Press brakes are more efficient than ever. Featuring both software and hardware advancements, today's machines allow shops to process parts faster and with greater precision. Modern press brakes can easily be linked to other automated equipment and to computer networks. Their software capabilities also optimize the process, allowing shop employees to ascertain the best tool for the job and to compensate for part variation. Shops investing in these machines can expect short-term and long-term benefits.

Shops can enjoy dramatic productivity boosts by employing press brakes designed for robotic loading. Illinois-based Finn-Power Intl. Inc., press brake manufacturer, recalls one purchaser's experience. "The shop was able to increase production by 50% and save labor costs," says Finn-Power vice president Patrick Canning. Production rate rose from 200 to 300 parts per shift. In addition, the press brake's robot freed the two operators who previously had to carry large, unwieldy panels during each shift. Eliminating human intervention meant greater part quality as well, says Canning.

Press brakes are more versatile because of robotic enhancements. For example, Finn-Power's design, which works with a standalone robot, can handle both small and large panels. By detaching the robot from the bed, Finn-Power design engineers created the space required by the manipulation of big panels. In addition, the extra room enabled the use of larger, sturdier robots that could lift up to 140-lb. loads. These standalone robots can complete multiple tasks, such as working simultaneously with two machines. With software controls, users can load different programs to direct the robots in various bending processes. "You don't have to bend 4,000 parts for robotics to be practical," says Canning. "You can do 25 parts and change to do a different 25. The flexibility is enormous."

Software enhancements are also allowing shops to deploy press brakes with greater deliberation and planning. Modern press brakes offer offline programming and simulation packages, which have made job estimation much more accurate. Using simulation, a shop can determine the necessary tools and setup to make a part. It can also figure out setup and processing times. With these software tools, programmers can plan jobs, optimizing results based on tools that are in inventory. Cincinnati Incorporated, Cincinnati, even offers a sophisticated tool library that builds the optimal tools by combining tool segments stored in inventory. "Our tool library has an auto-calculate function that helps a programmer determine the segment combinations available for building the tool," says Todd Kirchoff, press brake product manager. Finally, with increasingly advanced three-dimensional graphics on controllers, programmers can show operators exact tool locations on the bed and ram so setup is less time-consuming.

Software controls guard against part variation. Since the latest press brakes come with Ethernet cards that allow them to connect to other automated equipment and to computer networks, the entire company can share one database. Operators simply download programs from the central database, eliminating the possibility of operators using different program settings or tools. Furthermore, many press brakes feature angle-measuring systems, which let operators prevent discrepancies. For example, California-based Amada America Inc. offers a digital protractor with which users can calculate angles and correct disparities. Finally, software innovations have enabled the development of schemes to compensate for variations in material thickness. For example, some manufacturers use their press brake's upper and lower beams to measure thickness. The machine's controller then adjusts the program for any deviation from the planned thickness. Unfortunately, thickness compensation technology is still not practical for large lots. "If you're running small lots, however, it's great," says Nick Bach, Amada's press brake manager. "Even though it slows the operation slightly, you have more confidence the bend angle is going to be right the first time."

Press brakes are now capable of multi-axis control—in some cases directing as many as 10 axes. This has simplified setups as well as allowed the fine-tuning of bends. However, multi-axis control, which enables the sides of the ram to work independently of one another, has problems with off-center or asymmetrical bends. Press brake builders are addressing this shortcoming with software that determines an adjustment for each side of the ram based on material, tools and position on the bed. Meanwhile, crowning algorithms take care of the ram's center, where deflection occurs along the upper and lower beams. These algorithms automatically generate an appropriate crown in order to compensate. In machines such as Amada's, hydraulic cylinders in the center of the lower bed also allow users to make adjustments. Trumpf, meanwhile, employs a slightly different deflection compensation method. "Instead of pre-crowning the center of the machine, as most crowning systems do, this machine's bed relaxes on the ends, allowing the crowning at the ends of the machine to align with the center," says Lynn Moore, press brake product manager.

Recent press brake innovations also involve electric and hydraulic actuation. Trumpf, for instance, has come out with a line of two electric press brakes. These machines offer greater precision with 40-micron repeatability. They also promise shorter cycle times because of a rate of acceleration that outpaces that of hydraulic systems. Meanwhile, Amada has introduced a press brake with hybrid electro-hydraulic drives. This system, which uses servomotors to drive the pumps, runs at cooler temperatures than hydraulic machines. Oil temperature is more stable and causes less damage, lowering the drives' oil consumption. Moreover, the ram is able to position itself within 0.001 mm—a greatly improved order of magnitude. Another press brake improvement is hydraulic tool clamping. Although by no means a new feature, hydraulic tool clamps are becoming more common in press brakes because they allow operators to fasten tools within two seconds—compared to about five minutes using a wrench.

Shops should carefully consider whether the latest press brakes are right for them. A shop mass-producing one size of small channels would be better off with a dedicated tool with gages. On the other hand, a job shop producing channels of multiple sizes in small lots would benefit from the latest press brakes. "A shop bending a variety of parts and then changing tools to produce others doesn't want to be loosening bolts," says Steve Lazinsky, president of Maryland-based COMEQ Inc. He recommends that users thoroughly evaluate press brake options to ensure a good fit and an enhanced bottom line.

Source: Press Brakes: Bending the Rules for Better Parts
James R. Koelsch, Contributing Editor
Forming & Fabricating, May 2002
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