Tooling with programmable, adjustable height provides access to internal bends, such as tabs that are otherwise difficult to access.
With press brakes, it’s easy to see what’s happening. With folding machines, it’s not always so easy. Laying the workpiece on a flat table, clamping it, and wiping or rocking a tool against it to form a bend is easy enough to follow. Where it gets interesting is in manipulating the work and producing certain features on parts. Add automation, and it requires a close look and some background about how the machines have developed, to judge where they’re best employed.
Fab Shop asked Bill Kennedy, VP of RAS Systems USA, to walk us through their evolution and to clarify how and where the latest high-tech folders compare with press brakes. RAS builds folders ranging from models that are largely manual to the most highly automated types, and Kennedy spent 40 years selling press brakes, so he’s a go-to authority for comparing different approaches to bending:
“If we were in Europe and visited a sheet-metal fabricating shop, you would likely see a couple of press brakes and a couple of folders. You wouldn’t see a bunch of press brakes alone. We’re a little bit behind the curve in the U.S., and one of the main reasons that we’ve been a little slow is that, if you go back ten years or more, the people bending metal with a press brake were actually coining it. Punches were being bottomed in the dies and displacing some metal. Sharp bend radii were a lot more common, and folders don’t bottom like that.
Radii evolving by design
“Since the evolution in air bending, driven by engineering and product design, minimum inside radii of 1.50 times material thickness are more common with press brake bending now. That’s really quite large compared to how things were being done years ago. And that’s where folders come in.
“You can still get tighter radii air forming with a brake because you have more tonnage.Again, that’s less of an issue now. The tradeoff is the gains made with the folder: the part handling, the accuracies, the quick setup. They are extremely quick to set up. Typically you buy one set of tools and the geometry of those tools will allow them to do a lot of parts.”
Kennedy points to RAS’s FLEXIbend as an example. “Look at the tooling. They are hardened and ground, segmented tools that can be slid left or right; taken off; or put on in any combination you want. We don’t sell a lot of tooling. Folders don’t have the appetite for tools that press brakes do.”
A few more distinguishing points: On one or the other side of the folder is the table, which supports the full weight and size of the workpiece material. Folders make handling large blanks easier because they lay flat on the table and don’t have to be held while they’re bent. Thus, operating can require less labor. Press brakes tend to be better for small parts, although folders are intruding in that area, as well. Folders are limited to sheet metal; you don’t have the tonnage to handle thick workpiece stock. Press brakes can handle thicker material. Folders can more easily make long, tightly-spaced flanges, even internal flanges near an edge, as on door jambs, computer racks, and similar parts. “The more complex the part, the better the folding machine is,” says Kennedy. “Multiple angles within a part, and many bends, are handled better on a folder just simply from a manipulation standpoint.” Brakes can cycle faster, although that doesn’t necessarily mean greater productivity. Applying a broad generalization, folders can produce greater accuracy and less scrap.
The trend toward larger-radius bends works in favor of folders. They can’t coin like a press brake that’s set to bottom the punch in the die, producing a very sharp bend, but contemporary product design has reduced the need for it.
So it’s a tit-for-tat, with each machine type having advantages in one application versus another. Kennedy says he really enjoys analyzing customers’ applications because he often can see where folders will do a job better, which the customer hadn’t thought of. Imagining what folding machines can do is not easy unless you’ve looked at a lot of applications and solutions.
But back to new developments and the evolution: “Our popularity’s growing in precision fabricating,” says Kennedy. “And it’s coming from the push for lean manufacturing. We can truly set up and run parts in ones and twos. Press brakes start catching us at 150 parts. When we go to the more advanced folders, to automation, there’s no catching us. And when you start getting into the part-size range of four or five feet, and complex parts, you should be at least entertaining the idea of using a folding machine.”
Evolution step one
But there are markets and machines for all levels of automation. Starting simple, Kennedy points to the company’s FLEXIbend. It has CNC features but the operation is still operator-dependent:
“Here’s a machine with which the operator is totally involved, and it only bends up,” he says. “This is where the evolution started.
“The FLEXIbend, though, also has ‘intelligent crowning,’ which was introduced around ten years ago. When you change material thickness and tell the controller, the machine makes adjustments for that material thickness.When you then bend that new part for the first time, the folding beam will come out 10 degrees and then a computer-controlled, motorized adjustment is made in the crowning. It does that individually for every bend length, because every bend length is going to have a different deflection. The program also compensates for the part configuration and it knows the material thickness. Once it’s gone through the adjustment, which really is pretty quick, it’ll do it for every part.”
Even at this “step one” level of complexity, the functions and features of the machine are more involved than these few highlights, and a video is a far better way to appreciate them than to try to explain it in words. You can see them in this video.
