Regular lubrication and maintenance of KOYO bearings

Proper lubrication and maintenance can maximize the life of KOYO bearings.
1, grease lubrication
The relubrication of KOYO bearings is best carried out during the planned downtime of the equipment and is periodically replenished, while the old grease is removed or the old grease is squeezed out through the drain. Wipe the grease fittings clean before adding fresh grease. If the KOYO bearing housing does not have a grease fitting, the KOYO bearing housing cover or end cap should be opened to remove the old grease and, after cleaning, replenish the same type of fresh grease.
2, lubricating oil lubrication
Regularly check the oil level and oil quality of the lubricating oil. Under normal circumstances, the normal oil level should be within the range of 1/3-2/3 of the equipment oil level window or mark. The oil filling method is oil cup, the oil level shown only represents the oil replenishing capacity, and the oil level of KOYO bearing housing is to meet the operation requirements. The oil level in the oil cup is less than 1/4 of its total volume.
Check and replenish the oil method, take a small amount of lubricating oil as a sample and compare it with fresh oil. The competent unit can consider the oil quality test to ensure the oil quality is qualified. If the sample looks cloudy, it may be the result of mixing with water, which is commonly referred to as oil emulsification. At this point, the lubricant should be replaced. If the sample is darkened or thickened, it may indicate that the lubricant has begun to carbonize and the old lubricant should be completely replaced. If possible, flush the oil line with fresh oil. When changing the lubricating oil, make sure that the new and old models of the replaced oil are the same and supplement the required oil level.
Use an oil bath type lubrication system. If the oil temperature is below 60 ° C (140 ° F) and the lubricant is not contaminated, replace the lubricant once a year. If the oil temperature is between 60-100 ° C (140-210 ° F), the lubricant needs to be replaced four times a year. If the oil temperature is between 100-120 ° C and 210-250 ° F, the lubricant needs to be replaced once a month. If the oil temperature is above 120 ° C (250 ° F), the lubricant needs to be replaced once a week.
Proper installation and maintenance are important factors in the normal operation of KOYO bearings. At the same time, care must be taken to maintain the cleanliness of KOYO bearings. KOYO bearings must be protected from contaminants and moisture and must be properly installed and lubricated. In addition, KOYO bearing design, oil seal condition, lubricant form and replacement cycle and special maintenance also play an important role, and must be paid attention to.

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Reasons for damage to imported bearings

First, improper installation (about 16%)
1. Use brute force during installation. Directly hitting the bearing with a hammer will cause the greatest damage to the imported bearing; it is the main cause of deformation.
2, the installation is not in place, the installation is biased or not installed in the imported bearing position, resulting in too small clearance of the imported bearings. The inner and outer rings are not in the center of uniform rotation, causing disagreement.
Recommendation: Select an appropriate or professional imported bearing installation tool, and use a special instrument to detect it after installation.
 Second, poor lubrication (about 36%)
According to the survey, poor lubrication is one of the main causes of premature failure of imported bearings. The main reasons include: not adding lubricant or lubricating oil in time; lubricant or lubricating oil is not filled in place; improper selection of lubricant or lubricating oil; inaccurate lubrication method, etc.
Recommendation: Choose an accurate lubricant or lubricant and use an accurate lubrication method.
Third, pollution (about 14%)
Pollution can also lead to premature damage to imported bearings. Contamination means that dust, metal chips, etc. enter the inside of the imported bearings. The main reasons include: opening the imported bearing packaging too early before use, causing pollution; the working environment is not clean during installation, causing pollution; the working environment of the imported bearings is not clean, and the working medium is polluted.
Recommendation: It is best not to disassemble the packaging of the imported bearings before use; keep the installation environment clean during installation, clean the imported bearings to be used; and strengthen the sealing device of the imported bearings.
 Fourth, tired (about 34%)
Tired damage is a common form of damage to imported bearings. Common causes of fatigue damage may be: long-term overload operation of imported bearings; failure to repair in time; improper maintenance; equipment aging.
Recommendation: Select the appropriate type of imported bearings and replace the worn bearings in time.
The above are the most common causes of early damage to imported bearings; the reasons for the early damage of imported bearings are various. The above are the main reasons for consideration, and sometimes it may be a comprehensive cause. If the imported bearing is selected accurately, the installation method is accurate, the lubrication method and lubricant selection are accurate, and the imported bearings can work normally for a long time.

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What are the main properties of spindle bearing oil, and what is the role?

