A key element of the ISO 8015 chart is the set of modifiers that override the Independency Principle:
| Feature | ISO 8015 (International) | ASME Y14.5 (USA) | | :--- | :--- | :--- | | | Independence. Size is size; Form is form. They are unrelated unless specified. | Envelope (Taylor Principle). Size limits generally control form (Rule #1). | | Tolerance Chart Usage | Used to define local size limits only. | Used to define size limits and form boundaries. | | Flexibility | Offers high flexibility. A manufacturer can produce a part with poor form if the drawing does not specify form tolerances. | Offers stricter default quality. Form is automatically controlled. | | Ambiguity | Low. Explicitly states that drawings do not imply manufacturing methods. | Low, but relies heavily on the "Rule #1" concept. | iso 8015 tolerance chart
: Every dimensional or geometric tolerance must be met on its own. For example, a diameter tolerance only controls the local size (two-point measurement) and does not limit how much the part can deviate from a perfect cylinder. A key element of the ISO 8015 chart
It addresses the core problem: