Iso 8015 Tolerance -

It removes "hidden" rules about form that might vary between different countries' national standards.

While ISO 286 governs fits and ISO 1101 governs geometrical tolerancing symbols, ISO 8015 answers a more philosophical question: How do these different types of tolerances interact?

ISO 8015 replaces this implicit control with explicit control. Its central tenet, the , states that each specified dimensional or geometrical requirement is independent of any other unless a specific relationship is indicated (e.g., by the use of modifiers like Ⓜ for maximum material condition). In practice, this means that a size tolerance controls only local two-point sizes; it does not control straightness, flatness, roundness, or cylindricity. Those form deviations must be controlled by their own separate geometrical tolerances. iso 8015 tolerance

The ISO rationale is that modern manufacturing and metrology are increasingly decoupled.

By strictly defining tolerances, parts manufactured in different parts of the world are more likely to fit together correctly during assembly. It removes "hidden" rules about form that might

The rules of engagement are clear. A turned shaft with a size tolerance of ±0.1 mm can be produced on a simple lathe; slight bowing is permitted as long as the local diameters are correct. If the assembly requires a straight shaft, the drawing must include a straightness tolerance, signaling the need for centerless grinding or straightening. ISO 8015 eliminates the guesswork and potential for costly rework based on unstated assumptions.

It does control the form (e.g., straightness, circularity, or cylindricity) of the feature. Its central tenet, the , states that each

The defining feature of ISO 8015 is the . According to this rule:

ISO 8015 is more than just a technical document; it represents a philosophy of precision that prioritizes explicit intent over implied rules. By establishing the , it acknowledges the reality of modern manufacturing—where size and shape are distinct entities requiring distinct controls.

Before this standard became the global norm, many regional standards assumed a link between size and form (for example, if a hole's diameter was within tolerance, its roundness was assumed to be somewhat controlled by that same limit). Under ISO 8015: