4 Tips You Should Know About Custom Press Brake Tooling

Estimated reading time: 10 minutes

Does your store need custom press brake tooling? The following four questions will help find the answer.

1. What Is Really Important?

In terms of press brake tooling, calling design engineers quickly can save a lot of money. Of course, some prints are what they look like; if they require specific angles and radii within specific tolerances, this is what they need, and the discussion is over. But this is certainly not typical. Such assumptions may make the parts much more expensive than needed.

Consider a print that requires 10 inches. The radius is formed to ±0.002 inches, and using modern bending machines and carefully crafted custom tools (after countless tests and rework), this tolerance may actually be possible. But is it really necessary? A quick call to an engineer may find that the large radius is purely for strength purposes; there is really no need to keep the radius within such tight tolerances (see Figure 1).

Offset is another prime example. Suppose the print will show the offset as two 90 degree bends and specify the height. Sometimes the offset height may not be the standard size, such as 0.250 inches, but 0.236 inches. Talking with the design engineer may find that, yes, the offset height of 0.236 inches is critical, but the 90-degree angle is not.

2. Can We Bend Parts With Standard Tools?

Once you understand the true manufacturing requirements, you can begin to evaluate the tools that can be used to complete the job in a competitive and safe manner. “Competition” and “safety” are the keywords here. Yes, you can let the brake operator flip the large part for the second bend of the offset without relying on a dedicated offset tool; or you may bend the narrow flange into a large panel and swing the large part to On his head. But both situations involve concerns about safety, quality, and efficiency.

This is where worker ergonomics enters the equation. The wiping and rotating tool allows the operator to insert the workpiece horizontally while the tool folds the edge flange up or down. The wiping action does require the tool to have a thrust plate to counteract the horizontal force during the bending cycle (see Figure 2).

The rotating tool uses a rotating cam with a V-shaped opening (the so-called Pac-Man tool) to fold the edge flange around the anvil punch (see Figure 3). Since the cam rotates throughout the bending cycle, the contact points leave very few traces on the outside of the bend.

Sometimes standard tool sizes are indeed a viable method. Consider again an offset application with a critical height of 0.236 inches but a non-critical bending angle. They are designated as 90 degrees, but they do not have to be exactly 90 degrees. In this case, you can use the standard 0.250 inches. The offset tool controls the height of the plunger to leave a 0.236-inch high offset, you should be happy, depending on what your bending angle tolerance is (see Figure 4).

3. How About A Die Tool Without A Punch?

Years ago, many fabs were stamping in-house but sent some jobs for laser cutting. Today, many manufacturers are doing the opposite. They have established fiber laser cutting capabilities but sold old punches. Then they saw that a printed matter needed a form that could be easily made with the forming tools on the press. Therefore, they eventually send the work to another workshop that has a punching machine equipped with the correct forming tools. Or they give up their work altogether, just because a molding operation makes the work unprofitable.

In other cases, the parts that can be most efficiently formed on the press sometimes have problems with working routes. A store may only have one punch related to large-scale operations. Unfortunately, another small job has several extrusion holes, but the punch has no direct production capacity. The lasers in this workshop have sufficient cutting capacity, but these lasers cannot form extrusion holes.

Punching dies have another advantage: price. Suppose you need to form a small blind. If you don’t have a punch press, traditionally your only option is to manufacture or order a shutter punch and die set for the bending machine (see Figure 5).

Unfortunately, even standard shutter punches and die sets are more expensive than punch die sets that can do the same thing (using less tool steel). The same applies to small hinges, flanges, spears, and forming clamps.

However, today, certain punch forming tools—especially certain Trumpf-style forming tools of size 2 and thick turrets (E station) and smaller—can be mounted on adapters and used on press brakes. For example, if you need to form a small shutter or relief, you only need to slide the blank between the shutter die toolsets; the edge of the blank hits the stop integrated into the tool and forming begins (see Figure 6).

