Zero-Value Tolerance Not Allowed(ISO)
In general, a zero-value
tolerance represents an unmanufacturable condition and is not allowed.
Geometrical Tolerances
In general, the tolerance value specified for a
geometrical tolerance should be greater than zero. An exception where a zero-value tolerance is acceptable is a geometrical tolerance (e.g., position) which has a Ⓜ or Ⓛ tolerance zone
material requirement applied. In that case, the two requirements of size and geometrical tolerance are transformed into a single
collective requirement.
To eliminate this problem, you should either change the tolerance to a non-zero value or in the case of a zero-value geometrical tolerance, specify a Ⓜ or Ⓛ tolerance zone material requirement.
Dimensions
All dimensions (except for auxiliary dimensions) must have a tolerance specified in one of the following ways:
• A non-zero tolerance value is specified explicitly for the dimension (e.g., 12.6±0.1).
• The tolerance is specified by reference to a tolerance table (e.g., 12.6 A9).
• The dimension is shown without a tolerance indication but ISO 2768 is referenced with a tolerance class indication of f, m, c, or v (e.g., ISO 2768-mK) for general linear and angular dimensions.