Spindle bearing oil is a special lubricant for spindle bearings of precision machine tools and similar equipment. It plays an important role in ensuring the working accuracy and performance of the spindle and prolonging its service life. It is also called bearing oil.
Its main performance:
1. Suitable viscosity and good viscosity temperature characteristics
In order to make the machine tool spindle temperature not too high, the machine tool will be thermally deformed, affecting the machining accuracy or making the bearing poorly lubricated. The lubricating oil of the appropriate temperature should be selected according to the spindle bearing structure, the rotating speed and the bearing clearance, and it is required to have good viscosity-temperature characteristics. To prevent the change in viscosity due to excessive changes in the operating temperature of the spindle and the ambient temperature, which affects the lubrication performance.
2. Good lubricity
In order to maintain a uniform oil film between the main shaft and the bearing contact surface, and the impact film is not damaged when the spindle starts or stops moving, maintaining good lubrication performance reduces friction and friction heat, reduces spindle temperature rise, and ensures The effect of processing accuracy requires good lubrication performance.
3. Good oxidation resistance
When the machine tool spindle adopts the circulating lubrication method, the spindle bearing oil is required to be used for a long time without deterioration, so it is required to have good oxidation resistance.
4. Good rust resistance
Since the oil is inevitably mixed into the condensed water in the air or the machine coolant during the operation of the spindle lubrication system, the oil is required to have good rust resistance.

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How to check the fault of the running bearing and how to deal with it

    Today, we will discuss how to check the rolling sound, vibration, temperature and lubrication status of imported bearings during operation so as to find and solve problems in time to avoid unnecessary economic losses.

    Today is mainly to check the rolling sound, vibration and temperature of the imported bearings. We will explain this in more detail in future articles.

    The first is to identify and check according to the sound of the rolling of the imported bearings. We can use the sounder to check the size and sound quality of the rolling sound of the imported bearings in operation. Because the imported bearings emit abnormal noises and irregular sounds even if they are slightly peeled off, they can be distinguished by the sounder, which can prevent them in advance.

    Secondly, the vibration of the imported bearing in the work to identify and inspect, the vibration of the imported bearing is very sensitive to the damage of the bearing. For example, peeling, indentation, rust, cracks, abrasion, etc. are reflected in the vibration measurement of the imported bearing. Therefore, the vibration can be measured by using a special imported bearing vibration measuring device (frequency analyzer, etc.). It is not possible to deduce the specific circumstances of the anomaly. The measured values ​​vary depending on the conditions of use of the bearing or the mounting position of the sensor. Therefore, it is necessary to analyze and compare the measured values ​​of each machine in advance to determine the judgment standard.

    Finally, it is checked according to the temperature of the imported bearing. The temperature of the imported bearing is generally estimated based on the temperature of the outdoor surface of the imported bearing. If the oil hole can directly measure the temperature of the bearing outer ring, it is more suitable.

    Usually, the temperature of the imported bearing rises slowly as the operation starts, and reaches a steady state after 1-2 hours. The normal temperature of the imported bearings varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the bearing temperature will rise sharply and abnormal temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions. Based on a large amount of test data, Table 4-1 lists the average value of the outer ring temperature when the bearings are working in various machines for reference. Since the temperature is affected by lubrication, speed, load, and environment, the values ​​in the table only indicate the approximate temperature range. The thermal sensor can be used to monitor the working temperature of the bearing at any time, and automatically alarm the household when the temperature exceeds the specified value or stop the occurrence of the burning shaft accident.

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Analysis of the causes of nine common faults

    It is not uncommon for the bearing to malfunction during operation, so there is no need to make a fuss. A failure has occurred and it is critical to judge and deal with it. Today we will explain the reasons for the common failure of FAG bearings.

1. The 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 the body of the mechanism is touched by hand, it should be normal to not feel hot, otherwise the bearing temperature is too high.

The reasons for the bearing temperature being too high are: the quality of the lubricating oil does not meet the requirements or deteriorates, the viscosity of the lubricating oil is too high; the assembly of the mechanism is too tight (the gap is insufficient); the bearing assembly is too tight; the bearing race rotates on the shaft or inside the casing; Large; bearing cage or rolling body fragmentation.

2. Bearing noise: The rolling bearing is allowed to have a slight running noise during operation. If the sound is too loud or there is abnormal noise or impact sound, it indicates that the bearing is faulty.

The reason for the noise generated by the rolling bearing: more complicated, 1) is the wear of the inner and outer rings of the bearing. As a result of this wear, the bearing and the housing, the bearing and the shaft are broken, causing the axis to deviate from the correct position and produce an abnormal sound when the shaft is moving at a high speed. When the bearing is fatigued, the surface metal peeling off will also increase the radial clearance of the bearing to produce abnormal noise. 2) Insufficient bearing lubrication, dry friction, and bearing crushing will produce abnormal sounds. 3) After the bearing wears loose, the cage is loose and damaged, and the abnormal bearing damage will also occur. When the rolling bearing is disassembled and inspected, the bearing failure and the cause of damage can be judged according to the damage of the bearing.

