scope:

This part of ISO 1328 establishes a tolerance classification system relevant to manufacturing and conformity assessment of tooth flanks of individual cylindrical involute gears. It specifies definitions for gear flank tolerance terms, the structure of the flank tolerance class system, and allowable values. This part of ISO 1328 provides the gear manufacturer and the gear buyer with a mutually advantageous reference for uniform tolerances. Eleven flank tolerance classes are defined, numbered 1 to 11, in order of increasing tolerance. Formulae for tolerances are provided in 5.3. These tolerances are applicable to the following ranges: 5 ≤ z ≤ 1 000 5 mm ≤ d ≤ 15 000 mm 0,5 mm ≤ mn ≤ 70 mm 4 mm ≤ b ≤ 1 200 mm β ≤ 45° where d is the reference diameter; mn is the normal module; b is the facewidth (axial); z is the number of teeth; β is the helix angle.