Don’t waste time getting tools in the press brake

Nov 06, 2024

Electric clamping systems promise to deliver minimize maintenance requirements when compared to hydraulic systems.

Press brake setup has a way of meaning different things to different people.

For certain operators, setup was the time it took to put the punches and dies on the press brake. That seems pretty straightforward, but if the operator also was involved in trying to shim up an old brake so that crowning was minimized during the forming cycle, that time involved in getting that first part right might have been left out of the setup equation. After all, the tooling was set up and ready to go in 10 minutes, even if it might have taken a full 30 minutes to get the brake ready to form parts.

Today, press brake setup time is not as open to interpretation as it used to be. Process engineers have a focus on uptime, and anything that works against that is quickly labeled as waste. A 30-minute setup time isn’t going to cut it.

Fortunately, that’s not as common as it once was. Operators often don’t require the assistance of lift trucks to load up 10-ft. sections of tooling; sectionalized tooling can be loaded quickly, even if manual clamping is involved. An automatic crowning system gets an operator close to forming a part that meets specifications right from the start. Advanced control software provides visual clues as to where the tooling should be loaded and how the part should be bent, taking a lot of guesswork and trial and error out of the bending process. The time it takes to move the finished parts out of the workspace, move the new blanks to the workspace, actually remove tools, place them in the cabinet, retrieve the new tools, place new ones in the brake, and make a good part is now what many can agree comprises press brake setup time—last good part to next good part.

With that in mind, the focus on setup time is now measured in minutes. Like a NASCAR pit crew looking for the slightest improvement in a pit stop, continuous improvement teams are doing the same for the bending department. A few minutes saved during press brake setup compounded over multiple shifts and workdays translates into significant time savings over a year. That’s more uptime forming parts and more capacity open for additional work.

Clamping systems help metal fabricators to find that efficiency when changing over tooling for the next bending jobs.

Manual clamping is probably not so much a system, but a method of holding the tool.

Any press brake operator working with manual clamping will quickly become familiar with clamp plates and set screws. They also will learn the process of getting tools seated and ready for bending.

When tools are tightened manually, they are traditionally not seated without a secondary operation, which in many instances is a press brake cycle that puts pressure on the tools to seat them in place.

Brake operators need to be aware that uneven distribution of clamping pressure is a shortcoming of manual clamping. Clamp plates deflect around punch tangs, and set screws miss the punch tang if the set screws aren’t spaced properly. In both scenarios, the operator doesn’t have a good idea of what is clamped properly or if it is clamped at all.

Hydraulic clamping systems are an efficient style of clamping. They can be fitted on both old and new press brakes. In the cases of older press brakes, these clamping systems might be the best way to repair the problem of well-worn load bearing surfaces, while at the same time increasing clamping and setup efficiency. Images: Wilson Tool

These types of clamps do remain a popular choice because they have been around as long as press brakes have been made, and they offer the lowest cost clamping alternative when purchasing a machine. However, affordability doesn’t always equal efficiency.

In another note of caution, metal fabricators need to realize that some press brakes being sold in North America likely have holders made of soft steel and looser tolerances than you would see in a precision tool (+/- 0.0004 in.). If your press brake varies in tolerance, the inaccuracies, in this case holder size, will carry through to your part. Low-tolerance holders can make a relatively good press brake appear to not work very well.

With that being said, manual doesn’t always mean low tolerance or inefficiency. Some manual holders on the market demonstrate efficiency in changeovers and do not require a hand tool. In this modern manual clamping scenario, clamping and seating are initiated with the lifting action of a handle.

These holders tend to cost more, are precise, and are made out of hard tool steel. They can be segmented, which allows the operator to use the holder as an extension to the punch height. For example, an operator can load a 1.2-in.-tall punch into a 4.7-in.-tall holder, lift a handle to clamp and seat the tooling, and bend a box that has approximately 4-in. side flanges. If a solid beam is used to clamp, the operator would need to handle a roughly 6-in.-tall punch. If the conversation focuses on gooseneck-style tooling, that could be the difference of lots of weight.

So, if you can reduce tooling height by using segmented holders, you can purchase shorter tooling, which makes it easier for the operator to handle. The company and employee win in that situation.

Maintenance on a manual system is not complicated. If damage occurs, replace them. There is no oil to worry about.

