Bending Better

Many new press brake tools are ground to tolerances advertised in the 10-thousandths of an inch, introducing zero error to the bend.

Press brake tooling strategy plays a major role in reducing setup times while improving throughput in short-run bending operations. However, to get the most out of new developments such as staged tooling and simulation, fabricators must have the proper technology in place.

CIM—Canadian Industrial Machinery asked Paul LeTang, product manager for press brakes and tooling for Bystronic Inc., to describe how new technology in bending and tooling is affecting the way manufacturers process short runs. Here is what he had to say.

CIM: What challenges do fabricators face when bending short-run, high-mix parts?

LeTang: By far the No. 1 most important factor in producing short runs of high-mix parts is creating a “firstpart- good-part.”

The days of making extra tryout parts are vanishing. Fabricators now cut only the number of blanks they actually need. This puts so much extra pressure on the press brake operator that additional setup time is needed to double-check everything. This brings us to the second-most important factor in producing short runs of high-mix parts, which is setup time.

CIM: Should staged bending be used to reduce setup times?

LeTang: In many applications staged bending does address setup time. It is quicker to make one complicated tooling setup than to make three simple separate tooling setups, for example.

In the past the challenge has always been assessing the complicated setup by deciding what tools go where. Today many press brake manufacturers offer applications to make these staged tooling setup calculations in fractions of a second.

Once the operator begins the tooling setup process, placing some extra segments in the machine adds a negligible amount of setup time. However, staged bending requires a press brake with at least a 4-axis backgauge and active crowning system to deal with the varying staged bend locations. Multiple programmable foot pedals are nice to have too.

CIM: How can the labeling, storage, and maintenance of tooling affect setup time?

Press brake tooling strategy plays a major role in reducing setup times while improving throughput in short-run bending operations.

LeTang: On high-performance press brakes, about 90 percent of setup time is tool-changing time.

Because of this disproportion, anything that helps the operator with the tooling setups has huge payback. Optimizing tool changes by dedicating a complete tool library for each machine is getting very popular. This eliminates the time lost when the operator has to find the tools. Many press brake tool manufacturers now etch the tool identification information directly on the tool, and some tool suppliers even offer tool racks designed so that the operator can see all tools at once.

CIM: How does tooling strategy affect the ability to perform short runs of high-mix parts?

LeTang: Tool strategy affects three areas of performance: quality, setup time, and ergonomics.

The most obvious is quality. Tooling precision is directly proportional to part quality. Many new press brake tools are ground to tolerances advertised in the 10-thousandths of an inch, introducing zero error to the bend.

Tooling strategy also directly affects operator ergonomics and tool setup times. Both are affected by incorporating features like frontloading, self-seating, auto-centering, light weight, and easy-to-handle segmented tooling.

CIM: How important is offline programming when high-mix, lowvolume parts are produced?

LeTang: Offline programming not only improves machine utilization, it offers a “dress rehearsal” so that any problems are identified and addressed before the process is released for production. For example, virtual tools can even be tried out before they are purchased or modified. Ideally, the original part’s designers should have access to the offline programming so they can have immediate confirmation that the part designs can be formed with their current press brake and tool library.

CIM: How is new bending technology helping fabricators with their low-volume, high-mix parts?

LeTang: Almost all of the latest press brake technology is devoted to operator ergonomics.

The press brake operator is an integral part of the bending process. To address this fact, front-loading tool systems, work area lighting, touchscreen controls, voice-activated control, QR code readers, optical bend guiding systems, and self-adjusting safeguarding systems will all be commonplace on the press brake of the future.

CIM: Is simulation relevant for low-volume work?

LeTang: Part complexity has increased exponentially over the years. In order to reduce the number of components, many designers have combined multiple parts into one. Advanced CAD system drawing tools also contribute to part complexity.

When you couple more complexity with short runs of high-mix parts, the machine operator really has a challenge to understand the bending process. The simulation shows the operator, step by step, how to place the tools and the part. This feature not only saves time, it helps to ensure that parts are not formed backwards.

CIM: Are fabricators using automation in low-volume bending?

LeTang: Automation and short runs of high-mix parts are typically mutually exclusive on press brakes.

A press brake is a universal bending machine. Almost all press brake automation encroaches on the part shape envelope. Automation of short runs of high-mix parts has a sweet spot, and this means that the product’s life cycle has to cover the extra cost of automation.

CIM: What needs to be changed in tooling strategy when automation is used?

LeTang: Press brake tooling is more or less universal, so standard tooling shapes are often used on fully automated systems.

Some applications do require inprocess tool changes, however. In those cases, the tools are typically modified to adapt to the end effector of the tool manipulator. CNC clamping systems and front-loading punch holders are also machine features required for in-process tool changes.

www.bystronicusa.com