Avoid speed bumps at the press brake

A hang-up in the bending department can throw a wrench into a press brake operator’s workday. Here are some efficient strategies. Getty Images

The press brake department is the heart of many a fabrication operation. The elongation bending creates governs the blank size upstream in cutting, and the precision of forming governs the efficiency of welding and other processes downstream.

Bending also requires fine-tuned information-gathering protocols. Without those protocols, troubles in bending can be a significant speed bump to product flow and overall throughput.

So how does an operation fine-tune its information gathering? To answer that question, The FABRICATOR spoke with Jonah Higgs, a longtime fabricator who is currently the technical services leader at Schofield, Wis.-based Applied Laser Technologies, and also the creator of Bend Genius, a web-based tool to improve a shop’s precision bending performance, allowing jobs to sail smoothly through cutting, forming, and ideally, all the way to the customer’s receiving dock.

As Higgs explained, “We either have to remove the speed bumps from the process, or we’ve got to put up the appropriate signage that says, ‘This is a speed bump, but we’re warning you it’s a speed bump, so there’s no surprise.’ The speed bump is built into the fabrication strategy. This allows my technical teams to build problem-solving strategies before they turn into emergencies.

“When you boil it all down, smooth flow comes down to one thing. It’s about minimizing surprises.”

Who’s Accountable?

Higgs has a passion for bending and can opine with utter fascination about how a specific material alloy forms over a certain kind of V die. But, he also realizes that expecting everyone to learn such technical intricacies simply isn’t realistic.

“Part of removing the speed bumps from the bending process is making sure you’re giving your team the best tools. Bending has specific risk factors that need to be identified before parts arrive at our brakes, so our front office people need to be able to spot these problems early. Technical training is important to establish a baseline of understanding for our teams, but most of today’s workforce will not retain, or will struggle to apply, these rules and formulas.

“As the owners of technical rule sets, it’s our responsibility to arm our teams with the tools that take the guesswork out of their jobs. Engineers love an opportunity to get out their calculator and crunch some numbers, but it is not fair for us to expect that from the rest of our teams.

“It’s easy to get angry at sales, estimating, and design teams for missing something that causes a speed bump in manufacturing, but disciplinary action and constant retraining are not the solution. It’s our responsibility to equip our teams with the tools that make it easy for them to know when they’re safe, and when to ask for assistance.”

Higgs added that this perspective has in a foundational manner changed the direction of his management style over the years. He recalled espousing details on flange lengths and V-opening-to-material-thickness ratios to various shop personnel, from operators to estimators, only to be met with blank faces and tired eyes.

It’s about identifying who excels at what. A shop needs people with knowledge, but just as if not more importantly, it needs the people who execute the day-to-day tasks that keep the business profitable. “On the one hand, we have seasoned fabricators who are well-versed in the technical details,” Higgs said. “But our job is really to support the people who are doing the work”—that is, those who operate the machines and make part flow happen.

He even goes so far as to say that the skilled labor crisis is directly linked to the tendency of the current workforce to place higher value on speed than on rote knowledge. “We see our workers using cellphones to look up answers to questions that once required hours reading a book or sitting in a classroom. Deep technical training and data retention are becoming things of the past. The new workforce will work as fast as the tools we can provide for them.”

Expertise is needed; a fabricator simply cannot function without it. But education is a two-way street. People need to be receptive to new information and eager to learn. Brake operators might not be fascinated by going deep into the weeds of bending, but they might be fascinated with other aspects of the fab shop.

Thing is, you’d never know if a technical lead keeps pushing technical details that the operator isn’t interested in learning. A technical lead expecting an unreceptive operator to learn anything and everything about bending becomes the fab shop’s Sisyphus, pushing the rock of bending knowledge up an unsurmountable hill, forever going nowhere.

What Kind of Fabricator Are You?

Fabricators aren’t a homogenous bunch, and Higgs conceded that his information-gathering approach for bending doesn’t apply to every one of them. The approach mainly applies to precision fabrication job shops and contract manufacturers, those whose business model involves pushing the precision potential of bending, and where customers might require the forming department to hold tolerances of within 0.010 or even 0.005 in. At these fabricators, processes on the floor and in engineering are geared to handle serious precision-bending challenges.

This approach might not make sense in some operations. First, the market has plenty of room for fab shops that measure most parts with tape measures, not calipers. “I recall speaking with one fab shop owner who told me, ‘I don’t think we ever had a part we couldn’t bend.’ And I asked him, ‘What do you mean?’ It turned out they just weren’t a precision shop,” Higgs said. “They measured their parts with 25-ft. tape measures, and if parts are within a quarter inch, they’re fine.”

Picture a precision bending operation as a one-way highway with guardrails on either side. The middle of the highway is the bending operation’s sweet spot, its technical strength. Anything near the guardrail is a challenging job.

