Analysis on characteristics and common problems of SKF imported bearings
Analysis on characteristics and common problems of SKF imported bearings
2022年4月25日
Limit speed problem and noise treatment method of SKF Bearing
Limit speed problem and noise treatment method of SKF Bearing
2022年4月25日

Six precautions for selecting NTN imported bearing

  • Size, direction and nature of NTN imported bearing load [the load capacity of the bearing is expressed by the basic rated load, and its value is contained in the bearing size table] the bearing load is rich in changes, such as the size of the load, whether there is only radial load, whether the axial load is unidirectional or bidirectional, the degree of vibration or impact, etc. After considering these factors, we can choose the appropriate bearing type.
  • Generally speaking, the radial load capacity of NTN imported bearings with the same inner diameter increases in the following order: deep groove ball bearing < angular contact ball bearing < cylindrical roller bearing < tapered roller bearing < self-aligning roller bearing
  • The analysis of the relative inclination between the inner ring and the outer ring is the factor that causes the relative inclination between the inner ring and the outer ring of the bearing (such as the deflection of the shaft caused by the load, the poor accuracy of the shaft and housing or installation error), and select the bearing type that can adapt to this service condition. If the relative inclination between the inner ring and the outer ring is too large, the bearing will be damaged due to internal load. Therefore, the type of bearing that can withstand this inclination should be selected.

Generally speaking, the allowable inclination angleincreases imported bearing

  • Cylindrical roller bearing, tapered roller bearing, deep groove ball bearing (angular contact ball bearing), self-aligning roller (ball) bearing 3) NTN imported bearing type whose rigidity can meet the rigidity required by the mechanical shaft system [when the bearing bears load, the contact part between the rolling element and the raceway will produce elastic deformation. “High rigidity” refers to the small amount of deformation of this elastic deformation] in the main shaft of the machine tool and the final reduction device of the automobile, While improving the rigidity of the shaft, we must also improve the rigidity of the bearing.
  • The deformation of roller bearing under load is smaller than that of ball bearing. Applying preload (negative clearance) to the bearing can improve the rigidity. This method is suitable for angular contact ball bearings and tapered roller bearings.
  • The installation space of NTN imported bearing can be accommodated in the bearing installation space.

  • Since the rigidity and strength of the shaft are paid attention to in the design of the shaft system, the shaft diameter, i.e. the inner diameter of the bearing, is generally determined first. However, rolling bearings have a variety of size series and types, and the appropriate bearing type should be selected from them.Six precautions for selecting NTN imported bearing
  • The following bearings are generally used:Six precautions for selecting NTN imported bearing
  • Deep groove ball bearing, contact ball bearing, cylindrical roller bearing
  • Rotation accuracy the type of bearing with the required rotation accuracy [the dimensional accuracy and rotation accuracy of the bearing have been standardized by GB according to the bearing type]? The spindle of machine tool, gas turbine and control machine require high rotation accuracy, high speed and low friction respectively. At this time, bearings with accuracy above grade 5 should be used.
  • The installation and disassembly frequency and methods of regular inspection of installation and disassembly. When the installation and disassembly are frequent, the cylindrical roller bearing with separable inner ring and outer ring, needle roller bearing and tapered roller bearing are more convenient.Six precautions for selecting NTN imported bearing
  • The speed can adapt to the NTN imported bearing type of mechanical speed [the limit value benchmark of bearing speed is expressed by the limit speed, and its value is contained in the bearing size table] the limit speed of bearing is not only taken from the bearing type, but also limited to the bearing size, cage type, accuracy grade, load conditions and lubrication mode. Therefore, these factors must be considered in the selection.Six precautions for selecting NTN imported bearing
  • Ina bearing temperature is too high: when the mechanism is running, the part where the bearing is installed is allowed to have a certain temperature. When touching the mechanism shell by hand, it should be normal not to feel hot. Otherwise, it indicates that the bearing temperature is too high.Six precautions for selecting NTN imported bearing
  • The reasons for the high temperature of INA Bearing are: the quality of lubricating oil does not meet the requirements or deteriorates, and the viscosity of lubricating oil is too high; The mechanism assembly is too tight (insufficient clearance); The bearing assembly is too tight; The bearing race rotates on the shaft or in the shell; Excessive load; Broken bearing cage or rolling element, etc.Six precautions for selecting NTN imported bearing
  • INA Bearing Noise: the rolling bearing is allowed to make slight running noise during operation.

