Precision bearings require

Due to the precise accuracy of the bearing itself within in the 1 μ m, so go with parts (shafts, housings, cover, retaining ring, and so on) has a high dimensional accuracy and precision, especially with accuracy and bearing the same level of control, which is crucial, and also the most easily overlooked.

Must also pay attention to the precision bearings matched parts if you do not meet these requirements, often makes precision bearings after installation several times larger than the original bearing error occurred, or even more than 10 times the error, completely not precision bearings due to mechanical error is often not simply to match is superimposed on the bearing's error, but by multiples of different magnification added.