3. Metal peeling on the raceway surface: The rolling elements of the bearing and the raceway surfaces of the inner and outer rings are subjected to periodic pulsating loads, thereby generating cyclically varying contact stresses. When the number of stress cycles reaches a certain value, fatigue peeling occurs on the rolling element or the inner and outer ring raceways. If the bearing load is too large, this fatigue will be exacerbated. In addition, the bearing is not installed correctly, the shaft is bent, and the raceway is peeled off. Fatigue spalling of the bearing races reduces the accuracy of the shaft and causes vibration and noise in the mechanism.

4, bearing burns: burned bearings have tempering color on the raceway and rolling elements. The causes of burns are generally insufficient lubrication, the quality of the lubricant does not meet the requirements or deterioration, and the bearing assembly is too tight.

5. Plastic deformation: uneven pits appear on the contact surface between the raceway and the roller of the bearing, indicating that the bearing is plastically deformed. The reason for this is that under a large static load or impact load, the local stress of the working surface exceeds the yield limit of the material, which generally occurs on bearings rotating at low speed.

6. Bearing race crack: The cause of the crack in the bearing race may be that the bearing is too tight, the foreign or inner ring of the bearing is loose, the bearing of the bearing is deformed, and the surface of the bearing is poorly processed.

7. The cage is broken: the reason is insufficient lubrication, broken rolling elements, and skewed seat.

8. The metal of the cage adheres to the rolling elements. The possible reason is that the rolling elements are caught in the cage or insufficiently lubricated.

9. The raceway of the raceway is seriously worn: it may be that the seat is filled with foreign matter, the lubricant is insufficient or the lubricant grade is not suitable.

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Analysis of the causes of premature aging of rolling bearings

    Premature aging of rolling bearings will cause equipment to stop. Now we combine the author's motor maintenance practice to introduce the experience of preventing premature aging of rolling bearings. The reasons for premature aging of rolling bearings are: too tight, poor lubrication, misalignment, strong vibration, material fatigue, pollution and corrosion.

Tight fit

When the inner ring of the bearing is forcibly inserted into the journal, the lighter will cause a severely worn circular path at the bottom of the raceway, and the heavy one will have cracks or peeling on the inner and outer rings of the slideway and the ball. Reason: The gap between the ball and the slide is too small, the torque is increased, the friction is increased, and the working temperature of the bearing is too high, which causes the bearing wear and fatigue to deteriorate and fail.

Prevention method: Restore the radial clearance of the bearing and reduce the interference.

There are two ways to check the quality of bearing assembly:

Visual inspection method: When the bearing cover of the motor end cover is mounted on the bearing, when the end cover is rotated by hand, if the bearing rotates freely and flexibly, there is no vibration and shaking up and down, which is considered qualified.

The feeler gauge method: assemble the motor end cover with the bearing on the frame seat, and check the radial clearance of the bearing with a 0.03mm thick feeler gauge. If the maximum gap position is just above the center (motor horizontal installation) ), the assembly is correct and reliable, otherwise it is poorly installed. The end cap position should be properly adjusted and reassembled until it is qualified.

2. Poor lubrication

The reason is a serious lack of grease or dryness of the grease. Due to the high-speed running friction of the motor, the bearing temperature is too high and oxidative discoloration, which means that the ball, cage, inner ring and journal of the bearing become brown or blue.

Prevention method: According to the running time of the motor, the ambient temperature, the load condition, the quality of the grease, etc., determine the oil replenishment and oil change time. Under normal circumstances, the motor should be replenished once for 6000~10000h; the oil should be changed once for 10000~20000h, and the oil change of the motor with 2 or more poles is 1/2~2/3 of the bearing chamber volume, and High quality lithium grease (code ZL-2) should be used.

3. Installation is not aligned

If the installation is not centered, not only the bead marks on the bearing slides, but also the unevenness of the ball wear marks, and the deflection is also caused. When the radial clearance on both sides of the bearing is checked by the feeler gauge, the difference is large. The reason may be that the outer ring of the bearing is directly struck with the iron hammer; the belt is pulled too tight (the gear is engaged); the center line of the driving wheel and the driven wheel are not parallel. When the deflection is greater than 1/1000, the bearing running temperature is too high, the slide rail and the ball are seriously worn, the shaft bending and the end cap bolt pressing surface are not perpendicular to the bolt axis.