In some ways, once the die tool is separated from the punch, it will actually become more powerful. No longer limited by the height of the punch stroke, the forming tools on the bending machine can create very high forming. For example, flange forming tools can form flanges that are much taller than typical presses.

Note that a bending machine is a forming machine, not a punching machine. The bending machine adapter can use punch forming tools and some chisel point tools, which can effectively punch one-eighth of the shear force (one-eighth of the thickness of the material) onto the surface of the material. However, the design of the device cannot withstand the punching stress and subsequent elastic penetration force.

For many years, manufacturers have used C-frame tools and other methods to punch holes in the bending machine, so it can be done. However, if you have a choice, try to perform the cutting operation on another machine (such as a laser). The blank reaches the bending department, and the cutting operation is completed; the improved stamping forming tool on the bending machine only performs forming. In this sense, the “punching tool” has been changed to a “forming tool”-the same as before, except that there is no punching. For example, the spray gun forming tool will not cut (again, the cutting has been done on the laser), it will only shape.

Custom forming tools—designed specifically for press brakes but processed from stamping tool stock—open up all kinds of possibilities. Consider a small part with multiple flanges, which is difficult or impossible for the operator to manipulate even with the smallest traditional brake tools. Custom molding tools can be made from round raw materials (so the price and delivery time are lower), mounted to the base adapter of the bending machine, and allow the brake to create complex components in a single stroke (see Figure 7).

When it comes to the limitations of using stamping forming tools on brakes, tonnage issues occasionally arise, especially when there are large embossments on thicker blanks, which will drive a large amount of forming a force to a small area. However, this tonnage problem is relatively rare. The main limitation concerns the size of the form. If the template requires more space than the space provided by the stamping tool, you cannot choose to use the template tool adapter for the bending machine.

4. What About 3D Printing?

3D printing provides more options for custom tools, especially when using composite materials and high-strength resin materials and printing methods to create tools with high dimensional accuracy. The rated tonnage of these tools is not enough to bend thick, high-strength plates, but they are becoming a viable option for a range of sheet metal applications.

For example, using printed V-shaped mold inserts can achieve specific part requirements or bend without scratches. 3D printing is also used to reduce costs or increase the flexibility of custom bending machine toolsets, especially toolsets that form multiple bends or parts at once (see Figure 8).

A single part may not be large enough to justify a complex custom tool, but a part series may. The operator may use a printing tool with a steel base; to form another part in the series, the operator only needs to replace the printing part of the tool with another variant.

3D printing has applications beyond the braking tool itself. Consider custom measurement. Some jobs can be formed in custom or even traditional toolsets, but measuring them correctly can be a burden. Operators may rely on pin stops or other settings, but getting them to work may require time-consuming process adjustments.

However, printed custom meters can change this situation. They can be as simple as a gauge screwed to the back of the tool body (see Figure 9). Or they can be as complex as custom-made side gauges, consisting of steel bars with a printed “sheath” whose contours fully conform to the part’s side gauge requirements. And, of course, the sheath can be replaced with other custom-printed sheaths, and the side gauges can be modified as needed.

3D printing can also help process parts. Consider again the stamping tool installed on the bending machine adapter. It may be able to quickly produce a small part, but the operator still needs to retrieve the small part. This may take time. The operator may lose some parts, and the parts themselves may be a bit sharp and dangerous to pick up.

To improve efficiency, you can print a chute and a small container next to the tool. The forming tool can be recycled, and then the formed part can be dropped from the chute and directly into a small box, after being filled, it will be taken to the next operation.

Find The Best Path

These four questions provide you with available options. Which one is meant for your operation depends on the usual doubts, including part requirements (required tonnage, radius, and angle accuracy), volume, demand consistency, and the combination of workshop technology.

If you have enough punching capabilities and a huge tool library, you may choose a path that is different from the path used in a workshop with multiple lasers and only a single-station punch. In any case, knowing all the options will help reveal the best path to success. Today, this path may include some elements—such as 3D printing and the use of press forming tools on bending machines—elements that were basically unheard of ten years ago.