ISO 286 Shaft Tolerances and Fits
Reference chart of shaft and hole tolerances with clearance, transition, and interference fits according to ISO 286
ISO 286 Tolerances and Fits Table
| Fit Type | Example Designation | Typical Application |
|---|---|---|
| Clearance Fit | H7/g6, H8/f7 | Rotating shafts, sliding assemblies where free movement is required |
| Transition Fit | H7/k6, H7/n6 | Locating fits, where shafts may require light press or free running depending on tolerance |
| Interference Fit | H7/p6, H7/s6, H7/u6 | Permanently fixed joints such as gears, bearings, or bushings on shafts |
About ISO 286 Shaft Tolerances and Fits
ISO 286 defines the internationally recognized standard system for shaft and hole tolerances, providing a consistent method to specify clearance, transition, and interference fits for engineering assemblies. This standard ensures reliable mechanical performance by controlling the permissible deviations in shaft and hole diameters across nominal size ranges.
Using the correct ISO 286 fit designation (e.g., H7/g6 or H7/p6) ensures proper assembly behavior. Each designation combines a tolerance position (letter) and tolerance grade (IT number) to define the allowable dimensional variation. Lower IT grades correspond to tighter tolerances for precision applications.
Fit Type Definitions
- Clearance Fit – The shaft is always smaller than the hole, allowing free movement, suitable for rotating or sliding parts.
- Transition Fit – The shaft and hole may assemble with either slight clearance or light interference, ideal for precise location or alignment applications.
- Interference Fit – The shaft is slightly larger than the hole, producing a tight press fit for permanent connections like bearings, gears, or bushings.
- Tolerance Grade (IT) – Defines the allowable deviation for a nominal dimension. Smaller IT grades indicate higher precision.
Engineering & Manufacturing Applications
Engineers, designers, and machinists use ISO 286 shaft tolerances and fits to:
- Specify correct fit types and tolerances for shafts and holes based on nominal diameters.
- Ensure predictable assembly behavior and consistent mechanical performance.
- Maintain interchangeability across production facilities and suppliers worldwide.
- Reduce machining errors, rework, and variation in manufacturing while improving component reliability.
ISO 286 shaft and hole tolerances are essential for industries ranging from automotive and aerospace to industrial machinery and robotics. Adhering to these standards allows precise control of fit, proper torque transmission, smooth operation of assemblies, and long-term durability of mechanical components.