Din 76-a Pdf
A sharp 90-degree corner between a thread and a shoulder creates a massive stress concentration point, leading to fatigue failure. DIN 76-A introduces a controlled radius ( ) that distributes stress evenly.
Ensure that the internal thread of the mating part has a proper countersink/chamfer. This works in tandem with the DIN 76-A undercut to guarantee a flush fit. Account for Tool Wear: The radius (
The DIN 76 standard ensures that every machinist and designer works from the same set of dimensions, so that a thread made in Berlin will fit a mating part made in Shanghai. As one German reference puts it: “The thread run‑out or thread undercut must be manufactured in order to be able to cut a thread perfectly down to a shoulder.” din 76-a pdf
| Thread pitch ( P ) (mm) | Undercut length ( g_2 ) (approx.) | Undercut diameter | Transition radius ( R ) | Relief angle | |--------------------------|--------------------------------------|--------------------|--------------------------|--------------| | 0,2 | 0,7 mm | 0,3 mm | 0,1 | 30° | | 0,25 | 0,9 mm | 0,4 mm | 0,12 | 30° | | 0,3 | 1,05 mm | 0,5 mm | 0,16 | 30° | | 0,35 | 1,2 mm | 0,6 mm | 0,16 | 30° | | 0,4 | 1,4 mm | 0,7 mm | 0,2 | 30° | | 0,5 | 1,75 mm | 0,8 mm | 0,2 | 30° | | 0,6 | 2,1 mm | 1,0 mm | 0,4 | 30° | | 0,7 | 2,45 mm | 1,1 mm | 0,4 | 30° | | 0,75 | 2,6 mm | 1,2 mm | 0,4 | 30° | | 0,8 | 2,8 mm | 1,3 mm | 0,4 | 30° | | 1,0 | 3,5 mm | 1,6 mm | 0,6 | 30° | | 1,25 | 4,4 mm | 2,0 mm | 0,6 | 30° | | 1,5 | 5,2 mm | 2,3 mm | 0,8 | 30° | | 1,75 | 6,1 mm | 2,6 mm | 1,0 | 30° | | 2,0 | 7,0 mm | 3,0 mm | 1,0 | 30° | | 2,5 | 8,7 mm | 3,6 mm | 1,2 | 30° | | 3,0 | 10,5 mm | 4,4 mm | 1,6 | 30° | | 3,5 | 12,0 mm | 5,0 mm | 1,6 | 30° | | 4,0 | 14,0 mm | 5,7 mm | 2,0 | 30° | | 5,0 | 17,5 mm | 7,0 mm | 2,5 | 30° | | 6,0 | 21,0 mm | 8,3 mm | 3,2 | 30° |
What (e.g., M10, M20) are you working with? Are you designing for high-fatigue load applications? Do you need the measurements in metric or inch conversions ? Share public link A sharp 90-degree corner between a thread and
Among these three, is by far the most frequently used, and it is the one that contains Form A (DIN 76‑A) and Form B for external threads, as well as Form C and Form D for internal threads. The current version of DIN 76‑1 was published in August 2016 (DIN 76‑1:2016‑08) and supersedes all earlier editions going back to 1924.
The undercut must always be machined before the threading operation begins. This gives the threading insert a clear space to drop into or exit from during the threading passes. This works in tandem with the DIN 76-A
The most significant feature of DIN 76-1 is that it defines two distinct types of thread undercuts :