Long-folding machines (typically from 13- to 40-ft. in length) have hit the American architectural sheet metal marketplace. First developed in Europe more than 25 years ago, and reaching the continental U.S. in the last decade, the long folder is fast becoming a mainstay of sheet metal-supply companies, metal-roofing companies and architectural-metal suppliers and manufacturers alike.

Many reasons are leading to the switch to long-folding machines over more traditional sheet metal machines such as roll-formers, press brakes, hand and apron brakes and even the old squaring shear. Flexibility to serve low lot sizes, improved aesthetics by reducing seams via longer parts, the ability to rapidly service immediate customer needs, replace last-minute parts damaged in shipment or short on an order, or even the ability to produce complicated shapes unknown before without tooling lead times and added costs.

Some long-folding machines offer operator-oriented graphics displays. Photo courtesy of EuroPress Metalforming Technologies Inc.

No tooling changes

The long folder requires no tooling to change. The specially engineered, precision machined "nose" of the upper clamping beam is essentially the only tool needed for the life of the machine. The material is formed around this nose with the bending beam, which allows the part to "breath," and to be properly formed without stress to part or machine.

In comparison, press brakes require frequent tool changes. Even in light-gauge material, an acute form can be easily made, but since most parts require hemming as well, a long-folder's clamping beam also performs the hem-closing function, whether open or closed hem, without the exchanging of dies and having to batch parts common to standard brakes.

From a safety viewpoint, on a down-acting press brake, the material is formed while both legs of the parts are moving. The long-folder generally has the most of the material laying flat inside the machine, and is only forming that portion of the part that is required. The part itself is not flapping up and down with the operator having to always catch the part. Also, because the material is well supported inside the long-folder, sheet support for flimsy material is generally not an issue; sometimes sheet support with regards to a press brake can be "Rube Goldberg" at best.

Shapes to be produced can be created away from the sheet metal shop and then downloaded to the machine. Frequently used shapes can be selected from a database. Photo courtesy of EuroPress Metalforming Technologies Inc.

Economics is key

When contrasting long-forming equipment to roll-forming equipment, it really comes down to economics. Roll-formers are well suited for longer production runs and have significant tooling costs and related lead times for such tooling. A general rule of thumb is approximately 75,000 to 100,000 or more lineal feet of the exact same part shape configuration per year would justify the roll-form tooling, and with enough parts, the cost of the machine itself.

Controls are the key to unlocking long-folder success. With the latest advancements in control technology, even the most complicated shapes can be tamed and produced accurately and repeatedly.

PC-based controls use the power of Windows software and allow flexibility for truly operator-oriented graphics displays. Trouble-shooting a tricky part for a long-folder can be done more rapidly when the operator can visualize the part being formed and perfect the process without ever having to bend metal - in fact, controls have become so advanced that programming shapes in the sheet metal shop can be done in the office an downloaded to the machine (or "sneakernet" via floppy disk).

Modern controls include touch-screen operation so the part is easily selected from a library of similar shapes and modified for the task at hand easily. Select the part, select the leg or angle that needs to be changed, enter a new value and in seconds an operator can be producing the new part configuration.

Flexible features

Features include the flexibility to tell the operator when to flip and/or turn the part, easily change the bed sequence, material library with spring-back automatically calculated for different materials or thickness, even informing the operator the proper flat blank dimension to make the part. The latest controls even offer the flexibility to "bump" parts for complex radius work as well.

In conjunction with an accurate back gauge, the CNC control has replaced much of the "lost art" of sheet metal bending and the years of experience associated with determining the best attack for a new profile. This makes finding operators easier and less expensive, especially when the learning curve is reduced to weeks instead of years. Other features include multiple-language displays, removing yet another barrier to finding help; the ability to form the part on the screen first (simulate the bending sequence before ever putting metal into the machine) and the unique ability of a PC to upload the latest software revision available for the machine to take advantage of the latest features and advances.

Another great feature available on modern folding machines is the machine-mounted rotary trimming shear. Though many companies have blanking lines, slitting lines or combination lines that can spit out finished blanks for forming rapidly and very efficiently, the trimming cutter mounted to the long-folder itself adds even greater flexibility for efficient operations.

A customer will often walks into a shop and want only a couple of bent pieces to replace damaged parts or a finish up work on a job site that was short a couple of parts. Murphy's law dictates that you will often have the wrong color, material or thickness on your cutting line.

Simple solutions

in a width that accommodates most trim shapes, and store them for every thickness and color, that way when someone walks up and wants something quickly, you won't have the setup to break and redo on your slitter or cutting line, just grab the appropriate blank off the shelf and make a customer happy - the slight scrap made by trimming with the long-folder will pay huge dividends in customer satisfaction.

In addition, the folder-mounted trimming shear may also eliminate the need for a squaring shear for the above scenario. If you don't stock pre-cut blanks, you will still have to drag out the appropriate material and batch process the right sized blanks - not as much trouble as on the combination line, but still one more step to the process.

When selecting a long-forming machine, look for the following features:

  • An operator-friendly control that minimizes changeover.

  • A rigid tension arm and stand assembly that will not crack, bend or twist such as that using nodular cast iron.

  • Hydraulic cylinders mounted on every stand to uniformly spread the load of the bending beam (after all, it's the bending beam that accurately "wraps" the part around the nose of the clamping beam) over the entire length of the bending beam, minimizing deflection.

  • Bending angle: more is better. The bending angle can never be fully achieved due to the limits of physics; there is spring back and clearances to be reckoned with. Look for a folder with 145 degrees of bending angle.

  • With respect to back gauges, simpler is better. Look for fingers that can easily be moved anywhere along the length of machine and as many added as needed.

    c The bending beam linkage is the key to uniform bending. The linkage moved by the hydraulic cylinders must be of a smooth working design; look for maintenance-free bushings between the linkages and the pins they pivot on. If these are steel on steel, they can wear, inducing error, and be costly to replace.

  • Bending beam vs. clamping beam mounted slitters: The bending beam is where all the precision is at - burdening the bending beam with the weight of the trimming shear and its associated track mounting only introduces error; by contrast, mounting the trimming shear on the clamping beam causes no part interference and the increased stability of the clamping beam is better able to handle the weight of this device.

  • Safety: Look for a safety device that can be triggered anywhere along the length of the machine such as a foot rail. If the worst would occur and the operator gets pinched, it's not always the force but rather the time pinched that can cause permanent damage. The sooner the operator in trouble can open the machine back up, the better off he or she is.

    Biegemaster BM

    New challenges

    New challenges in building design present new opportunities in forming. It's hard to know what's in the minds of architects; many never had to form a part their lives and many have no grasp for the manufacturing challenges of the new "look." An architect is challenged to catch peoples' eyes, not figure out how to make the sheet metal happen.

    New developments include "double" benders that can eliminate the need for flipping parts. Sometimes the trick in bending is figuring out which bends to perform first so there enough stiffness in the long part to be able to flip or rotate the part for the next bend without damaging it. Though the early efforts in these new machines is extremely exciting, the technology associated with this advance to date has been capital equipment cost-prohibitive for many smaller companies.

    Further developments will take the mystery out of making complicated shapes. Software revisions will continue until literally anyone off the street can tend and program these machines with the same results as the old pros.

    (Mike Weller is president of EuroPress Metalforming Technologies Inc.)