What is press brake tooling?
Press brake tooling is the matched punch and die set that forms sheet metal on a press brake. The punch presses the sheet into the die opening to create a bend. Tooling determines the achievable angle, inner radius, minimum flange length and the bending tonnage required.
What are the main punch profiles?
The main punch profiles are standard or straight, gooseneck, acute, sash or offset, hemming and flattening, and radius punches. Each profile exists to solve a specific clearance, angle or surface problem rather than to bend a different material.
Standard or straight punch
The general-purpose profile for 90 degree bends. It is the strongest of the common profiles because it has the shortest unsupported overhang, but it needs clearance above the die for return flanges.
Gooseneck punch
A deep profile that clears the upstand of a return flange. It allows box and pan work that a straight punch cannot reach, at the cost of some stiffness.
Acute punch
An included angle of roughly 28 to 60 degrees, used to over-bend so that springback returns the part to the required angle.
Sash or offset punch
A thin, straight profile with a relief offset, used for narrow bends on frames and profiles where a standard punch would foul.
Hemming and flattening
Closes a folded edge flat, either as a two-step operation or with a dedicated tool.
Radius punch
Produces a controlled inner radius without needing a wide die opening, which is useful when the die opening is fixed by the machine or the part.
What are the main die types?
The main die types are single-V, 2V, multi-V, T-style and rotary or Rolla-V dies. The choice is driven by how many different thicknesses you bend, how often you change over, and whether surface marking is acceptable.
| Type | Openings | Best for | Trade-off |
|---|---|---|---|
| Single-V | 1 | One thickness, one radius, simplest setup | Changeover requires a different die |
| 2V | 2 | Two common thicknesses without set screws | Limited range, larger body |
| Multi-V | up to 4 | High-mix work across a thickness range | Larger, heavier body, less clearance |
| T-style | 1 or 2, 80 or 120 mm body | Narrow bed machines, low profile | Lower tonnage capability |
| Rolla-V (rotary) | 1, rotating insert | Mark-free bending on coated or polished sheet | Higher cost, dedicated use |
Which shank and tang standards exist?
There are three interfaces in general use: the 13 mm tang of the Amada and Promecam-derived European system, the 20 mm safety tang with locking pins used by Trumpf and Wila, and the 1/2 in shank of the American system. They are not interchangeable without adapters.
| System | Interface | Retention | Common machines |
|---|---|---|---|
| Amada style | 13 mm tang | Clamp only, no safety pin | Amada and Amada-interface machines |
| Trumpf / Wila style | 20 mm safety tang | Locking pins in the clamp | Trumpf, Wila, Bystronic |
| American style | 1/2 in (12.7 mm) shank | Separate punch holder and set screws | Accurpress, Cincinnati, Pacific, Wysong |
| European style | 13 mm tang, or 20 mm on newer machines | Depends on the clamp generation | LVD, SafanDarley, Adira |
How do I select the die opening, radius and minimum flange?
Select the die opening first, because it sets the inner radius, the minimum flange and the tonnage. For mild steel start at V = 8t, then check the resulting radius against the drawing and adjust the opening before considering any other change.
- Die opening: V = 8t for mild steel as a starting point; V = 6t for a tighter radius; V = 12t to reduce tonnage.
- Inner radius: approximately 0.16 × V in air bending.
- Minimum flange: approximately V/2 + t, because the flange must rest on the die shoulders.
- Tonnage: F = 1.42 · σb · L · t² / (1000 · V), in kilonewtons.
What tool steel and hardness should be specified?
42CrMo4 (DIN 1.7225) and 1.2379 (AISI D2 equivalent) are the two steels most used for press brake punches and dies. Hardness is supplied from 45 to 60 HRC as per item or request.
Higher hardness resists abrasive wear but reduces toughness, so narrow tips and acute profiles can be more prone to chipping at the top of the hardness range. Specify hardness against the actual work: heavy plate and abrasive material favour higher hardness, while thin, intricate profiles favour toughness.
What are the common failure modes and how is tooling maintained?
The common failure modes are tip wear, chipping of narrow profiles, galling or pick-up on the punch face, and loss of accuracy after repeated regrinding. Tooling is maintained by regrinding the punch tip or the die faces and by checking for cracks before returning the tool to service.
- Tip wear widens the effective radius and changes the bend angle.
- Chipping usually follows overloading a narrow punch or using a tool beyond its rated tonnage.
- Galling transfers material to the tool face; polishing and lubrication reduce it.
- Regrinding removes wear but reduces height, so tools must be re-matched across the set.
Frequently asked questions
The answers below cover the questions buyers ask most often about tooling selection and bending physics.
- What is the difference between a press brake punch and a die?
- The punch is the upper tool that pushes the sheet down; the die is the lower tool with the V opening that the sheet bends into. Together they set the bend angle, the inner radius, the minimum flange length and the tonnage needed.
- How do I choose the V opening for a press brake die?
- Start with V = 8t for mild steel, where t is the sheet thickness. A smaller opening such as V = 6t gives a tighter inner radius but needs more tonnage; a larger opening such as V = 12t reduces tonnage but increases the radius and the minimum flange length.
- What inner radius does air bending produce?
- In air bending the inner radius is roughly 0.16 times the die opening, so a 16 mm V opening gives an inner radius near 2.5 mm. If a specific radius is required, either change the die opening or use a radius punch.
- How is minimum flange length determined?
- As a rule of thumb the minimum flange is about half the die opening plus the material thickness. The flange must be long enough to rest on the die shoulders. A narrower punch tip or a die with reduced shoulder width allows shorter flanges.
- What causes springback and how is it controlled?
- Springback is the elastic recovery of the sheet after the punch is withdrawn. It is controlled by over-bending, which is why 88 degree punches are used for 90 degree bends, and by choosing a die opening and radius that suit the material.
- What is crowning and when is it needed?
- Crowning compensates for the deflection of the ram and bed under load, which otherwise makes the bend angle shallower in the middle of the part than at the ends. It is needed when bending long parts where angle consistency along the length matters.
- What is the maximum tonnage a press brake tool should be loaded to?
- Calculated bending force should stay comfortably below the rated capacity of both the machine and the tooling. A common practice is to size the operation so it stays under roughly 80 per cent of the rated tonnage, and to check the tool maker's own load limit for narrow punches.
- How long does press brake tooling last?
- Service life depends on material, thickness, cycle count and whether the tool is reground. Tooling is normally reconditioned by regrinding the punch tip or the die faces; once the profile no longer meets the drawing, the tool is replaced.