scope:

This information sheet establishes a tolerance classification system relevant to manufacturing and conformity assessment of tooth flanks of a single piece rack. It specifies definitions for rack flank tolerance terms, the structure of the flank tolerance class system, and allowable values.

This document provides the manufacturer and purchaser with a mutually advantageous reference for uniform rack tolerances. Twelve flank tolerance classes are defined, numbered V3 to V14, in order of increasing tolerance. For composite measurements, twenty tolerance classes are provided, numbered R31 through R50 in order of increasing tolerance. Equations for tolerances are provided in 6.5. These tolerances are applicable to the following ranges:

3 mm ≤ L_R ≤ 3500 mm

0.5 mm ≤ m_n ≤ 70 mm

4 mm ≤ b ≤ 300 mm

β ≤ 45°

where

L_R is the rack length;

m_n is the normal module;

b is the face width;

β is the helix angle.

The measurement methods and tolerances are applied to a rack in the fixtured state that replicates the rack application.

Exclusions

Rack design is beyond the scope of this information sheet.

Surface texture is not considered in this information sheet. For additional information on surface texture, refer to ISO/TR 10064-4 [1].