the operation of the equipment, which puts forward extremely high requirements for the performance of the bearing. Selecting the right material for the application is key to ensuring bearing performance. For example, high temperature applications, ultra-low temperature applications, high impact load applications, multi-impurity environment applications, high speed applications, corrosive atmospheres and other harsh use environments, we must use appropriate materials and heat treatment processes according to different application requirements.
Bearing steel
With the development of science and technology, the materials used in bearings are becoming more and more diversified, but the selection and processing of steel is still the most important factor in determining the overall performance of bearings.
1. The purity of the steel
The bearing life we calculate is based on the life of the bearing in which fatigue spalling occurs, and the purity of the bearing steel has a direct effect on fatigue spalling. This is because the steel of the bearing can not be 100% pure, there will inevitably be some non-metallic inclusions, in the bearing bearing rotation process, the inclusions will produce stress concentration around the inclusions, over time, the stress concentration will produce cracks, when the crack develops to the raceway surface, the bearing will produce fatigue peeling.
Demonstration of the source of cracks caused by inclusions to the fatigue spalling process
The diagram above shows the evolution of the source of inclusions to cause cracks and eventually fatigue spalling, showing that purity has a decisive influence on the fatigue life of bearings. The purity of the material is closely related to the chemical composition, melting method, and thermal processing technology of the steel. If there are too many non-metallic inclusions or too large a size, the material is prone to fatigue crack sources, which can propagate and eventually peel off as the bearing is used further.
The relationship between inclusions and the fatigue life of the bearing
With the in-depth research of materials, the life of bearings has been qualitatively improved. At Timken, we follow strict Material Control Standards (GMQ) and Quality Management Systems (TQMS) to ensure the purity and quality of our bearing materials, enabling our bearings to maximize their performance with the most appropriate materials.
2. Heat treatment of materials
At present, the bearing heat treatment process on the market mainly includes low-carbon steel carburizing and high-carbon steel hardening. The ultimate goal of heat treatment is to obtain bearing materials with longer fatigue life, higher geometric stability and surface hardness that meets the requirements of use. The uniformity of the structure and the size of the grain have a crucial impact on the properties of the material.
As an authority on tapered roller bearings, Timken has in-depth research and application of a wide range of heat treatment processes. Through the mature control of the heat treatment process, the heat treatment structure of the material applied in the bearing is more uniform, the grain control is more refined, and the bearing material with better physical properties is obtained. For general application conditions, we use fully hardened steel as the bearing material, but if the impact load is large or the operating environment is more impurities, we choose carburized steel, which can ensure that the bearing has good impact resistance, and at the same time can inhibit the bearing damage caused by impurities. According to different working conditions, the selection of the most suitable bearing material is the key to the realization of bearing technology.
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Bearing materials are diversified
In addition to steel, a wide range of materials can be selected for different bearing components. How to make these unique materials help bearings show good performance is also a problem we should consider. For example, the inner ring and outer ring of the bearing can be selected from various types of metal materials; The rollers can be made of metal or ceramic materials; The cage can be made of metal materials, polymer materials, etc.; Sealing can be made of metal materials, polymer polymer materials, etc. Although the bearing is a standard part, the diversity of its internal composition is rich and colorful.
Material application for common bearing components
Ceramic balls
Brass cage
Steel cages
Everything is changing, and the world of materials is wonderful. May these materials, which contain countless activists, continue to escort the progress of human technology. For more information on bearing materials, contact a Timken engineer.