The big job of bending big metal on a 2,000
Merrill Technologies Group, Alma, Mich., installed this 38-ft.-long, 2,000-ton Accurpress press brake in 2011. It has even bigger bending plans in store this summer when it gets its new 4,400-ton brake up and running.
Press brake operators might share similar job descriptions, but there are some big differences in the scope of their daily routines, specifically for the select few that operate large-tonnage brakes.
Someone in front of a 350-ton press brake with a 10-ft. bed could end up doing 200 to 300 hits per shift. A press brake operator running a 2,000-ton machine might only make a few hits an hour before having to reposition a large plate.
An operator on a low-tonnage press brake sits right in front of the brake, trying to keep pace with the machine and avoid tripping the light curtain. An operator on that large-tonnage machine stands to the side of the press brake, minimizing the possibility of injury should the plate fracture during the bending process. (It should be noted that the same risk exists with lower-tonnage press brakes as well.)
Shops that have these giant press brakes are in a small fraternity, and that’s by design. These large pieces of equipment are looked upon as a competitive advantage. These shops want to be able to bend metal that other shops can’t.
Merrill Technologies Group, Alma, Mich., installed a 38-ft.-long, 2,000-ton Accurpress in the latter part of 2011, hitting its first parts in January 2012.
At the time, Merrill invested in the press brake because it was looking for a machine that could form 2.5- to 3-in. plate, which was a struggle for the 750-ton brake it had at the time. The metal fabricator also was looking for a brake with a long bed to take on jobs that wouldn’t fit on the 750-ton brake’s 12-ft. bed.
More than a decade later, Merrill has gotten a lot of mileage out of its big brake, but it’s thinking even bigger. It’s in the midst of installing an Ursviken 4,400-ton brake with a bed that’s almost 26.2 ft. long.
Brian Engelhardt, the plant manager for Merrill’s Alma, Mich., fabricating facility, which will be home to the big brakes, is no stranger to bending. As he set out on his manufacturing career, he spent a good amount of time in front of press brakes, albeit much smaller than the ones that are the subject of this feature.
Andrew Welsh has been working with the company’s 2,000-ton brake for the past eight years. Like many in the metal fabricating industry, he got his bending education from someone that had spent a lifetime in the industry. In this case, that expert was Mark Szelogowski, who worked closely with Welsh before retiring.
“I got about three years of training from him,” Welsh said. “He knew a lot because he started on press brakes before they even had computers on them.”
Andrew Welsh has been working with the company’s 2,000-ton brake for the past eight years. A lot of what he learned about the job came from Mark Szelogowski, a long-time press brake operator who recently retired.
That’s actually a noteworthy observation because Welsh is a part of a generation that has come to expect some sort of CNC on press brakes. While these large-tonnage machines look very much like their predecessors from the 1960s or 1970s, the machines from the early 2010s probably have more in common with the more advanced bending machines of today.
For example, the 2,000-ton press brake has control technology that guides Welsh’s tooling choice. After reading the blueprint that’s been prepped offline, Welsh plugs in the key information, such as material type and thickness, and the control software recommends the size of the punch and the bottom die.
The large brake also has a heavy-duty, 6-axis backgauge, which plays an important role in delivering repeatable bends. Welsh said the backgauge is a real help in knowing that the heavy workpieces are square in the press.
The scheduling and operation of the large press brake are where things really differ from working on small press brakes. For instance, a changeover for something this big can last a couple of hours, instead of 10 to 15 minutes.
“If it were my world, I’d just like to set it up with an 8-in. punch and an 18-in. bottom, and I’d bend as many parts as I could,” Welsh said.
But that’s not how it normally goes. Engelhardt said a 30-day schedule provides Welsh and others an idea of what jobs are making their way through the shop. With that in mind, everyone knows what has priority because of impending delivery dates. That might mean the large press brake is used to complete one job, and then immediately changed over to do another one. Then there might be days where two or three jobs, all of which are high on the priority list, might be done all at once because they use the same tooling.
“All the divisions of Merrill, we have one united goal as a company as we operate on the same schedule. That means this press brake follows that schedule, just as all the other departments,” Engelhardt said.
So, changeover is inevitable. It just takes a little more time and care.
Welsh said that the tooling for the large-tonnage press brake is typically about 10 to 12 ft. long, but some get to be as long as the length of the brake. Welsh said he can handle some changeovers on his own with the help of a nearby crane, but when necessary, he’ll have the forklift come over when he needs assistance.
