Simply put: It tells the machinist how to treat the "leftover" edges—those small intersections between two surfaces where no specific radius or chamfer is called out.
is a critical international standard for mechanical engineering that defines how to specify the state of edges with "undefined shapes" in technical product documentation. While CAD models represent parts with perfect geometric edges, real-world manufacturing processes like milling, casting, or stamping inevitably leave burrs (excess material) or undercuts (removed material).
To make the symbol useful, data is added to it. The convention for adding values is strictly defined:
This standard provides a universal symbolic language to communicate exactly how much material can be added or removed from an edge to ensure safety, functionality, and proper assembly. Core Purpose and Scope din iso 13715
Over-specifying is expensive. If you demand a minimum radius of 0.2 mm on every edge, a machinist might have to hand-deburr with a file. A specification of allows them to use a vibratory tumbler or belt sander, saving hours of labor.
"All undefined edges: Max R 0.4 according to DIN ISO 13715." Now it is objective, measurable, and inspectable.
While you can dimension a chamfer explicitly (e.g., "0.5 x 45°"), DIN ISO 13715 offers several advantages: Simply put: It tells the machinist how to
If you have ever looked at a technical drawing and seen a small "x" or a checkmark near a corner and wondered what it meant, you have encountered .
"Create a chamfer or round with a maximum dimension of 0.5 mm." Note: The standard typically treats the value as a maximum limit. If the drawing specifies 0.5 - , the actual chamfer can be anywhere from 0 to 0.5 mm.
The primary goal of DIN ISO 13715 is to bridge the gap between ideal geometry and physical reality. It applies when the exact shape of an edge is not critical enough to require a specific dimension (like a 1x45° chamfer), but its "state" (sharp, burred, or undercut) must still be controlled for the part to work. To make the symbol useful, data is added to it
Enter . This standard is the universal language for defining the condition of undefined edges on technical drawings.
DIN ISO 13715 is one of those standards that does the heavy lifting of communication without cluttering the drawing with unnecessary text. By mastering the use of the edge symbol and understanding the difference between a burr, a sharp edge, and a chamfer, you ensure that your designs are manufactured safely, functionally, and exactly as intended.