  • If the noise is too loud or there is abnormal noise or impact sound, it indicates that the bearing is faulty. The reason for the noise of rolling bearing: it is more complex. It is the wear of the mating surfaces of the inner and outer rings of the bearing. Due to this kind of wear, the matching relationship between INA Bearing and shell, bearing and shaft is damaged, resulting in the axis deviation from the correct position and abnormal noise when the shaft moves at high speed. When the bearing is tired, the metal on its surface will peel off, which will also increase the radial clearance of the bearing and produce abnormal noise.Six precautions for selecting NTN imported bearing
  •  Insufficient bearing lubrication, dry friction and bearing breakage will produce abnormal sound. After the bearing is worn and shaken, the cage is loose and damaged, which will also produce abnormal noise and damage to the bearing. During the disassembly and inspection of rolling bearing, the fault and damage cause of bearing can be judged according to the damage of bearing.Six precautions for selecting NTN imported bearing
  • Metal spalling on the raceway surface: the rolling element of INA Bearing and the raceway surfaces of inner and outer rings are subjected to periodic pulsating load, resulting in periodic contact stress. When the number of stress cycles reaches a certain value, it will be produced on the working surface of rolling element or inner and outer race raceway
  • Fatigue peeling. If the load of ina bearing is too large, this fatigue will be exacerbated. In addition, improper bearing installation and shaft bending will also produce raceway spalling. The fatigue spalling of bearing raceway will reduce the operation accuracy of shaft and cause vibration and noise of mechanism.
  • INA Bearing burn: the burned bearing has a return fire color on its raceway and rolling element. The causes of burns are generally insufficient lubrication, unqualified or deteriorated lubricating oil quality, and tight assembly of ina bearings.Six precautions for selecting NTN imported bearing
  • Plastic deformation: uneven pits appear on the contact surface between raceway and roller of INA Bearing, indicating plastic deformation of bearing. The reason is that under the action of large static load or impact load, the local stress on the working surface of the bearing exceeds the yield limit of the material, which generally occurs on ina bearings rotating at low speed.Six precautions for selecting NTN imported bearing
  • INA Bearing Race crack: the crack of bearing race may be caused by too tight bearing fit, loose bearing or inner ring, deformation of INA Bearing containing parts, poor surface processing of ina bearing installation, etc.
  • Broken cage: the reason is insufficient lubrication, broken rolling element, seat ring skew, etc.Six precautions for selecting NTN imported bearing
  • The metal of the cage adheres to the rolling element, which may be due to the rolling element being stuck in the cage or insufficient lubrication.Six precautions for selecting NTN imported bearing
  • Serious wear of race raceway: foreign matters may fall into the race, insufficient lubricating oil or inappropriate lubricating oil brand. In order to ensure the performance of rolling bearings and maintain long-term use under good conditions, NTN imported bearings must be inspected and maintained. This inspection and maintenance is very important to prevent faults in advance. Six precautions for selecting NTN imported bearing
  • It is hoped that regular inspection and maintenanSix precautions for selecting NTN imported bearingce can be carried out according to the operation standards suitable for the operating conditions of the machine. Generally, the following methods are adopted: the inspection under the operating state is based on the rolling sound, vibration Check the temperature and the nature of the lubricant, and judge the supplement or replacement time of the lubricant.Six precautions for selecting NTN imported bearing
  • NTN imported bearing inspection:

  • fully observe the bearings removed due to the regular inspection and replacement of the machine, and check the condition of the raceway surface, whether there is damage and whether it can be reused. Due to the clearance of NSK imported bearing, the inner and outer rings will move relatively under the action of load, which will reduce the stiffness of NSK imported bearing, cause the radial and axial vibration of the shaft, and affect the working accuracy and service life of the machine.
  •  In order to reduce this vibration, for high-precision and high-speed mechanical equipment, the preloading method is often adopted when installing NSK imported bearing, that is, a certain load (radial or axial) is given to NSK imported bearing in advance during installation to eliminate its original clearance, and make NSK imported bearing body and inner and outer rings produce elastic deformation, so as to prevent relative movement between inner and outer rings during operation. Six precautions for selecting NTN imported bearing
  • The temperature of IKO imported bearing can generally be inferred from the temperature outside the bearing chamber. It is more appropriate if the oil hole can be used to directly measure the temperature of the outer ring of the bearing.Six precautions for selecting NTN imported bearing
  • Generally, the temperature of IKO inlet bearing starts to rise slowly with the operation of the bearing, and reaches a stable state after 1-2 hours. The normal temperature of IKO imported bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are appropriate, the bearing temperature will rise sharply and abnormal high temperature will occur. At this time, the operation must be stopped and necessary preventive measures must be taken.
  •  Six precautions for selecting NTN imported bearing
Six precautions for selecting NTN imported bearing

