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Thoughts on punching tool management

Proper organization of tools in the turret can help a metal fabrication shop minimize downtime

Limiting tooling changeover maximizes uptime in punching machines.

One of the best ways to maximize uptime in punching is to ensure the right tools are in the turret. Any steps taken to limit tooling changeover helps to accomplish that goal. Images: LVD North America

If you live long enough, you realize that some things that were once considered old and a novelty work their way back into being a fashionable choice. Punching might be one of those things.

Dan Caprio has witnessed that cycle. He started his career working as a machinist with Strippit in the late 1970s, making punching tools, some of which he can still track down in the shop today because he recognizes the part numbers that he inscribed on the tooling. “Back then we didn’t have laser etching,” he said. Today he’s LVD North America’s punching product sales manager, and he’s spreading the gospel of the punching machine to a new generation of metal fabricators that are more familiar with laser cutting than they are with holemaking and forming on a turret punch. It’s almost the opposite of what a metal fabricator went through in the late 20th century when laser cutting technology was slowly finding its way into more North American metal fabricating companies.

Unfortunately, an unfamiliarity with punching machines can lead to poor decision-making in terms of how punch tooling is organized in the turret. If a fab shop doesn’t have the right tooling mix, punching efficiency suffers.

“It becomes a huge time constraint when you have to change tools out,” Caprio said. “Coming up with the correct tool load and trying to keep that load consistent so they can run all of their parts while minimizing their tool changeovers is critical.”

A fabricator never wants to be at a point where it is changing out all of its punch tooling. Caprio said it rarely happens now because no one wants to go through that again. A punching machine with 48 stations could occupy an hour’s worth of a technician’s time if all the tools in the machine had to be replaced. Switching out a couple of punching tools, however, takes only a few minutes. Caprio said that’s where a fabricator wants to be: minimal downtime and back to punching.

Before venturing into a discussion of proper tooling management inside the turret punch, Caprio stressed that a fab shop should determine if it has the right-sized turret for its operations. Spending excess time switching out tooling is an indicator that the machine might be too small to accommodate the amount of punch tooling needed or that another machine might be necessary. Sharing prints of parts that require forms, such as countersinks or louvers, and punched holes and shapes with a punching machine manufacturer can help the machine tool builder provide a fab shop with some guidance to help boost its punching capabilities.

Such a discussion also can open the door to learning about new tooling capabilities that a metal fabricator might not realize are available. “Even in this day and age, some people aren’t exposed to these new developments,” Caprio said. “They are caught up in their own business. They really don’t know what they’re missing.”

With that out of the way, let’s discuss some ways to organize the punch press turret for maximum uptime.

Plan for an “Active” Turret

“I’ve come up through the ranks. I’ve done a lot of programming. I’ve taught our programming software for years. I’ve also run the machines for years,” Caprio said. “The one thing I would tell customers as they’re looking to organize their tooling in the punching machine is to set the system and the software up for an active turret.”

The “active” sums it up nicely. The turret should include the tools that will be used 90% of the time, according to Caprio. (That’s why it’s important to share prints with a punching expert, so they can provide you with an idea of just what punch tooling is being used the most.)

Large-capacity turrets provide ample room for punch tooling placement.

Large-capacity turrets provide ample room for punch tooling placement. In this example, the turret has three programmable auto-index stations that can accommodate multitools, which contributes to even more tooling capacity.

“You are always going to want to have a parting tool in the auto-index station. You always want one square tool in the mix. So leave those tools in there all the time,” he said. “Just bring out the one, two, or three other tools that you need every now and then and change them out.”

Sometimes you can make do with what’s in the turret already. For example, rely on a nibbling tool or make a couple of extra punches rather than stopping the machine to change over to a special shear tool. Modern punching machines now reach speeds of up to 530 hits per minute, and that kind of punching power makes a good case for not shutting the machine down for a tooling changeover if the punching job can be completed with what’s in the turret already.