Depending on the shop and the markets it serves, a custom fabricator with a dynamic, high-performing bending operation—that is, a wide highway with flexible guardrails—can differentiate itself by quoting jobs others wouldn’t dare to touch. This isn’t because one shop’s capabilities are better, just different, all based on the tooling, equipment, and expertise a bending operation has.

Regardless, before a shop establishes its communication strategy, it must determine which jobs are sweet spots, right in the middle of the road; which approach the guardrails; which go beyond those guardrails; and how far beyond those guardrails the shop is willing to go.

“For instance, maybe your shop does a lot of hemming,” Higgs said. “Or maybe you work at a short-flange shop.” A job that calls for a narrow flange might represent middle-of-the-road work for certain fabricators yet approach the guardrails for others.

Levels of Technical Aptitude

Once a fabricator defines its technical strengths and weaknesses, it then can define the kinds of people who work in the shop, both in estimating and in the press brake department.

Some operations might try their best to impart to their front-line team—the CAD technicians, estimators, and salespeople—varying levels of deep forming knowledge. “What I’ve found through the years, however, is that forming requires a high level of technical aptitude in one operation, the press brake,” Higgs said. “But estimators need to look at blueprints and think about every single operation on the floor. Normal people don’t have fun digging down into the technical weeds of press brake work.”

Exceptions abound, he said, but for the most part estimators don’t have the interest or time to dig into the weeds—and that’s a good thing. The job in estimating and sales is to win work. If they continually think of every technical implication in every request for quote (RFQ) with a forming operation, they might not respond with a bid in time. And even if they were a wizard at the press brake and could respond quickly, estimators might try to squeeze in the guardrails, perhaps even turn down major growth opportunities, all in the name of optimal manufacturability.

At the same time, estimators need some ground rules. They should push to open the guardrails, but not ignore them completely. And they should consider at least certain basics. It’s a balancing act: Estimators need to quote a broad range of jobs to ensure the shop can grow, but they still need to perform a few basic checks—what Higgs calls his “different levels of bending fundamentals.”

Level I: Setting the Foundation

The first level deals with what happens to sheet metal as it’s formed inside a V die. He emphasized that these are just top-level fundamental checks that need to be completed before anything else.

Higgs added that who answers these questions depends on shop practices and its business development goals. For instance, some operations might have salespeople or account managers answer all Level I questions before passing a job on to an estimator, who delves into the details covered in Level II. Regardless, answering these questions as early as possible—and certainly before a job hits the floor—will help plan for or even eliminate any speed bumps to work flow.

V-Opening-to-Material-Thickness Ratio. As Higgs explained, “You need a set range.” Fabricators can turn to various sources for rules of thumb, including Steve Benson’s Bending Basics column in this magazine, “but every company needs to adopt and share their own rule set when it comes to determining the V-opening-to-material thickness range.”

That’s because every precision shop has a different mix of products it forms. Also, the range for this ratio will change depending on the material grade and tensile strength. A vast majority air-bend, but special tools and processes can still alter the ratio beyond those found in typical air-bending operations. If the range doesn’t account for this, estimators could end up turning away work that the bending department could successfully form without much trouble.

Minimum Flange Length. “Now, we need to guide engineers and estimators to give me enough information to suggest the right-sized V opening based off the part we’re trying to bend,” Higgs said. “Then we need to make sure the part is designed with a flange that’s long enough so we can bend it in that tool.”

Again, this can vary depending on the kind of tools a shop has. The estimator doesn’t need to know the intricacies: like, say, a certain bull nose radius tool with a urethane bottom die having a step on the die shoulder that allows an operator to form effectively with no minimum flange length. As Higgs explained, Level I is no place for such detail. All estimators need to know is if the flange is possible to form with conventional tooling.

Is the Inside Bend Radius Critical? “Some customers care less about the inside bend radius, some care a lot,” Higgs said, “because they design their parts to very close tolerances because, for instance, of how one sheet metal part might interact with another part in an assembly.”

In an air bend, the radius forms as a percentage of the die opening. What percentage goes back to those technical rules of thumb that, again, estimators and even others in the front office don’t necessarily need to know. But the earlier a fabricator knows whether bend radii are critical—whether the called radii on the drawing are needed within a certain tolerance or are just there for reference—the better.

How Close Are Holes and Other Cutouts to Bend Lines? According to Higgs, estimators should look for holes and cutouts to check how close any of them are to bend lines. “Is the part tapered on one end? Does it have holes or slots? What passes through or gets close to that bend line?”

Like everything else in Level I, estimators just need to know a range. This is an information-gathering stage only. A shop might, for instance, have wing dies that can form certain bends across holes and other features just fine. But those tools might not be available at every brake, and besides, the tools might not work in every situation. Regardless, those details don’t matter at this stage. Simply knowing how close holes and other cutouts are to bend lines dictates what technical checks are required.

Can You Accommodate the Bend Angle Plus Springback? As Higgs explained, this question can be particularly critical if the vast majority of angles the brake department forms are 90 degrees. A “non-90” bend can make determining other bend variables more complex.

