The Fabricator - July 2010

Figure 1 The level of bending automation you need depends on myriad factors, such as part size and expected volume. In this setup, an automated blanking and panel bending cell speeds the fabrication of large panels.

Discovering the best

More recently bending technology has undergone a similar evolution, but admittedly, the challenges have been more complex. The modern press brake is now a CNC machine capable of high repeatability, but it still requires an operator to hold the part during the process and set up the tooling. A multiaxis robot can be integrated with the CNC brake to eliminate operator handling, but currently it does not efficiently address the tooling setup from one part to the next.

The panel bender changes this. The bending process can be fully automated—automatic tool setup, automatic part loading, complete part manipulation, and unloading (see Figure 1). It produces positive and negative bends quickly and accurately, no blank flipping required. The part stays flat on the machine table as only the flange is bent. Now, like the blanking machine, the bending machine controls part quality and, on some parts, forms in seconds what would take a press brake a few minutes.

Note the key phrase, though: some parts. Panel benders can’t handle everything a stand-alone or robotized press brake can, but then again it can do many profiles that are either very difficult or impossible to do in a press brake. In fact, bending automation has always been more complex. Aside from using punch form tools, blanking deals mainly with just two dimensions. In bending, you have all three to worry about.

Choosing which bending technology is best involves balancing maximum throughput with your expected return on investment. To uncover that, you need to have a good understanding of the bending requirements specific to your application and know exactly how your bending operators spend their day; that is, how much time they spend bending versus not bending. You need to know the setup times your parts require; downtime between jobs; the percentage of time operators are handling the part; your scrap rate, including scrap produced during setup (tryout parts) and rejected pieces produced during the run; and your average daily output of each machine. You need to know your expected part volume and optimal batch size that minimizes the cost of work-in-process (WIP). You also need to keep an open mind to all the bending options out there—and there are many.

path to better bending
Analyze the options, from the stand-alone press brake
to the fully automated panel bender
By Michael Stock
Technology Basics

hink about the old days for a second. A single-station duplicator punch press was the epitome of blanking precision for many a contract fabricator. Then this new technology called a turret punch press came along. It could hold multiple tools, move the sheet to the right location, and cut interior holes and part profiles. Production went through the roof. Then the laser cutting machine emerged on the scene and removed tooling and the associated setup from the equation, increased part profiling and sheet nesting flexibility, and yielded higher machine efficiency and maximum throughput in high-mix, low-volume applications.

However, more important than that, for the first time the machine controlled part quality. As long as it had the right program and the correct punch tools or laser focusing head, a blanking machine could read and execute programmed instructions correctly from the first part onward. If another batch of those parts came in a week, a month, even a year hence, the machine could produce the exact same part.

To be sure, skilled personnel are still needed to program, set up, and maintain the machine, and periodic edge quality inspection is still as important as ever. But when it comes to process operation, a human no longer needs to monitor a machine continuously to ensure it makes good parts.