How To Choose NTN Bearing Type
Usually the space where NTN bearings can be installed is limited. In most cases, the shaft diameter is based on mechanical restrictions or other design restrictions. Therefore, the choice of bearing type and size is determined according to the inner diameter of the bearing. Therefore, the main dimension tables of standard NTN bearings are compiled according to the international standard inner diameter dimensions.
There are many sizes of standard NTN bearings. It is best to use standard bearings in the design of mechanical devices. Bearings are not available in mainland China, and sometimes the futures will take a long time, so the time cost and the cost of later replacement should be considered when selecting the bearing) The load of the bearing, the load imposed on the bearing, its nature, size and direction are Changing. Usually, the rated basic load is shown on the dimension table. But axial load and radial load are also important factors in choosing a suitable NTN bearing. When the size of the ball and needle bearings is equivalent, the needle bearings usually have a higher load capacity and bear larger vibration and shock loads.
The allowable speed is determined by factors such as NTN bearing type, size, accuracy, cage type, load, lubrication method, and cooling method. The bearing table lists the allowable speed of standard precision bearings under oil lubrication and grease lubrication. Generally, deep groove ball bearings, self-aligning ball bearings and cylindrical roller bearings are suitable for high-speed operation.
NTN bearing dimensional accuracy and rotation accuracy are based on ISO and JIS standards. For machines that require high precision and high-speed operation, it is recommended to use bearings of grade 5 or higher accuracy. Deep groove ball bearings, radial thrust ball bearings or cylindrical roller bearings are suitable for machines with high running accuracy. Rigidity, when the rolling element of the bearing and the contact surface of the raceway are compressed, elastic deformation will occur. Some machines need to minimize elastic deformation. Roller bearings produce less elastic deformation than ball bearings.
In addition, in some cases, NTN bearings have to be preloaded to increase rigidity. This procedure is usually used for deep groove ball bearings, radial thrust ball bearings and tapered roller bearings, inner and outer ring offset, shaft bending, shaft or bearing box tolerance changes, fit errors will cause eccentricity of the inner and outer rings. In order to prevent the eccentric angle from being too large, self-aligning ball bearings, self-aligning roller bearings, or self-aligning bearing seats are the better choices. Voice frequency and torque, rolling bearings are manufactured according to high precision standards, so the voice and torque are small. Deep groove ball bearings and cylindrical roller bearings are suitable for occasions with special requirements for low noise and low torque.
Installed separately such as: cylindrical bearings, needle roller bearings, and tapered bearings are very suitable for this occasion. The tapered bore type self-aligning ball bearings and self-aligning roller bearings also simplify the installation procedure with the help of the bushing.
(1) Before the NTN bearing is installed, the processing quality of the shaft and the seat hole and related parts (such as dimensional accuracy,shape accuracy and surface roughness, etc.).
(2) If there are bruises, burrs, rust spots or solid particles (such as abrasive debris, sand, mud) on the assembly surface of the shaft and bearing housing holes, not only will the bearing installation be difficult and the installation position is incorrect, but also solid If the particles fall into the NTN bearing, they will be abrasive. When the NTN bearing rotates, it will abrade or scratch the working surface of the NTN bearing, so it must be carefully checked before installation. If the above defects are found, they should be corrected. For example, use an oil file to remove burrs, bumps, rust spots, and polish with a fine emery cloth, such as cleaning solid particles and dirt.
(3) The assembly surface should be cleaned with a clean solution of gasoline, kerosene, toluene or xylene, and wiped dry with a clean cloth, and then coated with a thin layer of lubricating oil, so that the installation operation is more convenient.
(4) Open the bearing package immediately before installation, immerse it in the above-mentioned gasoline and other liquids and slowly turn it by hand, to ensure that the sealing oil on the surface of the cage, rolling elements and raceway is thoroughly cleaned.
(5) When cleaning a large number of NTN bearings, first use hot engine oil at a temperature of 90-100 ℃ to drench the package oil, and use a seamless and non-chip tool to dig out all the old oil and then drench it for a few minutes. , Then rinse off the engine oil with kerosene, and finally clean it again with gasoline. After cleaning, wear film gloves and put the bearing on a clean cloth or paper on the work table to dry.