“We now have a fork truck dedicated to the department,” Engelhardt said. “That was part of our process improvement effort. We could call it over as needed. But based on the times that we had to wait for it, we just said we’d dedicate a fork truck to the area.”
The changeover process is something that occurs regularly because the bending department sees a large number of new jobs on an annual basis. Welsh said that’s just the way he likes it because the variety of new projects provides him with new challenges on the brake.
Working from the blueprint, in addition to what tooling is needed, Welsh said he gets an idea of how the part will be manipulated to complete the job. He also knows that he can rely on the upstream processes, such as blank cutting, to deliver parts that are ready for the brake. For instance, blanks cut from armor plate need to be cut in such a way that the grain is running perpendicular to the bend line so that a stronger bend occurs. (Bending across the grain reduces the chance that cracking will occur.)
“We typically use an overhead crane for material handling,” Welsh said. “We usually hook up most material with plate clamps—1-, 2-, or 3-in. clamps. If it’s really thick material, we have one of the welders weld a lift-eye on the plate, according to the WPS.”
When the plate gets airborne, that’s when everyone gets zoned-in on the job. Even though he’s been at it for several years, Welsh said he doesn’t take the process for granted because he’s well aware of the potential for injury.
That’s why the foot pedal has a 60-ft. cord attached to it. The operator shouldn’t be close to the workpiece as the bend is taking place.
That doesn’t mean that the press brake operator, and anyone else assisting, don’t engage the plate. One or two people might be needed to push the plate into position against the backgauge. Welsh explains what happens next.
“Once you get it in there, you get a little pressure on the piece and that puts pressure on the chain. When that die and the plate are touching and the plate isn’t moving, you can put a little slack in the chain. Then the bending starts. During that time, you keep that chain taut,” he said.
Like so many other aspects of metal fabricating, Welsh can hear if the process is going well from the sound of the material being bent in the large-tonnage press brake. When he hears a high-pitch crack during the bending of steel armor plate, he knows the material has cracked. (On the other hand, the cracking of aluminum armor plate sounds like a whoosh of wind coming through the window of a speeding car, according to Welsh.) Of course, the goal is not to hear something so dramatic when bending this thick and challenging material.
“Merrill does a lot of work with the customers and engineers upfront. Our engineers know exotic materials and the new high-strength alloys. They know how we’ll have to deal with issues like springback,” Engelhardt said. “That’s why customers ask us to push material limits to achieve a tighter radius in the formed parts.”
If the workpiece has to be flipped or rotated after the initial bend or bends, the injury risk grows. Welsh said that’s where experience and patience pays off.
“Safety is always a top priority over here. Because you’re dealing with so much tonnage, you have to know where you need to be. You can’t be in the wrong spot,” he said.
Safety also played a big role in deciding what type of features are on the new 4,400-ton brake. Automation isn’t only for low-tonnage brakes.
“One of the riskiest moves we make is flipping and rotating the plate to get the next bend,” Engelhardt said. “So, we established criteria for the design of the new press brake. Because of that, Ursviken came up with a solution to flip a 10,000-lb. plate between the side frames.
“There’s also front and backgauges that will coordinate with each other to move the material around for the next bends,” he added.
No manual intervention will be needed to make those moves when the new brake is up and running. One person can operate the brake and watch as a part as large as 10 by 20 ft. and up to 10,000 lbs. is maneuvered into position by automated means.
The new brake also will see limited tooling changeovers because of variable die technology. The die will be able to go from a 4- to 36-in. opening. Any large part that needs a large die opening is going to be bent on the new 4,400-ton brake.
“Right now, we’re focusing on certain families and parts to take them off the old machine and put them on the new one to help reduce fatigue over time on the old press brake,” Engelhardt said.
Once that new press brake is operational this summer, Merrill plans to overhaul its 2,000-ton Accurpress to get it as close to where it was the first day it was installed 11 years ago. It’ll also be moved to the front of the fabrication facility, closer to receiving and the burn tables, which should provide better flow of workpieces. The 4,400-ton press brake is to be located in this same spot.
The relocation of the large press brakes clears out space in the section of the facility with the high-bay ceiling. Engelhardt said the move will provide additional space for very large fabrication work.
In the meantime, Welsh is keeping his eye on the assembly process for the new brake. He’s ready to see it in action.
“I can’t wait until it’s set up. I want to put something in there and bend it,” he said.