After the installation of NTN bearing, in order to check whether the installation is correct, Inspection Items operation inspection shall be carried out. Small machinery can be rotated by hand to confirm whether it rotates smoothly.
The inspection items include poor operation caused by foreign matters, scars and indentation, unstable torque caused by poor installation and poor processing of mounting base, excessive torque caused by too small clearance, installation error and sealing friction, etc. If there is no abnormality, the power operation can be started.
Large machinery cannot rotate manually, so the power shall be cut off immediately after no-load start, and the machinery idles. Inspection Items Check whether there is vibration, noise, contact of rotating parts, etc. after confirming that there is no abnormality, enter the power operation.
Power operation, starting from no-load and low speed, slowly increase to the rated operation under the specified conditions. Inspection Items During the test run, the inspection items are whether there is abnormal sound,
NTN bearing temperature change, lubricant leakage or discoloration, etc. If any abnormality is found, stop the operation immediately Inspection Items and check the machinery. If necessary, remove the NTN bearing for inspection.
However, it is more accurate to directly measure the temperature of NTN bearing outer ring with oil hole. The temperature of NTN Inspection Items bearing increases gradually from the beginning of operation, and the temperature is usually stable after 1 ~ 2 hours.
If the NTN bearing is not installed properly, the temperature will rise sharply and abnormal high temperature will occur. The Inspection Items reasons are too much lubricant, too small NTN bearing clearance, poor installation, excessive friction of sealing device, etc.
In the case of high-speed rotation, the wrong selection of NTN bearing structure and lubrication mode is also the reason.
The rotating sound of NTN bearing is checked with stethoscope, and there are strong metal noise, abnormal sound, irregular sound and other abnormalities. The reasons include poor lubrication, poor accuracy of shaft or NTN bearing seat, NTN bearing damage, foreign matter intrusion, etc.
The sound detector is used to check the size and sound quality of the rolling sound of the running Timken bearing. Even if there is slight peeling and other damage, the Timken bearing will produce abnormal sound and irregular sound, which can be distinguished by the sound detector.
It is a common method to use hearing to identify irregular operation. For example, it is often used by experienced operators to detect the abnormal noise of a part with the help of an electronic stethoscope.
If Timken bearing is in good continuous rotation state, it will make a low whine sound. If it makes sharp hiss, squeaks and other irregular sounds, it often indicates that Timken bearing is in poor continuous rotation condition.
Sharp squeaking noises may be caused by improper lubrication. Improper Timken bearing clearance can also cause metallic sound.
Dents in the concave track on the outer ring track of Timken bearing will cause vibration and cause a smooth and crisp sound. If the knocking scar caused by installation will also produce noise, the noise will vary with the speed of Timken bearing.
If there is intermittent noise, it indicates that the rolling parts may be damaged. This sound occurs when the damaged surface is rolled out. If there are pollutants in Timken bearing, it will often cause hissing sound. Serious damage to the bearing will produce irregular and loud noise.
Timken bearing damage can be detected by hearing, but usually it is time for Timken bearing to be replaced immediately. Therefore, it is better to use, for example, electronic condition monitoring instruments. The Timken bearing condition can be estimated more accurately by using a wooden stick than the old method.