Approach a press brake tooling rack and you’ll find there are a dozen, if not more, tools that look virtually identical.
They are not.
The bend radius, force required, clearance available and even whether the next bend is physically possible can vary with a slight variation in punch nose, a slight variation in V-opening and/or a slight variation in tool profile.
That’s why it is best to start by looking at the part itself and not a tooling catalog in a press brake tooling explained session.
APEX is used for the tooling and accessories of press brake machines, which are grouped around upper punches, lower dies, holders, adapters, segmented tooling, clamps and other supporting systems. The important question is how do those components convert the drawing into a repeatable bend?
How the Punch and Die Do Different Jobs
The top tool is the punch. The die is used to support the sheet from below.
Simple to say, but the impact they have on the part is different.
In the air bending application the sheet does not usually impact the bottom of the V-die, but instead the punch tip and two shoulders of the V-die. The punch penetration determines the angle and the die opening is a significant factor to the naturally formed inside radius.
This, of course, provides operators with a new way of considering tooling:
Punch: Is it possible to generate the necessary profile without collision with the part?
Die: Will it provide the necessary sheet support with an acceptable radius and flange and forming load?
To not check one without the other is half the set up.
Choose the V-Die From More Than Sheet Thickness
The approximate starting point for mild-steel air bending is about an opening of 8 times the material’s thickness.
It’s a starting point, not to end thinking.
According to the APEX’s V-die opening guide, that’s why. A change in the opening impacts required tonnage, minimum flange support, surface marking and material movement, inside radius. Smaller openings tend to promote tighter bends and shorter flanges, yet need more force, while larger openings have less force available and tend to result in a larger natural radius and need greater flange support.
Prior to choosing the die, check:
material and thickness in reality; Thickness
required inside radius;
shortest flange;
bend length;
surface-finish requirement;
available capacity of the machine and tooling.
A die may make the proper angle and still be incorrect for the part.
Often a clearance decision is a punch shape decision.
Sometimes operators choose a punch according to only the tip angle.
That’s quickly proved to be inadequate when it comes to complex components.
Suppose that the box is bent. Once the first two sides are done, the resulting flanges must go around the upper tool during the next bend. A straight punch that is effective at the first bend could hit the part at a later stage in the sequence.
This is where narrow segmented or “gooseneck” type tooling can be of value. APEX explicitly points to segmented and geometry-specific tools that are used for boxes, return bends, small flanges and using existing geometry as an obstruction.
Thus, before selecting the punch, try the whole bend sequence in your head (or on your computer).
The crucial question is:
Is there a way to get Bend 1 using this tool?
It is:
Does this part still fit around this tool at Bend 4?
| Part Requirement | Tooling Question | Likely Direction |
| Standard open bend | Is there enough part clearance? | Straight punch + suitable V-die |
| Deep box | Will the formed flange hit the punch? | Relieved / gooseneck punch |
| Short component | Is full-length tooling necessary? | Segmented tooling |
| Short flange | Can the die support the edge? | Review smaller V-opening |
| Large inside radius | Can the natural radius meet the drawing? | Wider V / radius tooling |
| Sensitive surface | Will die shoulders leave marks? | Review contact radius / protection |
| Return bend | Will previous bends interfere? | Clearance-specific tooling |
Air Bending, Bottom Bending and Coining Do Not Use Tooling Equally
Many different forming conditions can be grouped under the same punch and die terminology.
In air bending a small amount of contact is used between the sheet and tooling, and typically the least amount of force is used of the three methods. Also offers high angle flexibility with punch penetration.
The greater the bottom bending, the more sheet will conform to the tooling, and the angles of punches and dies must be more closely matched.
Coining is a much more severe process, with much higher pressure and much closer fit towards the tool geometry. Thus it involves higher loadings on the machine and tooling.
That disparity is significant prior to an order for a tooling.
It is not always a question of looking like a profile, but if a tool is chosen for flexible air bending at some stage it should be understood that it is not necessarily suitable for a high load forming operation.
Don’t Separate V-Die Selection From Tonnage
The fact that the experienced operators are not enthusiastic to install a smaller die is due to the practical reasons.
Force goes up.
