July 14, 2009
Today's folding technology can help bring a new level of efficiency and capability to a metal forming operation. Among the enhancements in modern folding systems are increased automation and gauging capabilities and the ability to fold an even wider range of materials.
Manufacturing process technology has grown by leaps and bounds over the last several years. Among the most noticeable innovations are those that help fabricators become leaner by eliminating the non-value-added components—asset consumption that does not directly add value to the part. This efficiency closely correlates with the necessity for fabricators to respond to price pressures, work with lower quantities, deal with labor shortages, and survive an economy clawing its way out of recession.
None of these business pressures are new. In fact, these same pressures drove fabricators to seek out a better blank or first ops process, which allowed lasers to overtake punching quickly and definitively as the blank production method of choice. The laser's process is independent of tooling, material, and blank geometry, making it an extremely flexible machine tool that requires little to no setup when changing from one part to another, even if doing so takes the process from ¼-in. mild steel to 18-ga. galvanneal.
Laser blanking is a perfect example of lean—the ability to cost-effectively produce a quantity of one. The operational savings are based on increased efficiencies, and not necessarily on how fast a particular part is profiled.
Technological advancements coupled with a changing environment enabled fabricators to position lasers where they are today. If lot sizes were still in the thousands, stamping would reign supreme, and if laser technology failed at aligning process capabilities with fabricators' needs and desires, turret punch presses would still be the dominant favorite.
Concurrent changes are again taking place, this time in metal bending technology. Press brakes have always been the dominant player when it comes to forming parts as they move through the fabrication process. However, as with lasers, current folding technology can make folding a good option for the challenges fabricators face today.
Nothing is worse than spending more time preparing to bend a part than it actually takes to bend it. This certainly is not lean! Tooling used in a folding system is universal and independent of material thickness. It is common for a folder to have only one set of tooling that can form the full range of materials a shop processes. No longer does the operator need to strip off the entire set of tools to switch from one material thickness to the next, or to adjust for inside bend radius. The only change required is to regap the openings to accept flanges on multiple-sided parts. With the tooling setups calculated and stored per program in the control, setup typically takes less than a minute. Hydraulic clamping tool systems make this no more complex than unclamping the tools and sliding them to their proper position.
With current folding technology, it gets even easier. Automatic tool changing (Figure 1) and tool gapping (Figure 2) systems completely eliminate operator involvement with tool change. Once a new program is created or recalled, the system automatically positions the tooling and the part is ready to run.
Automatic tool changing physically removes the tooling from the beam, which allows complete tooling layout reconfiguration; automatic tool gapping simply relocates gaps in 1-in. increments anywhere along the forming line. This type of system can make setups as quickly as it takes the operator to pull up the next program.
The inherent nature of folding eliminates the vast majority of error caused by material variation. If a part has been run in the past, it is common to be able to reload it, and run first part good part.
Rotational clamping beams (Figure 3) also can reduce setup time significantly. Imagine being able to form a part with 2-in. radius forms on the sides and sharp bends on the ends. With a rotational beam, this part can be formed in one handling and one setup, while allowing differing tool heights on each side, differing radii, and anything else the job requires.
Machine control system technology has likely had the biggest gains. Leading control technologies utilize PCs with enormous speed and processing power. Flash card internal memory has replaced hard drives and allows for inexpensive memory expansion, and as with any PC, networking is simple and secure.
Machines no longer require operator programming; the interface between human and machine is simplified to the task of drawing the part, and the control does the rest. Higher-end systems use virtual 3-D graphics to check for collisions, provide to the operator the bend sequence, auto-calculate the best setup strategy for tooling, apply correction calculations based on sophisticated material databases, and optimize machine functions for maximum throughput. This creates an optimal program, regardless of the operator's skill level. In short, the intelligence of the operation now resides in the control, which enables the operator to carry out a task quickly and with very little effort.
DXF file importation and offline programming provide an even faster conduit for operation. Once the jobs are set, remote links to scheduling systems relay the day's production requirements directly to the machine control. All the operator needs to do is execute the plan.
Remote service and support capabilities provide for direct linkage to the control system and the entire machine tool. Coupled with remote Webcams, a service tech can be on-site virtually within minutes for a machine problem, additional training, and any other support desired. Remote monitoring systems that automatically track the system's performance are widely available with the goal of fixing the machine before it goes down.
