Bearings play a very important role in various machinery, and in order to maintain their long-term effective operation, the material of the bearing is generally selected from the bearing steel that is harder and has good wear resistance, but for industrial robots, the commonly used crossed roller bearings need to have higher wear resistance and hardenability.
1. Materials for general bearings
The general bearing material is GCr15, which is high-carbon chromium-bearing steel with low alloy content, good performance, and wide application. After quenching and tempering, it has a high and uniform hardness, good wear resistance, and high contact fatigue performance. The steel has medium cold working plasticity, general cutting performance, poor welding performance, high sensitivity to the formation of white spots, and temper brittleness. Its chemical composition contains: C: 0.95-1.05, Mn: 0.25-0.45, and Si: 0.15-0.35.
GCr15 bearing steel has good overall performance, good cutting performance after spheroidizing annealing, high and uniform hardness after quenching and tempering, high wear resistance and contact fatigue strength, good thermal processing performance, containing fewer alloy elements, and cheaper, but it is not suitable for crossed roller bearings which used for robots.
2. Material for crossed roller bearing
Crossed roller bearings basically use GCr15SiMn bearing steel, which has higher wear resistance and hardenability than GCr15, medium cold working plastic deformation, poor weldability, sensitivity to white spot formation, and temper brittleness during heat treatment. It is very suitable for manufacturing cross-roller bearing rings with wall thickness ≥ 12mm and outer diameter ≥ 250mm and rollers with a diameter ≥ 22mm.
GCr15SiMn bearing steel, as the main material for cross-roller bearings, is a high-carbon, high-chromium-bearing steel. It has higher wear resistance and hardenability than GCr15 steel. The critical quenching diameter in oil is 90~ 110mm (volume fraction of 50% martensite), after 840°C oil quenching, tempered at 350°C, and then light quenched, the surface hardness is as high as 1096HV, and the hardened layer depth can reach 1mm. In view of the insufficiency of the heat treatment process of the forming roller, the thin side is pre-cooled and cooled to produce non-martensitic transformation, resulting in troostite or sorbite, enhancing toughness, reducing stress, and then quenching as a whole to meet the process requirements. Ice-cooling treatment can improve the dimensional stability of crossed roller bearings, or martensite graded quenching to stabilize retained austenite and obtain high dimensional stability and high toughness. GCr15SiMn bearing steel is generally not recommended for forging, it is generally used after quenching and low-temperature tempering.
3. Other materials for bearings
In addition to GCr15 bearing steel and GCr15SiMn bearing steel for crossed roller bearings, GCr6 bearing steel and GCr9 bearing steel are often used in the production of bearings. GCr6 bearing steel is more inclined to make measuring tools, while GCr9 bearing steel is mainly used to make steel balls and rollers.
The hardenability, hardness and wear resistance of GCr6 bearing steel are higher than that of carbon tool steel, and the size changes during heat treatment are not large. Widely used as measuring tools, such as templates, pallets, sample sets, gauges, block gauges, ring gauges, threaded plug gauges, and sample columns, etc., and can also be used to make cold work dies such as wire drawing dies and cold heading dies, as well as low-speed tool cutting.
GCr9 bearing steel has higher wear resistance and hardenability than GCr6 bearing steel, good machinability, moderate cold strain plasticity, poor weldability, and is more sensitive to the formation of white spots. Heat treatment has a tendency to temper brittleness. It is mainly used to manufacture steel balls with diameters of 13.5-25.4mm, tapered rollers with diameters of 10.3-18.5mm, cylindrical rollers with diameters of 9.4-17.2mm, and spherical rollers with diameters of 9.2-17.1mm.
The material of crossed roller bearings has higher wear resistance and hardenability than ordinary bearing steel, and through special processing methods, it can more effectively ensure its dimensional stability, so it is widely used by industrial robots. Luoyang Tedin Bearing Co., Ltd. is a professional manufacturer that mainly produces thin section crossed roller bearings for robots and harmonic reducers. We have rich experience in bearing design and production. Our products are widely used in industrial robots, medical instruments and aerospace, and other industries with high precision requirements.
Check more types of Crossed Roller Bearings.
Please check the Product Guide to select suitable bearings for your machinery.
E-mail: sales@tedin-bearing.com