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Does your shop need a custom press brake tool?

Asking these four questions will help uncover bending options

press brake tool inserts 3D printing

FIGURE 8 These 3D-printed die inserts help achieve specific part requirements or mar-free bending.

A print lands on your desk, and the bending requirements look unusual. It doesn’t look like any tool from your toolroom or even an off-the-shelf tool from a catalog would really work. Does the job require a custom press brake tool? Historically, the application analysis has involved the usual suspects, including accuracy requirements, volume, throughput, and worker ergonomics.

Say the print calls for an offset with an unusual radius and angle, and each needs to be formed within tight tolerances. Such accuracy requirements might lead you to a specially made offset tool, particularly if the part is a high-volume one. Even if the tolerances weren’t so tight and an operator could use a conventional punch and V die, he would probably find it difficult to flip the large part to form the offset’s positive and negative bends. This would lead to poor ergonomics and potentially abysmal throughput.

Today those accuracy, volume, throughput, and ergonomics factors are as relevant as ever, but new approaches to special press brake tools have broadened the options. These include 3D-printed inserts and even custom backgauges. Special adapters have also made some form tools, originally designed for the punch press, to work on the press brake.

Every strategy regarding special press brake tooling depends on the application as well as a fabricator’s available equipment and forming expertise. Regardless, the strategy should start with a few questions that, if answered well, should reveal the gamut of special tooling options available. Once you know your options, you then can determine the best path forward.

1. What is really important?

When it comes to press brake tooling, a quick phone call to a design engineer can save so much money. Sure, some prints are what they are; if they call for a specific angle and radius within a specific tolerance, that’s what they need, end of discussion. But this certainly isn’t typical. Such assumptions might make a part far more expensive than it needs to be.

Consider a print calling for a 10-in. radius formed to ±0.002 in., a tolerance that—with a modern press brake and a carefully made custom tool (tested and reworked umpteen times)—might actually be possible. But is it really needed? A quick call to an engineer might reveal that the large radius is there purely for strength purposes; there’s really no need to hold the radius to such a tight tolerance (see Figure 1).

Offsets are another prime example. Say a print shows an offset as two 90-degree bends and specifies a height. Sometimes the offset height might not be a standard dimension, like 0.250 in., but instead something like 0.236 in. A chat with the design engineer might reveal that, yes, that offset height of 0.236 in. is critical, but the 90-degree angles aren’t.

2. Can we bend the part with a standard tool?

Once you know the true manufacturing requirements, you then can begin to assess the tools you could use to perform the job competitively and safely. “Competitively” and “safely” are the key words here. Yes, you could have a brake operator flip a large part to make the second bend of an offset, without relying on a dedicated offset tool; or perhaps bend a narrow edge flange into a large panel, swinging the large piece over his head. But both of these scenarios involve concerns about safety, quality, and efficiency.

Here’s where worker ergonomics enters the equation. Wiping and rotary tools allow operators to insert a piece horizontally, while the tooling folds the edge flange up or down. The act of wiping does require that the tools have thrust plates, which counteract the horizontal forces during the bend cycle (see Figure 2). Rotary tools use a rotating cam with a V opening (a so-called Pac-Man tool) to fold an edge flange around an anvil punch (see Figure 3). Because the cam rotates throughout the bend cycle, the point of contact leaves minimal if any marks on the outside of the bend.

And sometimes standard tool sizes are indeed the way to go. Consider again that offset application with the critical height of 0.236 in. but with noncritical bend angles. They’re specified as 90 degrees, but they don’t have to hold 90 degrees exactly. In this case, you could use a standard 0.250-in. offset tool, control the ram height to leave a 0.236-in.-tall offset, and you should be good to go, depending on what your bend angle tolerances are (see Figure 4).

Stiffening rib forming

A custom tool set these days might not be entirely metal. This 3D-printed tool forms a stiffening rib.

3. What about punch form tools—without a punch press?

Years ago many fab shops punched in-house but sent some work out for laser cutting. Today many fabricators do the opposite. They’ve built up their fiber laser cutting capabilities but sold their old punch presses. Then they see a print that calls for a form that could easily be made with (of course) a form tool on a punch press. So they end up sending the work out to another shop that has a punch press with the right form tools. Or they pass on the work entirely, simply because that one forming operation makes the job unprofitable.

In other cases, parts that could be most efficiently formed on a punch press sometimes have job routing issues. A shop might just have one punch press that’s tied up with a large job. Unfortunately, another small job has a few extruded holes, but there’s no immediate capacity on the punch press. The shop has plenty of cutting capacity on its lasers, but those lasers can’t form the extruded hole.

Punch form tooling also has another advantage: price. Say you need to form a small louver. If you don’t have a punch press, your only choice traditionally has been to make or order a louver punch and die set for the press brake (see Figure 5). Unfortunately, even a standard louver punch and die set costs more than a punch form tool set (which uses less tool steel) that could accomplish the same thing. The same applies to small hinges, flanges, lance-and-form clips, and more.

