Stahlschmidt & Flender GmbH
Aherhammer 3-9
D-57223 Kreuztal
Tel. +49 (0) 27 32 / 58 53 - 0
Fax +49 (0) 27 32 / 2 75 44
E-Mail: info@aherhammer.de
Technical Standards
8. Breakaway on holes (Conical section of hole)
If the punch has penetrated deeply enough into the material, the material will begin to tear mainly from the cutting side of the matrix .
| t | = thickness of the sheet |
| w | = diameter of the hole |
| w1 | = maximum breakaway diameter |
| h | = height of the breakaway zone |
| r | = turn in radius |
| y | = deformation zone |
| c | = cutting zone (cylindrical) |
The conical section of the hole depends on:
a) shear strength of material
b) metallurgical analysis of material
c) die clearance of the punching tool
In summary:
There cannot be fixed tolerances for the shape and dimensions of the breakaway zone.
It can be estimated the breakaway zone 'h' will be between 0,6 x t and 0, depending on the above mentioned components.