BS ISO 1328‑2:2020 pdf download.Cylindrical gears — ISO system of flank tolerance classification.
Additional information on double flank testing is given in ISO/TR 10064-2.
NOTE I Tolerances for a specified class are calculated according to the formulae in Clause 5. To aid in visualizing how the tolerances change with the number of gear teeth, graphs are provided in Annex A showing tolerance values for 3 tolerance classes.
NOTE 2 There is no correlation or interrelation between the classes specified in this document and other parts or standards such as ISO 1328.1. This document uses a unique set of tolerance classes (i.e., R30 to R50) to reinforce that no correlation to other elemental or radial composite standards exists (see Anne&C). However, while there is no general correlation to other standards, for a specific gear it is possible to find a tolerance class or classes according to this document that will give similar tolerances to those that were originally specified for the gear, see AnnxD.
NOTE 3 The specific methods of measurement, documentation of the results, inspection frequency, and use of statistical methods are items that normally are mutually agreed upon between the manufacturer and the purchaser.
4.2 Gear tooth tolerance class
In this document, the double flank radial composite tolerance class is determined by measurement of total radial composite deviation, Fd, and tooth-to-tooth radial composite deviation, lid. A gear that is specified to a single ISO double flank radial composite tolerance class shall meet both individual tolerance requirements.
In addition to the total and tooth-to-tooth tolerances, Annex B provides an optional specification for composite tolerance over a selected number of teeth, k.
NOTE 1 Specifying a class or measurement criteria that require more precise tolerances than required by the application can unnecessarily increase the cost.
NOTE 2 Double flank measurements, such as tight mesh center distance, can he used for control of tooth thickness and total radial composite effects simultaneously.
This document allows for the specification of separate classes for total radial composite deviation, F1d, and tooth-to-tooth radial composite deviation, lid.
The assessment of the gear’s double flank radial composite tolerance class shall be performed after the final manufacturing process. Double flank composite checks may also be performed at any step in the manufacturing process.
This document is for classes R30 to R50. It may be convenient in a specific application to use the formulae in this document by extrapolating them below R30 or beyond R50. When this is done. individual tolerances should be Lised on these applications as opposed to defining a class outside of the R30 to R50 range.
4.3 Specification of datum surfaces
Specification of radial composite tolerances requires the definition of datum surfaces to be used for double flank inspection. See ISO/TR 10064-3.BS ISO 1328‑2 pdf download.