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Precision

The precision of a spindle ball bearing does affect the guiding properties as well as lifetime, especially with applications at max. speed.
The tolerances for dimensional, form and running accuracy of GMN high precision ball bearings are specified in international (ISO 492) and national standards (DIN 620). GMN high precision bearings are manufactured to precision class 4 and class 2 (P4 and P2) as well as ABEC 7 and ABEC 9 (according to ABMA). For special applications, e.g. vacuum pumps, gyroscopes as well as measuring engineering and optical systems, GMN manufactures bearings to the internal tolerance classes HG (high precision) and UP (ultra precision). Apart from the requirements mentioned, the tolerance classes contain additional selection criteria. The relationship between the various standards are explained below. 

ISO	DIN	ABMA
class 4	P4	ABEC7
class 2	P2	ABEC9

 

All GMN spindle ball bearings according to tolerance class P4 or ABEC 7 correspond (without further description) to precision class P4S according to DIN 628-6. I.e. the tolerances correspond to precision class P2 with regard to radial and axial runout. The dimensional and form accuracy correspond to precision class P4 or ABEC 7.
Moreover GMN offers its own factory precision classes HG (high precision) and UP (ultra precision). These have partly stricter tolerances than precision class P2. (See on this catalogue pages 16/17 or download tolerances or contact our technical support.)