The engineering code specifies the standard for general tolerances applied to welded constructions. It combines Class B (representing a "medium" precision category for linear and angular dimensions) with Class F (specifying the "medium" precision limits for shape, position, flatness, and parallelism).
However, in practice, when designers write , they usually mean:
The suffix brings together two independent metrics from the standard: en iso 13920-bf
: If a critical feature requires tighter control than what Class BF provides, that specific dimension must be toleranced individually on the drawing. The individual tolerance always overrides the general standard.
This is the tolerance class for lengths (like the distance between two plates) and angles. Class The engineering code specifies the standard for general
: It provides a clear benchmark for what is considered an acceptable "standard" build in industrial fabrication.
for Class B and F. Compare Class BF with other classes like CE or AE. Discuss how this standard impacts the cost of fabrication. for Class B and F
Ensuring manufactured parts meet design requirements.
: The standard must be explicitly referenced in or near the drawing title block. It is typically written as: EN ISO 13920-BF (or ISO 13920-BF).