CHOOSING A FIT SYSTEM
Choosing a Tolerance System
How to choose a hole-basis or shaft-basis fit using the available standard component and the required assembly function.
Tolerance selection
The choice between a hole-basis and shaft-basis system depends on the standard parts available and the intended assembly. A component with a specified bore tolerance may lead to a hole-basis design; a shaft supplied to a standard tolerance may lead to a shaft-basis design.
Fit pairs and application
Clearance, transition and interference fits are selected for function, motion, load and assembly method. Common ISO designations such as H7/h6 or H7/k6 are examples, not universal rules. Confirm the actual limits for the nominal size using the applicable ISO 286 tables and project requirements.
Review the detailed Fits and Tolerances guide for fit types, limits and examples.