Common reasons for bearing noise are as follows

Update:2018-10-27

Common reasons for Tilting pad journal bearing noise are as follows
NTN bearing is noisy (caused by the end face of the roller or the slip of the steel ball);
 The fit between the NTN bearing and the shaft is too loose (the diameter of the shaft is too small or the adapter sleeve is not tightened);
 The shoulder is too large (touching the seal of the NTN bearing and rubbing);
 The shoulder of the seat hole is too large (the seal of the NTN bearing is distorted);
The gap of the labyrinth seal is too small (friction with the shaft);
The teeth of the lock washer are bent (touching the NTN bearing and rubbing);
 The position of the oil ring is not suitable (the flange cover is encountered and friction occurs);
There is a pressure pit on the steel ball or roller (caused by hammering NTN bearing when installing);
NTN bearings are noisy (with external source interference);
The NTN bearing is discolored and deformed by heat (caused by the use of a spray gun to disassemble the NTN bearing);
The shaft is too thick to make the actual fit too tight (causing the NTN bearing temperature to be too high or noise);
NTN bearings are noisy (NTN bearings have fretting abrasion).
 NTN bearing housing hole diameter is too large, the actual fit is too loose (NTN bearing temperature is too high - outer ring slip);
 NTN bearing housing hole becomes larger (NTN bearing housing hole of non-ferrous metal is enlarged, or becomes larger due to thermal expansion);
The diameter of the seat hole is too small (causing the NTN bearing temperature to be too high).