It should be noted that some metal fabricators are perfectly content to use manual clamping systems for their press brake tooling. It might not be as quick as hydraulic or electric systems, but due to the mix in product and the nature of business, a company might not need more complex alternatives.

The emergence of hydraulic clamping systems changed the game for press brake operators. Instead of them taking time to find a hand tool, place tools into position, and then tighten separate clamping plates or set screws every 2 in., the hydraulic systems allow that same operator to clamp and seat all the punches with the press of a button.

Hydraulics also was part of the precision tooling movement worldwide. Shorter length tooling that could be handled by one operator, and tight tolerance make tool changes manageable by one person. There was no longer a need for a fork truck to move 10 ft. of low-tolerance tooling.

Tighter tolerances on precision tooling also meant sections match. When sections match, it reduces setup time because the press brake operator isn’t finding uneven bends over the length of the part—at least not because of the tooling. (We’ll leave conversation about deflection, machine repeatability, and material for another article.)

Remember, last good part to next good part is the window of time we are reducing. We now can, without looking for a hand tool, load a segmented punch with one operator and push a button, securing the tools and getting the brake ready to bend.

With modern hydraulic clamping systems, a light most likely will give you an indication that the holders are clamped or not clamped. This contributes to secure and fast clamping, alleviating a bit of stress for the operator.

The downside about hydraulic systems is that they are all one piece. They have to be one piece so the urethane bladder that is filling with fluid can expand and actuate pins that do the clamping.

This solid upper beam has encouraged the use of taller tooling. If you want to do a 4-in. box like in the previous example, you are now using 6-in.-tall punches every day in case you have a 4-in.-tall flange. This arrangement increases the common punch height and weight for precision tooling.

Although hydraulic systems are generally up and running with minimal maintenance, if damage occurs to the body or the urethane bladder develops a leak, the press brake will be nonproductive until a trained service technician arrives. A metal fabricator also can expect a hefty cost to replace the body of the holder or inner bladder. Downtime in production likely will exceed the cost of repair.

Maintenance requirements on hydraulic systems include visual inspections to make sure clamping pins are working properly and to look for leaks. Any system with moving parts most likely can fail, so it is important to regularly inspect moving parts.

Having considered all the risks, hydraulic clamping will improve changeover efficiency when compared to an operator that has to work with traditional set screws.

Electric clamping is coming. No, there’s no need for batteries. No, these clamping systems aren’t heavy or ride hard. No, they don’t look like a sheet metal shape they call a truck. They haven’t even been released to the market, but they are coming very soon.

Operating on a standard current with DC motors, these electric clamping systems include segmented punch holders, precision design, hard steel construction, and lots of lights. They also are very easy to maintain.

Electric clamping has a motor driving a screw for direct clamping. When the screw clamps and seats the punch tang, the punch becomes one with the holder. The punch holder can be spaced and used for height of punch when bending boxes. With this in mind, an operator can do the same flange height with a punch that is 6.4-in. tall rather than the 8.7-in.-tall punch in a solid beam used in the hydraulic system. Again, smaller tooling is good for the company because it is less expensive than the bigger and heavier tooling.

A light on each punch holder indicates to the operator if tooling is clamped. A quick visual inspection gives the operator the confidence that the job can proceed.

The press brake environment is a demanding one and always runs the risk of potentially damaging tooling. Electric clamping isn’t a shield from this risk. If the body, motors, or lighting are damaged, there is no maintenance technician required. The press brake operator can replace the damaged component. The brake can be up and running quickly in minutes by spacing punch holders or replacing components if they are on hand. Neither completed assemblies nor components require a truck to transport, so components can be overnighted if needed.

Clamping continues to evolve as companies in North America compete with the world. Clamping is a segment of a much larger system within each shop. More technology will continue to be added to clamping to make systems smarter, easier, and reduce downtime.

Taking guesswork out of clamping is something that press brake manufacturers are very interested in because it’s one less thing with which an operator has to be concerned. With so many press brake experts retiring and less-experienced operators replacing them, metal fabricators recognize that simplifying the bending process helps to get these new operators contributing much more quickly than if they were working with older brake technology.

Editor-in-Chief Dan Davis can be reached at [email protected].

Steve Brown is the bending product manager for Wilson Tool, 12912 Farnham Ave., White Bear Lake, MN 55110, 866-752-6531, wilsontool.com.