1. The limit speed of NTN bearing
The speed of NTN bearing is mainly limited by the temperature rise caused by the friction heating inside the bearing. When the speed exceeds a certain limit, the bearing will not continue to rotate due to burns.
The limit speed of NTN bearing refers to the limit value of the speed at which it can rotate continuously without generating frictional heat that causes burns.
Therefore, the limit speed of NTN bearings depends on various factors such as the type, size and accuracy of the bearing, the lubrication method, the quality and quantity of the lubricant, the material and type of the cage, and the load conditions.
The limit speeds of various NTN bearings using grease lubrication and oil lubrication (oil bath lubrication) are listed in each bearing size table. The value represents the limit value of the speed when the standard design bearing rotates under the general load condition (C/P≥13, Fa/Fr≤0.25).
In addition, depending on its type and brand, lubricants may be superior to other properties but not suitable for high-speed rotation.
2. Correction of NTN bearing limit speed
Load condition C/P<13 (that is, the equivalent dynamic load P exceeds about 8% of the basic dynamic load rating C). Or when the axial load in the combined load is more than 25% of the radial load, the speed limit must be corrected with the following formula.
na= f1 ∙ f2 ∙ n
among them:
na: revised limit, rpm
f1: correction factor related to load conditions
f2: The correction factor related to the composite load
n: limit speed under general load conditions.rpm
C: Basic dynamic load rating, N {kgf}
P: equivalent dynamic load, N{kgf}
Fr: radial load, N{kgf}
Fa: Axial load, N{kgf}
3. Precautions for high-speed rotation
When NTN bearing rotates at high speed, especially when the rotating element approaches or exceeds the limit speed recorded in the dimension table, the following matters should be paid attention to:
(1) Use NTN precision bearings
(2) Analyze the internal clearance of NTN bearings (considering the internal clearance of the bearing caused by temperature rise, call a small amount)
(3) Analyze the type of cage material (for high-speed rotation, copper alloy or phenolic resin cutting cage is suitable. In addition, there are also synthetic resin molded cages suitable for high-speed rotation)
(4) Analyze the lubrication method (using circulating lubrication, jet lubrication, oil mist lubrication and oil-air lubrication suitable for high-speed rotation)
(5) Use phenolic resin to cut the cage. In addition, there are also synthetic resin molded cages suitable for high-speed rotation) analytical lubrication methods (using circulating lubrication, jet lubrication, oil mist lubrication and oil-air lubrication suitable for high-speed rotation. NTN 4T-30203 bearings online , pls click here :
NTN bearing installation environment is very important (14% are polluted)
The installation quality is of vital importance to the use of NTN bearings. Therefore, we need to do some preparatory work before bearing installation. According to statistics, it is known that 14% of the bearing pollution is due to the failure of pre-installation preparations. Caused by good, such as: environmental problems.
The NTN bearing installation environment is very important. It must be installed in a dry and clean environment for NTN bearings to operate better.
In order to let everyone know more about the preparations for bearing installation, Eric Bearing Limited, based on the understanding of bearing knowledge, shares some matters before bearing installation:
1. According to different NTN bearing size and application environment, adopt different installation methods;
2. Prepare the necessary components, tools and equipment for installation;
3. Prepare all the parts that need to be installed and clean them thoroughly before installation;
4. Check the size and shape accuracy of all parts to be installed according to the drawings.
Note: When installing NTN bearings, do not unpack the NTN bearings before the preparation work is completed to avoid contamination of the bearings.
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