High Precision Ball Bearings - Kraftmek

Radial runout
Meeting the radial runout of the inner and outer ring,
specified in the various standards, is 100% controlled.
On request the highest point (max wall thickness) is
marked by a point on the face. This is an additional help
for the user to minimise wobble.
Matching accuracy
The matching accuracy of ± 2 microns for a single
bearing ensures a uniform load distribution and a uniform
operating temperature within the series. GMN offer
bearing pairs with increased matching accuracy
(± 1 micron) on request. When specifying the type of
matching, like DB, DF or DT for pairs or groups matching
takes place to an optimum for precision class HG and
up.
Grading
When two or more matched bearings carry a load
together the bore and outside diameter should be
identical. Due to the selective pairing of bore and outside
diameter the fitting on the shaft and in the housing are
facilitated. On special request GMN grades the tolerances
of bore and outside diameter. The suffix here to is "X".
Tolerances smaller than 3 microns are not graded. The
grading groups can, for practical reasons, only be
selected, but not manufactured separately.
The groups are marked on the box as follows:
Grade Bore Outer diameter
X11 O O
X12 O U
X21 U O
X22 U U
X10 O –
X20 U –
O = Upper tolerance half
– = No grading
U = Lower tolerance half
O
U
O
U
20