Writer: Eric Bearing Limited
NTN bearing lubrication is best implemented during the planned equipment downtime and is regularly replenished. At the same time, the old grease is removed or the old grease is squeezed out through the oil drain. Wipe the grease nipple clean before adding fresh grease. If the bearing housing of the thrust ball bearing does not have a grease nipple, the bearing housing cover or end cover should be opened to remove the old grease, and after cleaning, add fresh grease of the same model.
In order to ensure the normal operation of NTN bearings, we need to regularly check the oil level and quality of the lubricating oil. Under normal circumstances, the normal oil level should be within the range of the equipment oil level window or the marked 1/3-2/3. The oil replenishment method is the oil cup. The oil level displayed only represents the oil replenishment capacity, while the oil level of the bearing box meets the operating requirements. The oil level in the oil cup is less than 1/4 of its total volume.
1. Low-temperature high-speed bearing grease
At present, the equipment using thrust ball bearings is becoming more and more refined, and the grease used in the bearings must have the following properties:
(1) It has the same operating life as the bearing, as long as possible to extend the maintenance cycle, shorten the downtime, and improve labor productivity.
(2) At a high speed of dn>5×105, it is necessary to ensure that the temperature rise of the motor is low and oil is not thrown away, thereby reducing power consumption and protecting the motor.
(3) The impurity content is controlled below a certain standard to minimize the pollution of equipment noise to the environment.
(4) Under the ultra-low temperature working conditions, the flexibility of starting and running of the bearing is ensured, and the minimum output power is guaranteed.
2. General low noise motor bearing grease
In the NTN bearing industry, the application of this type of grease is the largest, accounting for about 70% of the total grease consumption. Because this type of grease uses soft soap and easy to filter lithium soap as a thickening agent, and uses mineral oil as the base oil, it is easy to meet the requirements of lower and middle thrust ball bearings to reduce vibration values. Another advantage is that it has good pumpability, whether it is mechanical grease or manual grease, it is simple and easy.
3. High temperature, long life, low noise bearing grease
The grease used in high temperature and high speed environment should have the following characteristics:
(1) It does not run off at high temperature, that is, it maintains a certain consistency at a temperature of about 180°C and does not soften.
(2) Less oil leakage. When the grease is subjected to high frequency repeated shearing and a large centrifugal force in the bearing, the lubrication can be returned to the raceway in time without being thrown out.
(3) It has a certain mute effect. Since the fiber of high-temperature grease is generally harder, the mute performance in the thrust ball bearing noise test is far inferior to that of lithium-based grease.
(4) This type of grease must have a certain high-temperature service life and good oxidation resistance at high temperatures, thereby extending the life of NTN bearings and related equipment.
Use an oil-bath 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 60-100°C (140-210°F), the lubricant needs to be changed four times a year. If the oil temperature is between 100-120°C (210-250°F), the lubricant needs to be changed once a month. If the oil temperature is above 120°C (250°F), the lubricant needs to be changed once a week.
Correct installation and maintenance are important factors for the normal operation of NTN bearings. At the same time, care must be taken to maintain the cleanliness of thrust ball bearings. Bearings must be protected from contaminants and moisture, and must be properly installed and lubricated. In addition, the design of the bearing arrangement, the condition of the oil seal, the form of the lubricant and the replacement cycle and special maintenance also play an important role and must be paid attention to. NTN 6205 LLU bearings online , pls click here :
NTN bearing use technology repair method
NTN bearings are mass-produced mechanical parts, and the manufacturing precision is very strict, and the degree of technical specialization is very high. Therefore, for most types of bearings that are easy to buy, it should be more cost-effective to buy than repair, only in the following cases Next, consider the problem of bearing repair, namely:
(1) A large number of bearings of the same type used in large factories are mainly in the form of rolling surface wear, fatigue or fretting abrasion, especially the damaged parts are mostly cages or rolling elements, and the ferrules or washers are still repaired value;
(2) Large-scale and extra-large bearings, which are on the verge of failure or have failed but there is no major damage to the parts, or valuable NTN bearings must try to extend their effective life;
(3) Some types of bearings that are really difficult to purchase, have to be repaired without spare parts after failure, especially imported bearings;
(4) There is slight damage to the bearing, such as slight rust generated during the inventory period, and slight fretting abrasion generated during transportation. It is a pity to repair such cases easily.
In addition to economics, the repair of NTN bearings also has its technicality, which requires the repairer to fully understand the corresponding technical requirements of the bearing, and the characteristics of the bearing and its parts in structure, process and material, otherwise it is difficult to guarantee bearing repair Has a satisfactory effect.
In the business of repairing bearings, if users can obtain the cooperation of professional bearing companies, they may get the following benefits:
(1) It is possible to clarify the technical requirements of each repair process and how to ensure the overall quality of the repaired bearings,
(2) Many specialized experiences of professional bearing factories can be used, which can reliably, efficiently and economically meet process requirements;
(3) It is possible to order tooling die from professional bearing enterprises and borrow it for repair business, which may be more economical and save a lot of trouble;
(4) Accessories such as cages, rolling elements, rivets, etc. can be ordered from professional bearing companies, which may make repair work simple, convenient, and economical.
If the NTN bearing is installed on the adapter sleeve, determine the direction of the bearing seat. The grease nipple of the bearing housing top cover should always be on the other side of the adapter sleeve nut. Attention must be paid to the direction of the entire bearing seat, because the top cover and base must be installed in the original direction.
1. The installation and disassembly of bearings will sometimes be involved; the movement of heavy objects, the use of tools and other equipment, or the use of high-pressure oil.
2. Make sure the environment is clean.
3. Check the dimensional and shape tolerances of the journal.
4. Check that the surface roughness Ra of the supporting surface is not greater than 12.5 μm. The flatness tolerance should be IT7. For less demanding applications, IT8 is available.