by Tony Marzullo and Bob Mathien
Take better control of your bending process
Are your parts less accurate? Tolerances slipping? Spending considerable time shimming your press brake? Taking 30 minutes or more to set up a job?
A number of variables go into achieving the desired part configuration–from tooling style to material variation to operator skill–but the more control you have of your bending process, the more competitive you can be. Retrofitting your press brake with a new control or backgauge may offer a short-term solution, but in the long run it’s a package of tools and technology that will help maintain accuracy consistently. For better bending accuracy, here’s what to look for:
1.Machine configuration
It’s not all about machine tonnage. It’s also about what machine length is best for the parts you’re fabricating. Years ago, a part with different segment lengths and bend angles meant several handlings and any number of tool setups. Today, single part handling is possible.
Define the overall machine length required. What’s the machine’s usable environment? The distance between side frames that’s useable for backgauge positioning? What’s the open space? A larger usable environment and greater open space provide capacity for larger parts and a range of part profiles.
Consider the function, flexibility, design and construction of the backgauge. The proper backgauge can resolve any number of accuracy limitations.
Consider a CNC crowning system if shimming is constant. Look for a system with rigidity to compensate for ram and bed deflection and use over the entire machine length.
2.CNC control
The modern press brake control does automatically what the machine operator of old would do manually to ensure part quality.
Touch screen is the leading control technology. Its icon-driven graphical user interface is comfortable for operators of any skill level.
Look for a control that has the intelligence or variance database built in. Databases composed of empirically-derived data are more accurate than databases composed of theoretical data. Bending parameters are automatically controlled by such a database, which stores and cross-references previous bending data experience with specific tools and materials. Modern controls have 2D and 3D simulation of the bending sequence to assist with part positioning. These elements make developing new jobs easier and faster.
Is the control layout friendly? More icons don’t necessarily equate to more capability or better performance. Check the control positioning. Is it readily accessible but located where it won’t interfere with bending?
Does the system account for varying user levels? Are there different modes for operators, programmers, technicians?
Also, does it come integrated with operation and maintenance manuals? Offer detailed part drawings to eliminate paper documentation? Provide a choice of languages? Offer remote diagnostic monitoring?
3.Offline programming software
Software goes hand-in-hand with the control and is another tool to help shore up the loss of in-house expertise. An integrated control and software package will help achieve consistently accurate bends.
Is the software developed and supported by the machine manufacturer or by a third party? This is an important distinction. Third party support may not be able to offer immediate accessibility to new features/functions.
Look for software that has the depth to provide growth or support for other aspects of your manufacturing. Think shop management and Industry 4.0.
4.Tooling
There is no way to ensure bending accuracy without the right tooling. The best way to select tooling is to work with the equipment and tooling manufacturers.
Can the machine manufacturer provide part evaluation via software for confirmation of machine and tool selection?
Tooling design will continue to evolve. Take the time to learn and understand the changes in tooling and how they impact your application.
5.Real time angle measurement
An in-process angle monitoring system adapts the ram position in real time to achieve an accurate bend.
A true “real time” angle measurement system provides feedback to the machine control for positioning of the ram to produce an accurate bend without secondary compensation. Systems that don’t operate in real time take a measurement of the angle at a ram position above the calculated position. From this, the system calculates the final position to create the accurate bend angle. This significantly slows the cycle time and offers little advantage over traditional trial and error bending.
Is the system flexible for use over the full length of the machine? Can one measuring device check more than one position or are several units required? The answers are critical to system efficiency and cost.
What criteria is required to operate the system? If tooling is specific to the machine manufacturer, learn what’s unique about the tools and how this impacts overall investment.
6.Air bending
Few applications still demand bottom bending. Today’s technology provides superior control of the bending environment in support of air bending. Air bending offers the advantage of requiring fewer tools. It’s best suited for precision ground tooling. While you’ll need less tooling when air bending, you will be paying more for precision ground tooling. However, total tooling cost can be less, and better tool steel and overall load capacity can help you apply this tooling to a wider range of material thicknesses and use the tools over a long life span. SMT
Tony Marzullo, manager of press brake product development, and Bob Mathien, manager of press brake applications
at LVD Strippit.
