| IT Grade(s) | Precision Level | Typical Applications | |-------------|----------------|----------------------| | IT01 – IT0 | Ultra-High Precision | Optical flats, aerospace tooling, semiconductor manufacturing | | IT1 – IT4 | Extremely Precise | High-accuracy measuring instruments, slip gauges, scientific optics | | IT5 | Very High Precision | Precision machine tool spindles, high-precision gears | | IT6 – IT7 | High Accuracy | Bearings, hydraulic components, engine crank mechanisms | | IT8 – IT9 | Medium Precision | Low-precision transition fits, general machinery | | IT10 – IT13 | Loose Precision | General turning, non-critical assemblies | | IT14 – IT18 | Very Loose | Castings, forgings, coarse manufacturing processes |
When a shaft is mated with a hole, the combination of their specific tolerances determines the "fit." ISO 286 categorizes these into three types:
A group of tolerances that vary according to the nominal size but provide a consistent level of manufacturing accuracy. It is represented by a number. Decoding the ISO 286 Alphanumeric System
Understanding ISO 286: The Definitive Guide to the Geometrical Product Specifications System iso 286 pdf
Remember: ISO 286 is not just a document; it is a language. Once you can read Ø25 H7/g6 as a "precision sliding fit," you have unlocked a level of design communication that transcends language and national borders.
Official and informative documents regarding ISO 286 can be found through various technical repositories: ISO 286-2 - iTeh Standards
The standard is divided into two primary parts to serve both theoretical and practical needs: | IT Grade(s) | Precision Level | Typical
What are the of the parts you are designing?
ISO standards are protected by international copyright laws. Unauthorized distribution or downloading of ISO 286 PDFs from illegal websites is prohibited. Always purchase standards from authorized sources to ensure you have the latest, correct version and to support the development of future standards.
If you are currently setting up a specific engineering drawing, please let me know: What you are working with? Once you can read Ø25 H7/g6 as a
In this approach, the hole size is kept constant (usually using the designation, where the lower limit equals the nominal size), and the shaft tolerance is varied to achieve the desired fit.
: In a hole-basis system , the lower deviation of the hole is zero (denoted as 'H'). In a shaft-basis system , the upper deviation of the shaft is zero (denoted as 'h').
ISO 286 is not just a set of tables — it is a logical, internationally agreed language for controlling size variation in manufacturing. The official PDF is an essential reference for any engineer, machinist, or quality professional. While the full document is protected by copyright and must be purchased, its concepts are widely summarized in textbooks and training materials. Understanding ISO 286 is a fundamental step toward producing parts that assemble correctly, function reliably, and fit within global supply chains.
Components manufactured by entirely different suppliers will fit together seamlessly upon final assembly.
standard is the internationally recognized system for limits, fits, and tolerances