Today, however, some punch form tooling—specifically certain TRUMPF-style form tools size 2 and thick turret (E station) and smaller—can be mounted to an adapter and used on the press brake. If, say, you need to form a small louver or emboss, you simply slide the blank between the louver punch form tool set; the blank edge hits a stop integrated into the tool, and forming commences (see Figure 6).

In some ways, punch form tools actually become more capable once they’re off the punch press. No longer restricted by the punch’s stroke height, form tools on the press brake can create very high forms. For instance, a flange form tool (with a rotating Pac-Man die folding the sheet against the anvil above) can form flanges far higher than would be possible on the typical punch press.

Note that a press brake is a forming machine, not a punching machine. The press brake adapter can use punch form tools as well as some chisel point tools, which effectively stamp an eighth shear (a shear that’s an eighth of the material thickness) onto the material surface. But the setup isn’t designed to withstand the stresses of punching and the subsequent snap-through forces.

Fabricators have used C-frame tools and other methods to punch on press brakes for years, so it can be done. But if you have a choice, try performing the cutting operations on another machine, such as a laser. The blank arrives in the bending department with the cutting operation complete; the modified punch form tools at the press brake perform the forming only. In this sense, the “punch form tools” are modified to become “form tools”—same as before, just without the punching. For instance, a lance-and-form tool wouldn’t lance (again, the cutting would already be completed on the laser), it would only form.

Custom form tools—designed for the press brake but machined out of punch tooling stock—open up a variety of possibilities. Consider a small component with multiple flanges that would be difficult or impossible for an operator to manipulate even with the smallest conventional brake tooling. A custom form tool can be made of round stock (hence its lower price and lead time), mounted to a press brake bed adapter, and allow the brake to create a complicated component in a single stroke (see Figure 7).

When it comes to limitations using punch form tools on the brake, tonnage considerations occasionally arise, especially with large embosses in thicker stock that drive a lot of forming force into a small area. Such tonnage concerns are relatively rare, though. The main limits involve the size of the form. If the form requires more space than a punch tool offers, then using a form tool adapter for the press brake isn’t an option.

4. What about 3D printing?

3D printing opens still more options for custom tooling, especially when using composite and strong resin material with printing methods that create tools to high dimensional accuracy. The tools’ tonnage ratings aren’t high enough to bend thick, high-strength plate, but they’re becoming a viable option for a range of sheet metal applications.

Radius forming in sheet metal

FIGURE 1 This radius tool is used when a full radius is required before a flange (and, in this case, a closed hem). Today’s radius tools can be made to exacting tolerances, but it’s always best practice to determine what forming tolerance is actually required.

For instance, using printed V-die inserts can achieve either specific part requirements or mar-free bending (see Figure 8). 3D printing also has been used to reduce the cost or increase the flexibility of a custom press brake tool set, especially one that forms multiple bends or parts at once (see Figure 9). A single part might not have high enough volume to justify a complicated custom tool, but a part family might. An operator might use a printed tool with a steel base; to form another part in the family, the operator simply swaps out the printed portion of the tool with another variant.

3D printing has applications that go beyond the brake tools themselves. Consider custom gauging. Some jobs could be formed in a custom or even conventional tool set, but gauging them properly might be a bear. An operator might rely on pin stops or other setups, but making them work might require time-consuming process adjustments.

Printed custom gauges, however, can change the situation. They can be as simple as a gauge screwed onto the back of the tool body (see Figure 10). Or they can be as complex as a custom side gauge consisting of a steel bar with a printed “sheath” that has a profile matching a part’s side-gauging requirements perfectly. And, of course, that sheath can be swapped out with other custom-printed sheaths that modify the side gauge as needed.

3D printing can also help with part handling. Consider again the punch form tool mounted to an adapter on the press brake. It might be able to produce a small part quickly, but operators still need to retrieve the small formed part. This might take time. The operator might lose a few parts, and the pieces themselves might be a bit sharp and dangerous to handle.

To drive efficiency, you could print a chute and small container adjacent to the tool. The form tool could cycle, and the formed piece could then fall down the chute and directly into a small box that, when filled, is carried to the next operation.

Finding the Best Path

These four questions give you the available options. Which one makes sense for your operation depends on those usual suspects, including the part requirements (tonnage needed, accuracy of radii and angles), volume, demand consistency, and mix of technology on the shop floor.

If you have ample punching capacity and a large library of form tools, you’ll likely take a path that’s different than the one taken by a shop with several lasers and just one single-station punch. Regardless, knowing all the options will help reveal the best path to success. And today that path might include elements—like 3D printing and using punch form tools on the press brake—that were largely unheard of just a decade ago.

Editor's note: Check out the first episode of The Additive Report Advisor to learn more about what advantages and disadvantages additive manufacturing offer to metal fabrication job shops.

About the Author

Steve Brown

Bending Product Manager

12912 Farnham Ave.

White Bear Lake, MN 55110

866-752-6531