A core advantage of folding is in the way it gauges. The machine actually gauges the part, which is uniquely different from a press brake, which gauges the flange. The folded part is fully supported by the rear sheet support system (Figure 4) and stays horizontal during the forming process, so only the flange moves during the bend. As a result, the part is accurate dimensionally, because the finished form dimension is gauged and the part then is clamped in place during the bending cycle to ensure it is held accurately.
Ergonomically unwieldy parts often require multiple operators on a press brake, which slows the forming speed. These parts often can be produced with a single operator on a folder.
Safety is a big concern when handling parts. A part that never leaves the horizontal plane is safe, because whip-up is completely eliminated, as is its close relative, backbend.
The disadvantage to the way a folder gauges is that in order to gauge a bend line, it needs a parallel edge to gauge against. Until recently this requirement made it impossible to fold parts that do not fit the folder's gauging capabilities. CNC frontgauging (Figure 5) has eliminated this restriction and can now provide gauging for any formed part. Nonparallel bend lines, tapered flanges, and odd perimeter shapes with flanges on all sides now can be gauged and formed easily while still benefiting from the sheet support system and horizontal part holding.
Nothing adds more cost and destroys efficiency quicker than having to flip a part in the middle of the bend sequence. This process is even more costly if it requires more than one operator. It is dangerous, can damage the part, complicates the operation, and adds no value—only cost. It is interesting to note that with every flip of a part, the operation gives up two to five bends. During the course of a day, this inefficiency stacks up to considerable product volume being lost at the expense of non-value-added material handling. This loss alone might justify the additional cost of a bidirectional system (Figure 6).
Bidirectional forming has been available for some time on thinner gauges, and the process is well-suited to large production runs of panel-type parts in an automated format. Forming in both directions is no longer limited to thin gauges. Bidirectional systems capable of forming up to 3/8-in.-thick plate are available, and ½-in. systems are right around the corner. These systems are available on a stand-alone platform that allows for operation from the front of the system in a monodirectional mode, or from the back in a bidirectional mode. This makes bidirectional folding an ideal process for short-run products,or parts too large to fit the traditional panel bender. Rotational beams, automatic tool changing, and automatic gapping all are available on bidirectional systems.
Many parts suited to folding can be gripped by the backgauge (Figure 7), which can serve as a feeding device to move the part through the forming cycle. Buckets for the skid steer industry are a perfect example. The blank is fed into the folder and gripped by the gauge system, which automatically feeds the part through the forming process. The operator then engages the part, removes it from the system, and loads the next blank. This process is well-suited for a simple pick-and-place robotic system, creating a fully automated forming cell.
Sheet metal parts can benefit from the same type of processing, and with a grip system holding the part securely in a fixed gauge point, the datum is kept consistent. Grippers can be configured to grip either the back edge of a part or around a side flange for multiple-sided parts. Since the operator is not engaged with the forming process, multiple parts can be loaded at one time and formed together. This increases output and reduces costs even further. Note that some of these systems do require some additional setup time, which makes them better-suited to larger lot sizes.
Automated folding systems (Figure 8, see image at top of page), often referred to as panel benders, have been around for some time. They typically incorporate both material handling and automatic tool changing. Panel benders sometimes use a wiping motion instead of a folding motion for additional forming speed, allowing for greater efficiency in producing various parts.
As stated previously, automated folding systems typically are recommended for larger production runs of panel-type products. However, advancements have completely changed the capabilities of these systems, which now can accommodate thicknesses up to 0.196 in. and blank sizes up to 5 ft. by 10 ft. Increased open heights up to 26 in. allow for parts with depths up to 13 in.
The folding process allows for complete control of the inside bend radius, and many of the described enhancements are available on panel benders. Although panel benders are fairly expensive, their increased part envelope, thickness capability, and part depth allow for forming many different products. With these machines, you can produce many parts consistently with minimal setup. The only challenge is having enough product to keep a panel bender running, because these automated folders have a huge appetite for parts.
To maintain a competitive edge, you must produce better, faster, and at lower prices. To meet these challenges, you need to examine all possibilities without prejudice to process. In the end, it really does not matter how a part is formed, as long as it has been formed using a process that allows for the elimination of all non-value-added costs.
The goal is to look for parts that can take advantage of a folder's efficiencies and flexibilities, and apply folding technology along with your current forming capabilities, bringing a new level of efficiency and capability to your forming department.
Through competent planning and decisive maneuvers, you can become better prepared to take advantage of newly developed technologies to overcome the challenges of today, and position your company to tackle the challenges of tomorrow.