En Iso 13920-bf !!top!! < 2026 >
The code "BF" consists of two distinct tolerance classes defined in ISO 13920 :
| Nominal Dimension Range (mm) | Tolerance (± mm) | | :--- | :--- | | >30 to 120 | 1.0 | | >120 to 400 | 1.5 | | >400 to 1000 | 3.0 | | >1000 to 2000 | 4.5 | | >2000 to 4000 | 6.0 | | >4000 to 8000 | 8.0 | | >8000 to 12000 | 8.0 |
Refers to the tolerance class for angular dimensions. These are usually classified as E (Fine), F (Medium), or G (Coarse). Class F indicates "medium" tolerances for angles.
Q: Can EN ISO 13920-BF be used for non-welded constructions? A: No, the standard is specifically designed for welded constructions and parts. Other standards may apply to non-welded constructions. en iso 13920-bf
| Nominal Dimension Range (mm) | Limit Deviation (± mm) | | :--- | :--- | | 2 to 30 | ± 2 | | >30 to 120 | ± 2 | | >120 to 400 | ± 3 | | >400 to 1,000 | ± 4 | | >1,000 to 2,000 | ± 6 | | >2,000 to 4,000 | ± 8 | | >4,000 to 8,000 | ± 10 | | >8,000 to 12,000 | ± 12 | | >12,000 to 16,000 | ± 14 | | >16,000 to 20,000 | ± 16 |
Conveyor supports, crane bridges, and racking systems. Implementing BF Tolerances in Production
Scales based on length (e.g., 0–30mm, 30–120mm, up to 20,000mm). The code "BF" consists of two distinct tolerance
The selection of a tolerance class has a direct impact on manufacturing cost, complexity, and risk. The "BF" combination is widely used because it represents a practical balance between precision and economic reality.
The classes are independent of each other, meaning a drawing can call for a high-precision size (e.g., class B) while still allowing for a wider tolerance on shape (e.g., class F). This is exactly what the combination signifies: class B for dimensions (lengths & angles) and class F for geometry (shape & position) . The specification ISO 2768-mk is used for a similar purpose but for machined parts, while ISO 13920-BF is used explicitly for welded constructions .
The standard was originally published in 1996. A significant update was released in , which supersedes the 1996 version. If you are referencing older documentation, be aware that EN ISO 13920-BF as a code has remained in use, but any new designs should refer to the 2023 edition of the standard to ensure compliance with the latest requirements. Q: Can EN ISO 13920-BF be used for non-welded constructions
It is not intended for critical mating features, which require individually specified tolerances (e.g., ISO 286 for hole-shaft fits), nor for dimensions that are crucial to a part's core function.
Designing foundations for pumps or blowers. Transport: Fabricating chassis or frames for vehicles.
Source: DIN EN ISO 13920 Standard.