Bending acute angles can be particularly problematic. For instance, what if an operator needs to bend a part to a 30-degree internal angle? Does the tool set—including the space in the die opening—allow for the depth of penetration to achieve that angle plus the required overbend for springback?

Again, a shop need not dive into the weeds here. At this stage it’s about defining ranges. Estimators and engineers know the range of easily bendable angles (considering bend angles alone, not potential collisions or obstructions, which occur in later technical checks). If they see an angle on the drawing outside this range, they flag it for further technical review. If everything falls within a defined range, they can progress.

What’s the Bending Tonnage? “I need to make sure the tools and press brakes can handle the job,” Higgs said, adding that, of course, this should be one of the last Level I considerations. That’s because tonnage hinges on the material type, the material-thickness-to-V-opening ratio, the die chosen to produce the inside radius the jobs needs (if the customer cares about radius), bend lengths, and the tonnage capacities of the press brakes on the floor.

“That’s Level I,” Higgs said, “which covers the fundamentals. We’ve got to get these factors out of the way before we can have a conversation about the things that make a particular part unique. If you’re stuck here, you need to resolve the problems before you go on to the next stage of the dance.

“Just the Level I data already might seem too heavy or technical for most people,” Higgs said, “but these are absolutely critical to preventing loss of production on the shop floor.”

Level II: Now, the Fun Part

“This is why a lot of people work in this business,” Higgs said. “It’s the fun, abstract, and allows us to think creatively.”

This level mainly involves part geometry factors that could lead to tool collisions or part handling problems. Higgs added that, yes, many of these problems can be caught by offline bend simulation software that’s becoming more common across the industry, but he warns that the software is a finite resource. “Programmers running simulations need solid models,” Higgs said, “and shouldn’t be spending all their time trying out part after part, especially if the jobs haven’t been won, and especially if—with a bit of training—engineers and estimators could simply see problems by quickly looking over a 2D blueprint.”

Where Are the Bends in Relation to Each Other? This question helps catch some basic bend sequence challenges. Say a part has one up-bend after another after another in the same direction, or perhaps a sequence of down-bends. Or perhaps the part has a series of positive and negative bends. What if two up-bends create a tall, narrow channel? Will available tooling be able to access the bend? What’s the risk of collision?

Offsets apply here as well. Is an offset so odd that it requires a special tool? Or is it a conventional offset, but one that—due to part handling challenges—really could benefit from a dedicated standard offset tool set? Or could it be performed with two hits with a standard punch and die? Also, how critical are the offset’s bend angles? A critical offset dimension—like one that requires a specific angle or radius—might require further review and, more than likely, a customer call.

Can the Operator Handle This Part? “Here, we consider part handling challenges,” Higgs explained. If a large piece has a narrow edge flange, how will the operator (or operators) support the part as it swings upward? Is it too thick and heavy or is it thin and floppy? Either extreme can create accuracy issues.

Similarly, how will the operator gauge the part? If, late in the bend sequence, the part has no flat area that can slide against a backgauge finger, the piece might need special gauging.

Are There Unusual Alloys or Finishes? The material grade and thickness enter the conversation from the get-go, right when factoring in the radius-to-die-opening ratio in Level I. Material considerations in Level II come into play when the job calls for the unusual: perhaps aluminum diamond plate, armored plate, or perforated material.

What’s unusual depends on the shop’s part mix; what’s near the guardrails for one shop might be right in the center of the highway for another shop. “Regardless, addressing this allows you to develop a plan,” Higgs said, “so that when the job hits the shop floor, you have no surprises.

“At this point, it becomes fun, because it requires serious brain work,” Higgs continued. “It can get complicated, but Level II really can be boiled down to a simple question: Does anything about this part look weird?”

Level III: The Really Fun Part

At this point, most obvious problems have been worked out. Everyone knows what if any speed bumps a job might present; the only question now is how large those speed bumps will be.

These jobs might require special tools. If the special tools will be designed in-house, toolroom personnel need to collaborate with bending personnel to determine the bend sequence, potential collisions, and other factors. The same thing goes if the tooling is outsourced.

Some shops might choose to use a prototype or pre-production area—staffed with the fabricator’s technical gurus—to test or qualify challenging jobs before they hit the shop floor. Alternatively, a note might be placed on the job traveler, telling the press brake operators to contact the technical lead before starting the job.

Of course, this happens only for a select few jobs, and it’s an expected speed bump that’s accounted for in the schedule. By no means is it a surprise.

Such collaboration, Higgs said, can create some of the best workdays a press brake operator can experience. “I’ve found that press brake operators love it when they get to work with a lead person on a technical project. And as a technical lead, I’ve been there. We have fun, challenge each other’s solution on how we should handle a problem, and do high-fives when we’ve found a new way.”

Higgs paused, then chuckled. “Let me tell you, those are good days.”