Writer: Eric Bearing Limited
SKF bearing heat treatment method introduction summary
The quality of heat treatment is directly related to the quality of subsequent processing, which ultimately affects the performance of the parts. The service life of the heat treatment machinery industry is a major energy consumer and the largest polluter. In recent years, scientific and technological progress and the application of heat treatment technology in heat treatment have mainly reflected the following aspects: clean heat treatment production, waste water, exhaust dust noise Electromagnetic radiation environment causes pollution to solve heat treatment environmental pollution .
Surface coating technologies includePhysical vapor deposition (PVD), chemical vapor deposition (CVD), radio frequency sputtering (RF), ion spraying, chemical plating, etc. [38~42]. Compared with CVD, PVD has a low temperature growth of the workpiece to be processed in the process, no heat treatment is required after plating, and it is widely used in the surface treatment of SKF bearing parts. Steel bearing parts such as 100Cr6 and 440C are PVD, CVD or RF plated with TiC, TiN, TiAlN, etc., which can improve the wear resistance and contact fatigue resistance of SKF bearing parts and reduce the surface friction coefficient.
SKF has developed two coating technologies in recent yearsOne is to use PVD to coat diamond ring carbon (DLC) with extremely high hardness on the surface of bearing rings and rolling elements. The surface hardness is 40~80% higher than that of hardened bearing steel. The coefficient of friction is similar to PTFE or MoS2. It has self-lubricating properties. , And the combination with the substrate is good, no flaking, the bearing life and wear resistance are greatly improved, and it can still work normally in the case of oil cut, known as "NoWear bearing";The second is to use PSC to spray a layer of aluminum oxide with a thickness of 100μm on the outer circumferential surface of the outer ring of the bearing, so that the insulation capacity of the bearing is up to more than 1000V, and the bearing has a higher insulation capacity by increasing the thickness of the aluminum oxide. The coated aluminum oxide is firmly combined with the substrate, and can also improve the corrosion resistance of the bearing. The plated bearing can be installed like a normal bearing.
Low temperature ion sulfidation is a surface modification technology that appeared in the late 1980s.The basic principle is similar to ion nitriding. Under a certain degree of vacuum, the high-voltage direct current is used to ionize the sulfur-containing gas. The generated sulfur ions bombard the surface of the workpiece, and react with iron on the surface of the workpiece to form a sulfide with a thickness of about 10 μm mainly composed of FeS. Physical layer. Sulfide is a good solid lubricant, which effectively reduces the friction coefficient of the steel contact surface, and as the load increases, the friction coefficient is further reduced, so the wear resistance of the bearing under heavy load can be greatly improved, and the life of the SKF bearing can be increased About 3 times. SKF NJ 2212 ECP bearings online , pls click here :
The quality of heat treatment is directly related to the quality of subsequent processing, which ultimately affects the performance and life of parts. At the same time, heat treatment is also a major energy consumer and a major polluter in the machinery industry.In recent years, with the advancement of science and technology and its application in heat treatment, the development of heat treatment technology is mainly reflected in the following aspects:
1. Clean heat treatmentWaste water, waste gas, waste salt, dust, noise and electromagnetic radiation formed by heat treatment production will cause pollution to the environment. To solve the environmental pollution problem of heat treatment, the implementation of clean heat treatment (or green environmental heat treatment) is one of the development directions of heat treatment technology in developed countries. In order to reduce the emissions of SO2, CO, CO2, dust and coal slag, the use of coal as fuel has been basically eliminated, and the use of heavy oil has become less and less. The majority of light oil is used. Natural gas is still the most ideal fuel. The waste heat utilization of the burner has reached a very high level. The optimization of the burner structure and the strict control of the air-fuel ratio ensure that NOx and CO are reduced to a minimum under the premise of reasonable combustion; the use of gas carburization and carbonitriding And vacuum heat treatment technology is used to replace salt bath treatment to reduce the pollution of waste water and CN-toxic substances to water sources; water-soluble synthetic quenching oil is used to replace part of the quenching oil, and biodegradable vegetable oil is used to replace part of the mineral oil to reduce oil pollution.
2. Precision heat treatmentPrecision heat treatment has two meanings: on the one hand, it uses physical metallurgical knowledge and advanced computer simulation and testing technology to optimize process parameters according to the use requirements, materials, and structural dimensions of the parts, to achieve the required performance or maximize the use of materials On the other hand, it is sufficient to ensure the stability of the optimized process, to achieve a small (or zero) product quality dispersion and zero heat treatment distortion.
3. Energy-saving heat treatmentScientific production and energy management are the most potential factors for efficient use of energy. Establishing a professional heat treatment plant to ensure full production and give full play to equipment capabilities is the choice of scientific management. In terms of heat treatment energy structure, primary energy is preferred; full use of waste heat and waste heat; low energy consumption and short cycle technology is used to replace long cycle and high energy consumption technology.
4. Less oxidation-free heat treatmentFrom the use of protective atmosphere heating instead of oxidizing atmosphere heating to controlled atmosphere heating with precise control of carbon potential and nitrogen potential, the performance of parts after heat treatment is improved, heat treatment defects such as decarburization and cracks are greatly reduced, and the amount of finishing after heat treatment is reduced , Improve the utilization rate of materials and machining efficiency. Vacuum heating gas quenching, vacuum or low-pressure carburizing, nitriding, nitrocarburizing and boronizing can significantly improve quality, reduce distortion, and increase life.
The heat treatment quality control of bearing parts is the most stringent in the entire machinery industry. SKF bearing heat treatment has made great progress in the past 20 years, mainly manifested in the following aspects: heat treatment basic theory research; heat treatment process and application technology research; new heat treatment equipment and related technology development.