What is an acute punch?
An acute punch has an included angle smaller than 90 degrees, typically 30, 35, 45 or 60 degrees. It lets the punch enter a narrow die opening and produce an acute bend angle in air bending, where a 90 degree punch would collide with the die shoulders.
What angles are acute punches supplied in?
Common included angles are 30 and 35 degrees for the most acute work, 45 and 60 degrees for intermediate angles, and 88 degrees as the general-purpose profile that produces 90 degree bends in air bending.
| Punch included angle | Typical bend angle achieved | Notes |
|---|---|---|
| 30° | Down to about 30° | Highest tip load, narrowest die needed |
| 35° | Around 35–45° | Common acute profile |
| 45° | Around 45–60° | Balanced between reach and load |
| 60° | Around 60–80° | Moderate acute work |
| 88° | 90° with springback allowance | General-purpose air bending |
Why does an acute punch need more force?
The tip is narrower, so the same bending force is carried by a much smaller contact area. The load per millimetre at the tip rises sharply, which is why acute punches usually carry a lower rated load than a general-purpose profile.
What die opening should be used with an acute punch?
A narrower die opening than the eight times rule would suggest, because the acute angle has to be formed before the punch reaches the die shoulders. Narrowing the die raises the tonnage, so both the machine and the tool rating have to be re-checked.
| Effect | Direction | Consequence |
|---|---|---|
| Die opening | Narrower | Radius tightens, flange minimum grows |
| Tonnage | Higher | Must stay inside machine and tool ratings |
| Marking risk | Higher | Consider urethane or anti-mark tooling |
| Punch reach | Better | Acute angle can be formed without collision |
When is an acute punch the wrong choice?
When the required angle can be reached with a standard punch and a bend sequence that avoids collision, or when the material cannot tolerate the tighter radius the narrow die produces.
- If a 90 degree punch plus a wider die can reach the angle, use it: the load is lower.
- If the material's minimum bend radius is the real limit, sharpen the die and the tooling will not help.
- If the part is short-run, a standard punch and a reduced-shoulder die may be cheaper.
- For deep box sections, a gooseneck profile solves reach better than an acute angle.
Related technical pages
Gooseneck punches
Reach over an upstand rather than a narrow angle.
Tooling load calculator
Check the tip load before running an acute tool.
Minimum bend radius
Whether the tight radius the narrow die produces is safe.
Press brake punches
All punch profiles and when to use each.
Next step
Send the part drawing and the bend angle and we will confirm whether a standard or acute profile can form it, and at what load.
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