Technical product documentation - Edges of undefined shape - Indication and dimensioning
1Key Takeaways
This document specifies rules for the indication and dimensioning of undefined edges in technical product and dimensions. The proportions and dimensions of the graphical symbols to be used are also specified. In cases where the geometrically defined shape of an edge (for example, 1 × 45°) is required, the general dimen…
2Expert Interpretation
An in-depth analysis of the international standard ISO 13715:2017, "Technical product documentation — Dimensioning and marking of edges of undefined shapes," covering edge type symbology, dimensioning rules, direction indication methods, and implementation cases. It is applicable to the standardized processing of mechanical engineering drawings.
Analysis of the core content of the standard
As an important standard in the field of technical product documentation, ISO 13715:2017 systematically standardizes the annotation method for the edges of undefined shapes. The standard mainly includes the following technical elements:
| Technical Elements | 2000 Edition | Main Changes in 2017 Edition |
|---|---|---|
| Standard Name | Technical Drawing - Undefined Shape Edges | Technical Product Documentation - Undefined Shape Edges |
| Symbol System | Basic Annotation Symbols | New Asymmetric Annotation (4.4.2) |
| Appendix Structure | Includes Recommended Edge Sizes | Delete this appendix and add Example Appendix B |
Key Technical Requirements
1. Edge Type Symbol System
The standard defines three basic symbol elements:
- +: Indicates that excess material is allowed (i.e., transition)
- -: Indicates that material removal is required (i.e., undercut)
- ±: Indicates that excess material or removal is allowed (requires dimensioning)
2. Dimensioning Specifications
Edge deviation is controlled through four typical dimensioning methods:
- Single positive limit: Indicates an allowed transition from 0 to the calibrated value
- Single negative limit: Indicates a mandatory undercut from 0 to the calibrated value
- Dual limit annotation: The upper limit is marked above the lower limit
- Asymmetric annotation: Different limits are marked in different directions
Application case: Edge processing of hydraulic valve blocks
The hydraulic valve blocks produced by a CNC machining center need to be marked:
External edge: ±0.1 (transition/undercut allowed) Internal oil channel edge: -0.2 (forced undercut)
This marking ensures the flatness of the assembly surface and prevents burrs in the oil channel from affecting fluid performance.
Implementation Suggestions
1. Drawing Annotation Process
- Identify Functionally Critical Edges
- Determine Edge Treatment Type (Transition/Undercut)
- Determine Tolerance Range Based on Process Capabilities
- Use Standard Symbols for Standardized Annotation
2. Common Problem Solving
| Problem Type | Standard Solution |
|---|---|
| Non-90° Edge Annotation | Only Dimension Without Specifying Direction (4.4) |
| Special Requirements for Local Edges | Use Dashed Lines to Define Areas (4.5.3) |
| Multiple exception annotations | Use brackets for additional explanations (4.5.5) |
Standard Evolution Analysis
Compared with the 2000 version, the 2017 version has the following major technical improvements:
- Expansion of the scope of application: Upgrade from "technical drawing" to "technical product documentation"
- Improvement of the annotation system: Addition of asymmetric annotation requirements
- Systematization of examples: Integration of the original scattered examples into a normative appendix
This standard, together with the ISO 129-1 dimensioning standard and the ISO 1101 geometric tolerance standard, constitute the core components of the mechanical drawing standard system.