Big bending jobs lead to high-tonnage press brake
Michigan fabricator no longer outsources plate bending
When a fabricating operation serves customers in the defense, heavy equipment, mining, and power generation industries, you know they are working with really thick and high- strength material. It's a big job and requires big equipment. It's also the main reason that Merrill Fabricators purchased a 2,000-ton, 38-foot press brake.
Fabricating large metal parts and assemblies is a big business—both in terms of weights and dollars.
Merrill Fabricators, a division of Merrill Technologies Group, Saginaw, Mich., knows this firsthand as it has seen its business grow serving the needs of its large OEM customers. The metal fabricator routinely works with fabrications that weigh as much as 60,000 pounds for defense, energy, heavy-duty equipment, and mining applications. Merrill has 165 employees, including almost 100 welders, who work on these very large and complex parts over two shifts in the company’s 400,000-square-foot facility in Alma, Mich.
From an equipment perspective, Merrill is ready for jobs as small as a 5-lb. bracket or up to a 100,000-lb. mining truck assembly. It has a huge 15- by 60-ft. cutting table with high-definition plasma cutting capabilities and also oxyfuel torches for cutting materials up to 8 in. thick. For thinner materials, it can use a 16- by 31-ft. table equipped with both plasma and oxyfuel cutting capabilities or its laser or waterjet cutting machines. Merrill also has five robotic welding systems, one of which is a gantry welding table with a 12- by 12- by 60-ft. work envelop and a weight capacity of up to 100,000 lbs., and 119 welding power sources spread across the facility.
To ensure that it has a constant stream of manufacturing talent, the company established the Merrill Institute of Welding, an American Welding Society-approved training program designed to turn out shop floor-ready welders. (See “Waiting for welders won’t work,” The FABRICATOR, September 2011, p. 60, for more information.) The company already has welcomed at least 10 welders from its first two classes, which began in late 2011, and expects a steady stream of more trained welders as word spreads about the educational opportunity.
“We not only have the capabilities to do this large stuff. We have the skills to do this large stuff,” said Dale Betts, facilities manager, Merrill Technologies Group, which comprises Merrill Aviation and Defense, Saginaw, Mich.; Merrill Engineering & Integration, Saginaw, Mich.; and Merrill Tool & Machine, Merrill, Mich.
But one shortcoming did exist on the shop floor until recently: Merrill Fabricators had big bending capability, but it wasn’t big enough.
The company’s 750-ton, 12-ft. press brake could perform many bending jobs, but it just wasn’t powerful enough to accommodate jobs that called, for example, for 2.5- to 3-in. plate to be bent. Those types of jobs had to be outsourced to other fabricators in other states. In addition, Merrill wanted to jump into thicker and larger-diameter rolls that could be bump-formed only on a larger press brake.
So in early 2011 the decision was made to purchase a high-tonnage press brake that could help Merrill bring in those big bending jobs. It also was an effort to place Merrill Fabricators in a position where other fabricators would be pressed to match manufacturing capabilities.
“Investing in new technology, size, and capabilities that sets us apart from our competition” was really the focus, said Jeff Yackel, chief operating officer and vice president, Merrill Technologies Group.
A Really Big Deal
Despite a desire to do more complex roll forms, the Merrill manufacturing team knew it didn’t want a large plate roll former. It could perform only roll forming; Merrill wanted a tool that was much more versatile.
That meant a large press brake was the way to go, but how large? Merrill knew of longer press brakes in the area, one of which was 50 ft., but it was more interested in greater power. With the focus on high tonnage rather than bed length, that ruled out a tandem press brake setup. So the focus went back to the 3-in.-thick metal. If the press brake were to have the ability to bend a 42-in.-long piece of that very thick steel, how much power would it take? The press brake would need much more tonnage than the other 1,000- or 1,500-ton press brakes in the area could provide. That led to an interest in a 2,000-ton press brake.
As for the length, Merrill knew it wanted at least 30 ft. of clearance between the uprights, which would have put the length of the press at 34 ft.
After consulting with several press brake manufacturers, Yackel said, they decided to work with Accurpress, which had experience with high-tonnage press brakes, some up to 2,500 lbs., but not as long as 34 ft. The company’s willingness to work with Merrill’s project goals was a main reason the company stood out, according to Betts. As an example, he pointed to their desire to bump-form rings on the new press brake, and Accurpress’ suggestion to add a horn to accommodate such a task. The addition of the horn also added 4 ft. to the length of the press bed—stretching it out to 38 ft. total.