Proper installation method: Use a steel tube sleeve with a smooth end surface and almost the same thickness as the inner ring of the bearing to press the bearing in the correct position of the clean journal. The force should be even when pressed, not too strong. Then check the allowable yaw value of the radial end of the shaft according to the different speeds of the motor.

4. Strong vibration

When the motor core is faulty, the bearing will vibrate strongly. The reasons are: the iron core is deformed by heat; the motor bearing is aging; the bending deformation of the rotating shaft is large; the end cap tightening bolt is loosened due to vibration; the foundation is not strong and the bearing is vibrated.

Prevention method: the iron car is small, soak the surface of the silicon steel sheet and the gap opened with silicon organic varnish 1052; replace the new bearing of the same type; exit the bending part of the rotor core straightening shaft; adopt 180° symmetry method; tighten the end cover Bolt; reinforcement foundation, tighten anchor bolts.

5. Material fatigue

If the metal material fatigue, the bearing raceway and the irregular surface of the ball surface are mixed in the grease, the working noise will increase, the ball will slide, and the radial clearance of the bearing will increase, and the allowable diameter of the shaft end. Increase the yaw value by 2~3 times. The determinants of bearing fatigue include: motor load, speed, air gap, end cap type, material toughness, grease quality grease loading.

Prevention method: According to the motor operation record, when the light load working current is more than 60% of the rated value, run to 2000~25000h, the medium load working current is 60%~80% of the rated value, run to 15000~20000h, heavy load working current After running from 80% to 100% of the rated value to 10000~15000h, the normal fatigue of the bearing material should be considered and the new bearing of the same type should be replaced.

6. Pollution corrosion

At this time, red, brown spotted corrosion occurs on the surfaces of the raceways and balls, and the working noise is increased as compared with the sound of the new bearing.

The reason is that the assembly site is not clean, such as moisture, acid, alkali and toxic gases; tools and hands are contaminated; poor quality lubrication fingers are used.

Prevention method: The bearing should be kept clean by the environment, tools and equipment; the bearing should be clean thoroughly; replace the high-quality lithium grease.

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The essence of NSK bearing noise

For the use of bearings, it is very common to generate noise. Even the low-noise bearings in NSK bearings have the same situation. So why is there noise? Today I will introduce the essence to you.
    (1) Bearing track sound and its control method Rolling sound is a kind of slippery continuous sound that the rolling element rolls on the raceway surface when the bearing is running. It is the unique basic sound that all rolling bearings will produce. . The general bearing sound is the rolling sound plus other sounds. The ball bearing's raceway sound is irregular, the frequency is above 1000Hz, its main frequency does not change with the speed, but its total sound pressure level increases with the increase of the speed. For bearings with large rolling sounds, the sound pressure level of the raceway sound decreases with the increase of viscosity; while for bearings with small raceway sound, the sound pressure level decreases when the viscosity increases to about 20 mm2/s or more. For the increase. The greater the rigidity of the bearing housing, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and main frequency of the raceway sound will increase sharply as the radial clearance decreases. The method of controlling the rolling sound is to select a low-noise bearing, that is, a bearing with a small waviness, and carefully select the conditions of use. The raceway sound often affects the noise of the entire machine, and reducing the raceway sound can reduce the noise of the entire machine.
    (2) Impact sound of rolling element and its control method When the larger type of ball bearing or cylindrical roller bearing runs at low speed under pure radial load, the rolling element in the non-load area will be small due to the small centrifugal force of the rolling element. Noise is generated by impacting the cage or raceway. But as the speed increases, the sound will disappear. The control methods for the impact sound of the rolling element are: appropriately reducing the radial clearance, and using a bearing having a reasonable structure and a flexible material.
    (3) Bearing rolling sound and its control method Rolling sound is a harsh metal friction sound that can occur in cylindrical roller bearings in all occasions, most of which occur in grease-lubricated larger type bearings, and in base oil performance Deteriorated grease is more likely to occur and hardly occurs when oil is lubricated. In addition, it is more likely to occur in winter. When subjected to pure radial load, it is easy to occur in the case of large radial clearance, and it is easy to occur in a certain speed range depending on the size of the model, and it will occur continuously. It will appear intermittently. Special processing methods for the outer ring raceway can prevent the occurrence of rolling noise. If necessary, the bearing can be selected, or the radial clearance of the bearing can be appropriately reduced, and the grease with excellent performance and the rigidity of the bearing device can be improved.