Educate Yourself on Tooling Capabilities

Caprio cited a recent customer interaction as an example of what can happen when a fab shop taps the knowledge of a punching machine expert. The metal fabricator sent him about 20 prints of parts they were processing on their punching machine. It wasn’t a lot of variety, but the 20 parts represented a good amount of work for the shop.

During the perusal of the prints, the LVD application engineers noticed a lot of countersinking and tapping. Upon further discussion with the client, they also discovered the shop was creating these forms outside of the punching machine. In fact, they were doing that manually.

“I said let us do that. The forming tools have come so far over the years that we can hold a repeatability of a thousandth of an inch in creating the depths required for a countersink,” Caprio said.

They suggested the new tooling, and the metal fabricator purchased it. In the end, the shop eliminated about 800 hours of manual activity spent creating the countersink forms and making the taps. (Caprio added that some of the latest tapping tools can create as many as 120 taps per minute. These tapping tools have an oil reservoir in the die of the tooling itself, so it self-lubricates as it runs.)

That’s a constant lesson for the new generation of metal fabricators, Caprio said, because they don’t realize that a punching machine is most valuable when it’s making forms, such as card guides or louvers. That eliminates downstream processing and the associated material handling involved. Being able to do it on the same machine allows the metal fabricator to get the part shipped out faster and, as a result, get paid sooner rather than later.

Now, if metal fabricators keep abreast of punching tooling advances, they know that when these types of tools first appeared on the market they had pretty high price tags. However, over the years, the prices have come down, and Caprio said that that they could end up paying for themselves pretty quickly in the right application.

Some Tools Don’t Need a Permanent Home in the Turret

While the goal is to keep most of the tools in the turret, some of them should be in there only when they are being used.

“When you have the louver tool in there, for example, you really don’t want that staying in the turret because that lower die sticks up higher,” Caprio said. “So you don’t want some sheet metal hanging on there. If you aren’t going to run a program that needs that louver, you are going to take that tool out of there.”

Anything that can be done to minimize crashes with the sheet metal is a proactive step in decreasing downtime. That is definitely something fabricators can appreciate, even if they have little experience with punching machines. Just ask a laser cutting machine operator if they have ever had a part tip up in the skeleton and then have that part collide with the laser cutting head. Thinking about how tooling affects sheet metal movement on the punching machine is a smart play.

Question the Use of Multitools

Multitools are a wonderful thing. A punching machine with a limited number of stations can expand its capabilities with these versatile punch tools. A multitool is basically a single punch form that contains multiple tools within that one package. These multitools range in size, having an additional three to as many as 30 different tools in the same package.

The punch tooling manufacturers market these multitools as a way for metal fabricators to expand the capabilities of their machines and reduce the downtime that is normally associated with tooling changes. Those are both true, but Caprio said that a metal fabricator also needs to consider a bigger question: Would the shop be better off with additional punching capacity in the form of a new machine?

Multitools have their place, but they are also slower when compared to tools that are designed for a singular purpose, Caprio said. Consider how a multitool operates: It sits in an auto-index station, which might turn at only 45 RPMs, and after it moves into position, it needs to rotate again inside the tool before everything is aligned for continued punching. That’s not the most efficient means of punching, especially taking into account the punching operation over several shifts. The lost seconds add up to minutes very quickly.

Everyone understands the importance of uptime in machine performance. These guidelines can help those new to precision punching get the most from their equipment.

And if you have questions, ask the shop veteran or the machine tool vendor. That’s the quickest way to go from industry novice to shop floor sage.

About the Author
The Fabricator

Dan Davis

Editor-in-Chief

2135 Point Blvd.

Elgin, IL 60123

815-227-8281

Dan Davis is editor-in-chief of The Fabricator, the industry's most widely circulated metal fabricating magazine, and its sister publications, The Tube & Pipe Journal and The Welder. He has been with the publications since April 2002.