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Why automate your press brakes?

The answers help steer improvement in forming

A robot designed specifically for bending reaches behind the tooling to form a small, complex part.

Automating the blanking operation, including laser cutting and punching, is a big move for any metal fabricator, but it’s also somewhat straightforward, focusing on flat sheet and flat parts. Of course, there’s nothing flat about bending, and this makes automation much more complex and challenging. Nevertheless, current technology is overcoming most of these hurdles, and as a result, it has brought the benefits of forming automation to a variety of manufacturers.

Today’s automated bending systems can be configured to meet a manufacturer’s needs, employing different technologies to best match an application’s run size and part shape. The initial cost for these systems can be quite high compared to a stand-alone press brake, so the return on investment can be much quicker if the system is run over multiple shifts.

Still, before diving into bending automation, consider the big picture. The first step in the justification process is to ask one important question: Why do we want to automate?

I Need More Productivity

Historically, implementing a robotic bending system meant you needed to integrate a standard robot arm to an existing stand-alone press brake. Using the manual control pendant, you carefully taught the robot arm each and every move required to bend the part. Quite often you ended up with hundreds if not thousands of movements to create just one part program. Setups could take an entire day or even more, which meant that you needed lengthy runs for the system to be truly productive.

Today offline bend programming and simulation have changed the situation (see Figure 1). The programming software for stand-alone machines has carried over to bending automation, selecting tools and creating the setup, bend program, and robot program. This means that the operator need perform only a little fine-tuning before the job runs on the floor for the first time.

I Need to Reduce Labor Content

Reducing labor content goes hand in hand with increased productivity. Even when using a simple system of just a robot and a press brake, you’ll see a substantial reduction in labor input. After all, once setup is complete, the operation runs unattended.

Even if you have offline programming, though, you still can have a substantial amount of manual setup between jobs. You’ll need to remove and reinstall tools and robot grippers and load blanks for the next run. While all this doesn’t take nearly as long as using a manual pendant to teach a robot a bend program, all this work still can make it difficult to justify a system for the short runs found in a typical job shop. In fact, shops running lot sizes of 20 or fewer will find it takes more time to set up the job than to run it.

The reality is that, in most high-product-mix situations, any automated system requiring a person to intervene between jobs won’t give you significant reductions in labor input. Current systems, however, meet this challenge with advancements in automatic tool changing, robot gripper management, and software-managed scheduling.

Automated tool changing in robotic bending cells can occur in several ways. One is to equip the backgauging system with a tool-changing gripper that can pick and place tools into the press brake toolholders. Alternatively, the bending robot itself can be equipped with a gripper that can insert and remove tooling from the press brake bed, one tool at a time.

Still another way involves a dedicated, automatic tool-change rack. Suited for longer beds, these units slide entire racks of tooling into place at one time (see Figure 2). They also can rapidly move individual tool segments into the machine. Even complex tool changeovers typically take less than a few minutes to complete.

Figure 1
Offline programming software selects the tools and creates the setup, bend program, and robot program.

These systems often require tools designed to work with the tool-change automation. Still, fully automating the changeover can allow robotic systems to run entire shifts of short-run jobs without manual intervention.

Combine this with scheduling software and you create a bending cell, a fully automated option that covers all aspects of changeover between jobs (see Figure 3). When one job is complete, scheduling software in the control advances to the next job in the queue. The automatic tool-changing function sets the new tools, and the gripper changer swaps hands as necessary on the robot. The system then begins running the next job unattended.

Consider the application shown in Figure 4 involving a four-part kit. On a stand-alone machine, the operator has to program, set up, and run parts. The automated bending cell requires an operator to spend just 30 minutes at the beginning of the shift to create the schedule and load blanks for the day. The system then runs unattended for the rest of the shift, without breaks, requiring only periodic removal of finished parts. The result: Labor input drops by 90 percent.

The key to this application is that the technology automates everything that occurs between jobs, which can be so important in high-mix, low-volume production. True, a robot can run all day without breaks, but that alone wouldn’t have produced such a dramatic reduction in labor input.

I Need Tighter Process Control

When operators handle a part during the bending stroke, they may follow inconsistently, too quickly, or too slowly, and this can affect the final bend angle. Conversely, the bending robot follows the part at the exact speed and distance every time, so by its nature, automated bending yields extremely consistent bends.

Of course, no matter how consistent the bending cycle is, angles still can vary simply because the material hardness or thickness varies. In these cases, automatic angle measurement and correction can help. These bending control devices can measure the bend angle and, integrated with the bending robot movement, adjust the program on-the-fly to produce the bend angle within very tight tolerances.

I Need to Bend Small or Large Parts

Fabricators have turned to robotic bending to handle large, heavy parts for years. Performed manually, these applications typically require several operators to lift and manipulate workpieces. In these cases, a large-capacity press brake with a heavy-payload-capacity robot can form these parts easily and safely (see Figure 5).

This effectively doubles the labor savings and increases output, because these large systems can form heavy parts faster than multiple operators could working in front of a stand-alone brake.

Safety concerns also arise when bending small parts on a stand-alone brake. Operators may not break their backs lifting and manipulating small parts, but they do need to put their hands very close to the tool zone, which can be unsafe. Moreover, the short flange lengths on small parts can be difficult to gauge in a stable manner.

Today automated systems have robots designed specifically for bending. Coupled with press brakes that have large open heights, the robots can reach in and around the tool zone to form small parts safely and accurately (see lead photo).

Figure 2
Along with moving individual tool segments, automatic tool-change units can slide entire racks of tooling into place at one time.

Choosing the Right System

Bending automation has become popular in recent years, and with that popularity have come more options than ever. Those options have changed how fabricators think about streamlining their operations.

Automatic tool change on a stand-alone brake works for many parts that just aren’t conducive to robotic bending. Should a shop’s part mix change, however, these brakes typically can be upgraded to become a fully automated bending cell.

Robotic bending systems without automatic tool or gripper changes still may be the best choice, especially for high-volume part runs. Such systems also can work well if your applications require special tool shapes, since automatic tool- change systems do have some limitations when it comes to the tool’s shape, size, and weight.

For most shops operating in the high-mix, low-volume environment, the fully automated bending cell may be the right choice. Able to run a schedule of jobs while fully automating the changeovers, these systems yield the greatest payback in labor reduction and increased throughput.

This fact shows just how much robotic bending systems have changed. Until recently a fabricator wouldn’t have bothered to automate a bending job without sufficient volume of a specific part to justify it. And in some low-product-mix operations, this rule still holds true.

But again, current technology now can automate everything that occurs between jobs. This fact has opened the automation door for the high-product-mix application, be it a broad product family at an OEM or a diverse product mix at a job shop or contract fabricator.

About the Author

Scott Ottens

Product Manager

180 Amada Court

Schaumburg , IL 60173

800-451-3997