The plan called for delivery of the 2,000-ton press brake in late 2011. To prepare for the equipment’s arrival, Merrill had to do some foundation work, but not in the traditional sense that most metal fabricators are familiar with. Instead of digging deep into the earth, the company placed metal pillars in its basement. Because the facility was a former stamping facility before the fabricator moved in almost five years ago, it had a basement where scrap metal from the many stamping presses was conveyed for easy collection and removal. Several concrete and metal pillars measuring 14 ft. high, the distance from the basement floor to its ceiling, now stand underneath the massive press brake.
All Merrill basically had to do on the main floor was refill a hole where a stamping press once stood. It also added a new overhead crane with a “pitch-and-catch” arrangement, according to Betts. It can run as either one hook or independently as two hooks, one at 15 tons and another at 5 tons. Such an arrangement is helpful in maneuvering awkwardly shaped parts in the press brake.
Because of the large scale of the project, the press brake was assembled and painted on-site in Alma, Mich. Merrill struck its first parts in January 2012.
The fabricating team didn’t mess around. The first job thrown the press brake’s way involved heavy armor plating, which, despite its very strong metallurgical makeup, can be very brittle if bent recklessly. After that, the manufacturing team started throwing over some of its everyday mining jobs to the big brake.
“We knew that we could do 80 to 90 percent of our work on it. We decided that covered the sweet spot,” Yackel said.
No Simple Brake
The Accell 5200034/38 press brake (see Figure 1) is very large, but that doesn’t mean it lacks the sophistication of its smaller cousins. Merrill had goals of achieving first-time bend quality and consistency after that, and that doesn’t come without help from the latest technology.
“We want to be able to lead and be innovative and offer those innovations to our customers,” said Richard Kobman, operations manager, Merrill Fabricators. “It’s a big part of what we do. We want to give them the value-added services, higher reliability, higher quality, and repeatability.”
A good example is the touchscreen CNC (see Figure 2). While the operators needed some time to get used to the control after two weeks of training, they are not using it as an excuse for inaccurate parts. In fact, Kobman said rework has decreased dramatically because operators can more consistently meet the quality specifications on the first bend.
Accurpress’ six-axis Titan backgauge plays an important role in delivering repeatable bends (see Figure 3) and can work with large fabrications. Each X axis has a 65,000-lb. static load capacity and a 20,000-lb. dynamic load capacity.
“The machine learns what they are doing, and it records it. Then they can play it back,” Kobman said.
That’s especially good news for Merrill as it works with more specialty material like that armor plating. Scrapping a piece of metal worth thousands of dollars before it’s bent is not something that helps out the company’s bottom line.
The press brake has an automated crown adjustment feature. No matter the length of the part being bent, the press brake operator can feel confident that the ram will deliver exact pressure along the entire length because of the adjustment feature.
It also has a full 2-in. tilt capability from one side of the press to the other. If a blank with varying thickness is placed in the bed, the operator can adjust the ram within that 2-in. range to ensure a consistent hit when forming commences.
It’s not related to the controls, but press brake operators are very excited about the horn design at the end of the press brake, the horn that allows them to perform the bump forming that represents a nice chunk of the press brake’s scheduled jobs (see Figure 4). The feature allows them to bump-form up to 2-in.-thick plate, 2 ft. wide, and 30 ft. in diameter.
The press brake also has been prepared for some possible future enhancements. A foundation has been roughed in at the top of the press brake to accommodate a jib crane. One day, if Merrill wants to start bump forming rings of very large widths and diameters, it can install the jib crane easily to assist with the material movement during forming. Merrill also can add holders and automated material feeders to the front of the press brake if needed.
While Merrill has made strides in decreasing rejects with the new press brake (see Figure 5), it is still missing an important quality tool—its new bend angle measurement system, which will be attached to the backgauge. The bend angle measurement system acts as another quality check during the bend proc-ess. After a piece of metal is struck just short of where it’s supposed to be bent, the ram retracts slightly to let the material relax, and the backgauge moves over to measure the angle with its laser. The control takes the information and makes compensations for the second hit. The ram comes down and delivers the appropriate bend angle.
This type of technology is more common on smaller press brakes, but Accurpress engineers are in the finishing stages of making it work for the bigger units as well, according to Betts.
Gathering Around the Bend
With all the internal bending jobs now being done on the new high-tonnage press brake and five operators fully trained, Merrill is now turning its attention to attracting new business for the equipment. Yackel said it’s a perfect accompaniment to the very large fabrications it already produces (see Figure 6) and sees any service center or fabricating operation without big bending capability as a potential customer.
Meanwhile, Yackel is still hearing it from the current customer base.
“We have some companies that want us to go bigger,” he said. Merrill Fabricators plans on 2012 being a record year in terms of revenue. The company recognizes that where there are big fabrications, there are big fabricating opportunities.
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.