It contains impurities, excessive load imported bearing

  • The working temperature of IKO imported bearing can be monitored at any time by using the thermal sensor, and the automatic alarm or stop when the temperature exceeds the specified value can be realized to prevent the occurrence of combustion shaft accident.
  • High temperature often indicates that IKO imported bearing is in abnormal condition. High temperature is also harmful to the lubricant of IKO imported bearings. Sometimes bearing overheating can be attributed to the lubricant of the bearing. If the temperature of the bearing exceeds 125 ℃ for a long time, the service life of the bearing will be reduced. The causes of high temperature bearings include insufficient or excessive lubrication and lubricant. It contains impurities, excessive load, bearing ring damage, insufficient clearance, high friction caused by oil seal, etc.
  •  Six precautions for selecting NTN imported bearing
  • Therefore, it is necessary to continuously monitor the bearing temperature, whether it is the bearing itself or other important parts. If the operating conditions remain unchanged, any temperature change can indicate that a fault has occurred.
  •  Six precautions for selecting NTN imported bearing

  • The periodic measurement of IKO imported bearing temperature can be aided by thermometer, such as IKO imported bearing digital thermometer, which can accurately measure the bearing temperature and display it in ℃ or Fahrenheit.
  •  Six precautions for selecting NTN imported bearing
  • The important IKO imported bearing means that when it is damaged, it will cause the shutdown of the equipment. Therefore, this kind of bearing should be equipped with temperature detector.
  • Under normal circumstances, IKO imported bearings will have a natural temperature rise after just lubrication or re lubrication and last for one or two days. The quality of the products can be directly affected by the quality of the antirust materials after the trial processing, and then the quality of the products can be tested according to the quality requirements of the antirust process. 
  •  Six precautions for selecting NTN imported bearing
  • The antirust auxiliary materials selected for use shall be strictly tested according to the quality standards of different materials after entering the factory. Only after they are qualified can they be issued and used by the supply department. During use, the antirust materials and the prepared solution shall be tested regularly to ensure that the concentration and proportion of the solution meet the process requirements and meet the service performance. The establishment of a complete material acceptance system and quality acceptance standards provides a reliable guarantee for doing a good job in rust prevention management.
  •  Six precautions for selecting NTN imported bearing

  • Cooling water mainly plays multiple roles in Koyo bearing processing, such as cooling, lubrication, cleaning and rust prevention. Its correct use and maintenance directly affect the surface quality of machined parts and the service life of cutting tools. The cooling water used by Koyo bearings can be roughly divided into soda water, emulsion and synthetic grinding fluid. 
  •  Six precautions for selecting NTN imported bearing
  • Basically, more than 50 tons of groove fluid is used for large-scale circulation. The washed grinding products, grinding wheel dust, iron filings and oil stain are easy to cause the corruption and deterioration of the cooling water, resulting in the burn and corrosion of processing parts. Strengthening the scientific management of cooling water can improve its performance, ensure product quality and reduce the use cost of cooling water.
  •  Six precautions for selecting NTN imported bearing
  • In order to ensure that the antirust process can be seriously implemented, the technology department formulates specific assessment rules according to the process requirements, and converts the component value to assess the manufacturer. The first-class antirust management personnel shall conduct a monthly process discipline inspection on the production plant, conduct a comprehensive inspection on the management of cooling water, 
  • Antirust fluid, cleaning fluid and antirust oil, the corrosion rate, cleanliness and oil coating packaging of finished Koyo bearings, the management level of antirust personnel and the detection of monitoring items, score the assessment, and send the assessment results to the production plant. Establish a rust prevention management network from top to bottom, so that the rust prevention work has a good management foundation.
  • Apply antirust oil like finished products. This method must be cleaned before the next process, which is more troublesome.
  •  Six precautions for selecting NTN imported bearing
  •  Six precautions for selecting NTN imported bearing

  • After cleaning, immerse the product in a solution containing 15% – 20% sodium nitrite and 0.6% sodium carbonate, and then stack it. Using this method, the anti rust period is short, which can only be maintained for 7-14 days. Moreover, in the rainy season, due to the humid weather, it can only be maintained for 2-3 days, so it must be reprocessed, which requires labor and money.
  • When the Koyo bearing ring is immersed in the aqueous solution of 5% sodium nitrite and 0.6% sodium carbonate, the antirust effect is good, but many antirust tanks and other equipment are required, which takes up a lot of space and is inconvenient for management