The second letter defines boundaries for physical shape variations, specifically straightness, flatness, and structural parallelism. These metrics use an alternative rating scale: : Fine F : Medium G : Coarse H : Very Coarse.
This article provides an in-depth look at , explaining its scope, classes, and importance in modern engineering. What is EN ISO 13920?
Ensuring parts are correctly positioned relative to each other. Application and Usage en iso 13920-bf
The widespread adoption of EN ISO 13920 is driven by its significant practical benefits:
This class specifically governs the geometric tolerances of the weldment, including how straight a part is or how flat a surface must be. 2. Tolerance Tables for Class B (Linear & Angular) The second letter defines boundaries for physical shape
Class F regulates straightness, flatness, and parallelism, with tolerances increasing based on the component's size. For example, for sizes over 30mm up to 120mm, the max deviation is 1mm, scaling up to 16mm for sizes over 20,000mm. Why EN ISO 13920-BF Dominates Manufacturing
: Accuracy of angles between welded parts. What is EN ISO 13920
The two letters in the designation refer to separate tables within the ISO standard. Each letter represents a specific degree of accuracy, ranging from fine to coarse.
Angular deviations are calculated based on the length of the shorter leg of the angle: ±45′plus or minus 45 prime ±13plus or minus 13 400 mm to 1,000 mm: ±30′plus or minus 30 prime ±9plus or minus 9 Over 1,000 mm: ±20′plus or minus 20 prime ±6plus or minus 6 3. Geometrical Tolerances (Class F)
It prevents over-engineering (specifying tighter tolerances than necessary), saving time and reducing production costs.