In APEX’s press brake tonnage calculation guide, you can enter the material strength, actual thickness, and bend length as well as the V-opening and punch radius to calculate the bending force. It also cautions that machine rated tonnages do not necessarily imply that full force can be applied to all of the short tool sections or off-center bends.
It requires there to be three load limits that need attention:
machine capacity;
punch capacity;
die capacity.
When segmented tooling is being used for a short bending length, see the load allowable for that length of tool, and not the machine’s rating.
Not all tooling is geometry.
It is also a system of load bearing.
Segmented Tooling Solves Jobs Where Full-Length Tooling is Awkward
A three meter tool doesn’t have to be a three meter tool for each job.
Shorter punches and dies can be used to create the desired working length with segmented punches and dies. This can be helpful when making boxes, etc. and when there are narrow sections and bends where finished sidewalls might get trapped around the continuous tooling.
Segmentation also provides greater flexibility in the arrangement of the tools, with the additional demand of alignment.
The machine bed, holders and tool sections must have clean contact surfaces, and should act as though they were all part of one continuous bending line.
APEX’s press brake setup guide advises cleaning the machine and tooling surfaces, checking the tools and setting up the press brake prior to first part validation.
Even an advanced system on debris is a bad set-up.
Typically, Tool Wear is first observed on the part before it is noticeable on the tool.
Before tooling can negatively impact production, it doesn’t always have to be visibly broken.
If worn on a punch tip or V-die shoulder, the contact conditions on the bend will be changed. Marking or inconsistent results can also be caused by chips, dents and localized wear.
Always check the working surfaces in advance of installation, and don’t assume that if one part of an older tool matches, the entire tool is the same size.
According to APEx’s tooling guidance tips are to be checked for cracks, chips, dents and wear, and the straightness and alignment of die shoulders should be checked.
The completed piece offers a further hint. If the angle or straightness varies regularly at the same spot down the tooling, check the tool or the CNC program, but do not keep tuning the CNC program.
The press brake bending accuracy guide also lists “tooling wear” as one of the variables that should be controlled when checking the repeatability and bend-line accuracy.
| Inspection Point | What to Look For | Why It Matters |
| Punch Tip | Wear, chip, dent | Changes local bend contact |
| Die Shoulder | Wear or damage | Can affect marking and consistency |
| Tool Body | Crack or deformation | Load and safety concern |
| Tool Surface | Dirt, scale, oil residue | Prevents stable seating |
| Segments | Height / alignment difference | Creates uneven bending line |
| Holder Contact | Debris or poor clamping | Affects tool position |
| Tool ID / Load Rating | Correct tool and capacity | Prevents setup and overload errors |
Establish a Tool Library of Real Part(s)
Not all profiles in a catalog are essential for a good tooling library.
It requires a set of tools that encompass the factory’s geometry, which is repeated across the site.
Inspect a representative sample of drawings and document materials, thickness, inside radius, flange size, bend angles and challenging interference situations. Next determine which tooling combinations are able to accommodate the most useful part families.
The specific recurring production limitation should be solved by providing special tooling.
As much routine tooling as can be should be performed using standard tooling.
That way you have a more productive set of tools than purchasing tools “just in case.
The good selection of press brake tooling is a working backwards process:
finished part → bend method → geometry → punch and die → load check → setup → test bend.
After this sequence is second nature, the tooling rack is a lot easier to understand.
FAQ
Q1. What do you need in press brake tooling?
The most important components are the upper die and lower die. The tooling system is completed with holders, adapters, segmented sections and clamping systems and supporting accessories.
Q2. How to select the V-die opening?
First consider the type and thickness of material, followed by the desired inside radius, minimum flange, surface finish and forming force. The 8× thickness rule is just a rule of thumb for conventional air bending.
Q3. What does gooseneck punch do?
It has a raised profile which allows more clearance for existing formed flanges. This can be helpful for boxes, channels and return-bend parts that could be subject to interference during a straight punch.
Q4. Is it always true that a smaller V-die results in a better bend?
No. A smaller opening may be able to support a smaller radius, but to a greater tonnage and possibly a higher risk of marking/cracking. Tooling selection should be based on the entire part requirement.
Q5. How to know when to change the Press brake tooling?
Inspect tools for cracks, chips, dents, excessive wear and loss of straightness. If an identifiable localized bending defect is not present, but a tooling defect occurs repeatedly causing the defect, it should be investigated.