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Cage material and heat treatment

When the bearing is working, especially at high speeds, the cage is subjected to large centrifugal forces, impact and vibration, large sliding friction, and generates a large amount of heat. Therefore, the material is required to have good thermal conductivity, good wear resistance, small friction coefficient, small specific gravity, a certain strength, a coefficient of expansion close to the rolling element, and good processing performance. Special purpose bearing cages also have special requirements, such as high temperature resistance. Currently commonly used cage materials are high quality low carbon steel (08, 10, 08F, 10F), brass, stainless steel, spring steel, alloy steel, phenolic tape, plastic and so on.

    The heat treatment of the cage is mainly used for stamping cages, mostly for heat treatment between processes, so that the material can be restored to plasticity, which will cause severe work hardening and internal stress during the processing of the cage. Such heat treatments include: recrystallization annealing of high-quality carbon sheet steel cold stamping cage (heating to about 600 ° C, heat preservation for 2 to 3 h, furnace cooling); recrystallization annealing of brass strip cold stamping cage (heating to 600-650 ° C, Insulation for 30 min, air or water cooling); stainless steel with cold stamping softening treatment.

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Lubrication methods and advantages and disadvantages of rolling bearings

Lubrication methods and advantages and disadvantages of rolling bearings
    1. Purpose of lubrication
    The purpose of lubrication of rolling bearings is to reduce internal friction and wear of the bearings and prevent burn-in. The lubrication effect is as follows:
    1) Reduce friction and wear
    In the mutual contact portion of the ferrule, the rolling element and the cage constituting the bearing, metal contact is prevented, and friction and wear are reduced.
    2) Extend fatigue life
    The rolling element fatigue life of the bearing is prolonged when the rolling contact surface is well lubricated during rotation. Conversely, if the oil viscosity is low and the thickness of the lubricating oil film is not good, it is shortened.
    3) Eliminate friction heat and cooling
    The circulation oil supply method or the like can discharge the heat generated by the friction or the heat from the outside to cool the oil. Prevent the bearing from overheating and prevent the lubricant from aging itself.
    4) Other
    There is also the effect of preventing foreign matter from entering the inside of the bearing or preventing rust and corrosion.
    2, lubrication methods and advantages and disadvantages
    The lubrication methods of the bearings are grease lubrication and oil lubrication. In order to make the bearing function well, first, choose a lubrication method that suits the conditions of use and the purpose of use. Lubricity of oil lubrication predominates if only lubrication is considered. However, grease lubrication has the advantage of simplifying the structure around the bearing.

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Surface treatment of bearings with diamond coating reduces loss

Bearings are a universal part, and only a few equipments do not use bearing designs. In most cases, bearings are found in all types of instruments and equipment systems. Surface treatment of ball and plain bearings with a diamond-type coating can greatly reduce the frictional losses of the bearing system. In advance, this diamond-type coating can be applied to plastic bearings through a special coating process to improve the durability of components and extend the life of the equipment.

    Ball bearings are often seen in the transmission section of bicycles, while plain bearings can be found in the shaft of a ship. Bearings play a vital role in many drive and brake designs. They not only work well under high-speed engines and high-heat composite conditions, but also help materials meet the requirements of some extremely demanding working environments. Diamond-type coatings The emergence of the application is very good.

    Scientists from the IWM Materials Performance Research Center in Freiburg, Germany, are actively developing new generations of bearings for the next generation. They have developed a special high-performance chemical coating for the bearings to provide a smooth surface in the bearing. Degree, reduce friction, so as to achieve the design requirements to extend the purpose of bearing use. These innovative coating products, mainly composed of diamond-type carbon (DLC), said Dr. Sven Meier, head of the research center, "The emergence of diamond-based coatings has given us a strong technology for future bearing design. Support. We are fully capable of designing new products that last longer than conventional bearings. The bearing technology and applications for this new coating are still under development, and we envisage that this product can be used without lubricants. The situation can be done well."

    Of course, the surface treatment of diamond coatings on bearings also requires special coating processes, and IWM scientists have also completed the development of this process. Meier went on to say, “Our coating method can be used for surface treatment of complex geometric components such as bearing cages.” Engineers are currently optimizing this technology to achieve low-coat thickness performance. Application requirements, it is reported that IWM plans to control the coating thickness below 20 microns. “Our process ensures the coating service requirements for micron-sized coating structures. At this size, the coating can completely replace traditional lubricants or lubricants to minimize system friction. Special requirements can also create super smooth material surfaces."

    Currently, researchers are further developing coating coating processes to ensure they meet the specific requirements of different sizes and shapes. IWM's goal is to reduce the high cost of existing bearing processing by optimizing the process, thereby reducing the cost of enterprise equipment procurement and equipment maintenance.

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