ISO 286-2:2010 pdf free download – Geometrical product specifications (GPS)- Iso code system for tolerances on linear sizes一 Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts.
For more detailed information on the relationship of this part of ISO 286 to the GPS matrix model, see Annex B.
The need for limits and fits for machined workpieces was brought about mainly by the requirement for interchangeability between mass-produced parts and the inherent inaccuracy of manufacturing methods, coupled with the fact that “exactness” of size was found to be unnecessary for most workpiece features. In order that the fit function could be satisfied, it was found sufficient to manufacture a given workpiece so that its size lay within two permissible limits, i.e. a tolerance, this being the variation in size acceptable in manufacture while ensuring the functional fit requirements of the product.
Similarly, where a specific fit condition is required between mating features of two different workpieces, it is necessary to ascribe an allowance, either positive or negative, to the nominal size to achieve the required clearance or interference. ISO 286 gives the internationally accepted code system for tolerances on linear sizes. It provides a system of tolerances and deviations suitable for two types of feature: “cylinder” and “two parallel opposite surfaces”. The main intention of this code system is the fulfilment of the function fit.
The terms “hole”, “shaft” and “diameter” are used to designate the types of feature of cylinders (e.g. for the tolerancing of the diameter of a hole or shaft). For simplicity, they are also used for two parallel opposite surfaces (e.g. for the tolerancing of the thickness of a key or the width of a slot).
This part of ISO 286 gives values of the limit deviations for commonly used tolerance classes for holes and shafts calculated from the tables given in ISO 286-1. This part of ISO 286 covers values for the upper limit deviations ES (for holes) and es (for shafts), and the lower limit deviations El (for holes) and ei (for shafts) (see Figures 1 and 2).
NOTE In the tables of limit deviations, the values of the upper limit deviation ES or es are shown above the values of the lower limit deviation El or el except for tolerance classes JS and js which are symmetrical about the zero line.
The ISO system for tolerances on linear size provides a system of tolerances and deviations suitable for features of the following types:
a) cylinders;
b) two parallel opposite surfaces.
For simplicity, and also because of the importance of cylindrical workpieces of circular section, only these are referred to explicitly. It should be clearly understood, however, that the tolerances and deviations given in this part of ISO 286 equally apply to workpieces of other than circular sections.
In particular, the term “hole” or “shaft” is used to designate features of the cylinder type (e.g. for the tolerancing of the diameter of a hole or shaft) and, for simplicity, these terms are also used for two parallel opposite surfaces (e.g. for the tolerancing of the thickness of a key or the width of a slot).
For further information on terminology, symbols, the basis of the system, etc., see ISO 286-1.