Overview
ISO 286-1:2010 - part of the Geometrical Product Specifications (GPS) family - establishes the ISO code system for tolerances on linear sizes. It sets out the basic concepts, terminology and coding rules used to specify tolerances and fits for two feature types: cylinders (e.g., holes and shafts) and two parallel opposite surfaces (e.g., slots, keys). ISO 286-1:2010 defines how limit deviations and tolerance classes are named, read and selected to achieve required functional fits between mating parts.
Key topics and technical requirements
- Scope and feature types: applies to cylinders and two parallel opposite surfaces used as features of size.
- Core terminology: defines nominal size, actual size, limits of size (ULS/LLS), deviation, fundamental deviation, tolerance and tolerance interval.
- ISO code system: describes the composition of a tolerance class (fundamental deviation letter + standard tolerance grade, e.g., h9, IT7) and the writing/reading rules for class designation.
- Limit deviations and placement: explains upper/lower limit deviations (ES/EI for holes, es/ei for shafts), and how these establish the position of the tolerance interval relative to nominal size.
- ISO fit system: gives the basic method to determine fits (clearance, interference, transition) between mating features and explains the principles of basic hole and basic shaft. The precondition is identical nominal sizes for hole and shaft.
- Selection guidance: provides standardized selection of commonly used tolerance grades and guidance on choosing tolerance classes for general purposes.
- Interaction with other GPS rules: notes the change in size association criterion (ISO 14405-1) from the envelope to the two‑point criterion and advises when form tolerances or envelope control may be needed to ensure intended function.
Practical applications and users
ISO 286-1:2010 is essential for:
- Mechanical and design engineers specifying dimensional tolerances and fits in drawings and CAD models.
- Manufacturing engineers selecting tolerances for machining, turning, broaching, grinding and quality processes.
- Quality, metrology and inspection teams interpreting limits of size, measuring parts and verifying conformity.
- Procurement and supply chain professionals ensuring interchangeability and component compatibility.
Typical applications include shafts and holes for bearings, pins and bores, keyed shafts, dowel assemblies, and general mass production where functional fits and interchangeability matter.
Related standards
- ISO 286-2: Tables of standard tolerance grades and limit deviations for holes and shafts (complements Part 1).
- ISO 14405-1: Dimensional tolerancing - Linear sizes (association criteria and size definition).
- ISO 14660-1 / -2: GPS general terms and definitions relevant to features of size.
ISO 286-1:2010 provides the conceptual backbone for specifying linear size tolerances and fits, enabling consistent, internationally accepted tolerance communication across design, production and inspection.