Press Brake Tooling Design Evolves
Not very long ago, press brake tooling was called planer ground tooling, or planed tooling. It was milled from long lengths (sometimes 10 to 14 feet) of tool steel blanks. When a job called for a specific length, someone would cut the tooling to match the part measurement. However, the precision was never such that you could reliably have any two punches or dies next to each other and expect all to go well. Modularity wasn’t an option if you needed to be precise too.
For the last 10 to 20 years, fabricators have relied on modular precision ground tooling. It’s the type of tooling you see today in many press brakes. Modular precision ground punches and dies come in a variety of types and lengths, and can be combined in any fashion as long as they are the same type and they add up to the right length.
In Figure 1, we see a good example of how the modular precision ground tooling is combined in the press brake. The first station shows a single punch and a single die. The second station not only combines the lengths but reverses the type as well. The third station echoes the first, with a one-to-one match, and the final station has a single die but six punches in varying lengths.
Variety and low counts require new methods
While the old way might have done the job for fabricators who made many of the same part every single day, it would not do well in today’s high-changeover environment. Today, instead of purchasing a single length of tooling, fabricators buy punches and dies in the following lengths:
- 835mm (long)
- 510mm (short)
- 200mm
- Sectionalized pieces adding up to 370 mm, from 100 mm down to 10 mm
An ear set of 100 mm punches is also available.
Using a variety of lengths, fabricators can bend just about any part they encounter, and accurately. The problem with the old method is that sometimes an odd size came along and a common size punch and die would have to be “sacrificed” to do the job. With modular tooling, it’s the same inventory every day—and an inventory that is easy to track because it is a limited, discrete quantity of tooling.
Assisted by the modular nature of today’s tooling, AMADA’s offline software and control software can create tool setups and bending programs for the operator. This is especially helpful when the operator wants to create staged bending in which a part is put through multiple bends in a sequence on the same press brake. Software helps tremendously when it comes to tracking these complex setups and frees the operator to do the bending accurately and efficiently. In today’s short-run environment, the software is valuable in reducing time between many different jobs.
How to achieve accuracy in tooling
Each AMADA punch and die is hardened and is ground in a CNC grinding machine to achieve tolerances of 0.0008” or 0.02mm. Figure 2 (left) shows a grinding machine in mid-job working on a long (835mm) punch.
As long as the precision requirements are met, this punch will work with all tools of its type and shape.
Figure 3 shows the 835mm punch being ground in a custom setup that accommodates the shape of the shoulder and allows for equal pressure across the length of the punch—almost 33 inches’ worth. The grinding wheel has a V-notch that is dressed before grinding. We get a very good cross-sectional look at both the punch and the grinding wheel in Figure 4. Note also the specific insert that holds the punch firmly in place at the shoulder; preventing movement is paramount in achieving the necessary precision. A different insert would be used for a differently shaped shoulder.
Time to punch in with AFH
While modularity was a clear advantage in press brake tooling, there were still potential hurdles to overcome. For example, the height of punches varied widely, often according to its function or even its shape. While at first height difference doesn’t seem to be much of a disadvantage, clearly there are two areas where it is not a definitive solution:
- In situations where staged bends would save time, conventional tooling may disallow it; and
- Laser safety devices on a press brake must be set to different height levels when using tools of different heights.
To decrease setup times and increase flexibility, the company offers AMADA Fixed Height (AFH) tooling. AFH punches are consistently 120mm in height and the dies have a common pass height of 60mm. Measurement for the punch is from the top of the shoulder to the bottom of the tool; measurements for the die are from the bottom to the overall top of the die (at the edge, not at the bottom of the V). Because of this, different size V-dies cannot be staged next to each other in the same setup.
One other advantage from AFH tooling design is that it enables other technologies such as the Bi-S bend angle sensor, which is used to get the perfect bend angle from any bend. The Bi-S can be used on each bend in a short run, or deployed once to capture bend settings, which will be the basis of the remaining bends in the job. Figure 5 shows a setup using AFH punches with different shapes, as well as the Bi-S deployed from the two sides on the bottom to measure the bend angle with great accuracy and report it to the control software.
AFH tooling brings speed gains. Because of its design and consistency in manufacturing, fabricators can easily do stage bending. It also makes programming a little easier because you have a common pass height for every bend; you don’t have to enter different heights for each tool.
Further evolution from the bottom up
The design of AFH punches brings obvious advantages—but the story does not end there. What if instead of a common pass height there was a common shut height, i.e. measure from the bottom of the V rather than measure from the top of the die itself?
Not only is it possible, it’s available—in the form of Common Shut Height dies from AMADA. For reasons easy to understand, these dies utilize only AFH punches. Using AFH punches and CSH dies, multiple styles of punches and die V-sizes can be used in one tooling setup. Figure 6 shows the idea behind CSH, and shows some of the punch/die options fabricators can use.
A variety of bends—V, radius, offset, flattening, and acute—can be combined in a single tool setup, and can be the missing equipment that brings fabricators to uncommon thickness kit nesting or making parts that include any combination of forming types.
As the market increases its demand for more exacting tolerances in forming products, fabricators need to enter these higher-margin markets armed with more precise tooling. It just so happens that the same tooling that is more precise than ever is also the most flexible on the market. The time savings of multiple setups using AFH punches and CSH is easy to demonstrate. The tangible result is higher productivity with more precision—an impossible pair of goals only a few years ago.
