Bore and O.D. Coding
To better match machine tool bearings to spindles, Torrington currently offers Bottom/Top bore and O.D. coding as standard for angular contact superprecision bearings.
The code is a mark on the box label with the bore code shown above the O.D. code. The tolerances are split in half as shown in the figure below. If the bore and O.D. sizes fall in the half closest to nominal, this is
considered the top half and the set will be marked with a T/T. With a T/T code, the bore and O.D. tolerances would meet ABEC 9 requirements. If the bore and O.D sizes fall in the half farthest from the nominal, this is considered the bottom half and the set will be marked with a B/B. If the bore is in the top half and O.D. is in the bottom half, the set will be marked T/B and vice versa B/T.
TOTAL O.D. TOLERANCE
TOTAL BORE TOLERANCE
BOTTOM/TOP BORE & O.D. CODING
NOMINAL O.D. DIMENSION
NOMINAL BORE DIMENSION
Offering bore and O.D. coding makes it easier to obtain the optimum recommended fits for spindles. Each bearing in a set is matched to within half the bore and O.D. tolerance to insure equal load sharing. It also
enables our customers to use pairs of bearings with same bore and O.D. codes to make triplex and quadruplex sets.