Step two
RAS System’s XLTbend is a machine that bends up and down. There is no need to flip the work for making reverse bends. It also incorporates a “beam-in-beam” folding-beam design that eliminates the need for crowning adjustments, while producing much greater straightness in bends.
It also incorporates several more automation features. It has a series of suction cups that takes the part from the operator (they can be seen best in this video of the RAS UpDownCenter). The only operator involvement occurs if the part needs to be rotated.
The XLTbend was introduced just last November, and its mechanical features are numerous. This is where folding machines become more difficult to follow than press brakes. To appreciate the features, you have to start with the geometry challenges involved in making boxes, panels, and cassettes.
For example, when bending up and down without flipping the part, the tooling and folding beam have to be able to clear a pre-bent flange when they’re folding a flange in the opposite direction. Bending internal features such as welding tabs – one of the strengths of folders – is made possible by a tooling innovation that allows some tools to move up and down during the cycle, under CNC control, to get inside of other elements of the workpiece.
These complexities are necessary to achieve application flexibility in the machine. Traditionally, folding machine features have been tailored to specific, narrow ranges of applications. This narrowness is being overcome by innovations in the mechanical and tooling features, and, extensively, by advanced CNC. They are still designed around classes of work, however. As Kennedy says, “All these features have been designed with products in mind. Instead of us making the machine and telling people, ‘This is what we have; see what you can do with it,’ we go to them and say, ‘We know these are your problems. This is how we can solve them.’”
The XLTbend includes RAS’s all-out CNC-program-streamlining, Bendex3D software, which they call “One-click programming.” Intelligence is built into in the machine software, so either the operator or an off-line programmer just imports STEP, DXF, or GEO files (which were previously checked for potential collisions), and the machine-programming is done. That’s all it takes to program the complete setup and bend sequence automatically.
When alternate strategies are available to form the imported part, the CNC shows alternative sequences and ranks each on a 5-step rating scale to help judge the best strategy for production. The operator has the option to simulate each strategy in 3D from any perspective, and to zoom on the simulation. Once the operator evaluates and selects a strategy, all that remains is to press the “Start” button to begin forming.
Whether it was the proliferation of mechanical features that drove the need for this intelligent programming, or whether it was the other way around, we didn’t ask. Regardless, this is what makes it possible to combine one-part programming, automated back-gauge setting, work-feeding, automated tool movement, workpiece versatility, and high productivity. The concept reminds us of the stealth fighter planes that are impossible for a human to fly without their computers. In the case of the folder, it’s almost like autopilot.
Closely-spaced bends are a danger to an operator’s fingers. With automated work-feeding, the operator is kept in the clear.
Step three, then quick-step to step four
We can keep step three short: it’s the UpDownCenter, which, conceptually, is similar to theXLTbend, plus an automatic toolchanger. Now we’re getting close to hands-off automation: the operator just has to rotate the part, if needed. We’ll take a quick step to four, RAS’s ProfileCenter.
“Again, we’re trying to find solutions for difficult products, and the ProfileCenter was originally designed for door jamb manufactures,” says Kennedy. “These are very tedious and dangerous parts to make on a press brake. It really requires flexible and automatic profile bending and it’s hard to automate — or it has been really hard to automate in the past. Very large manufactures are still using press brakes and they have operators involved. These tight profiles cause the operators fingers to be in some very dangerous places, and the same applies to similar tight profiles. For example, big computer racks.
The ProfileCenter is tailored to make long, closely-spaced bends, up and down, for such applications as making door frames and computer-rack frames.
“The parts have a lot of positive/negative bends, so the bending is going up and down. The ProfileCenter takes the part and handles it any way you want to do it. If you want to feed it with robots, you can. There are so many different ways of feeding parts, and, typically, the automation is very customized. You really have to watch this one in a video.”
It’s these combinations of bends, exampled here with some closely-spaced and tedious folds, many involving a reversal in direction, that is the forte of folders.
There is more to the company’s machine lineup, including large and small fully automated machine models. We watched a lot of videos to prepare for this article. Advanced folders can be intimidating to write about, because there are so many things that are hard to explain in words. This editor is a former job shop owner who recognized right away that they are not machines you can dope out on your own, with articles, brochures and videos. It requires real application experience – in other words, a good sales engineer – to see the possibilities for any given application. This reflects what Bill Kennedy told us, too, and he has 40 years of background in bending and folding.
But the videos we’ve embedded in this article should give you an idea of how many possibilities there are to take a job you’re doing on a press brake and convert to a folder. The accuracy, repeatability, automation, and safety potentials have to be appealing.
It’s worth a call and a visit. It could be good for your bottom line.
