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Going beyond commodity sheet metal perforation

How a Chicago perforator expanded into precision sheet metal fabrication

Figure 1
This complex part involves both perforation and precise forming.

The perforating industry once consisted of numerous small players clustered around Chicagoland and Pennsylvania. The shops initially formed to serve the needs of the agricultural equipment and (especially in Pennsylvania) mining sectors. But over decades the business changed. The perforation process itself had become viewed as a commodity service, and that in turn led to consolidation. Today only a handful of large players remain, and one of them is Accurate Perforating (AP), a 200-employee operation based in Chicago.

But about a decade ago, AP started to follow a new path. Managers didn’t want the company to produce just the perforated sheet. They wanted to fabricate and assemble that sheet into something larger and more complex.

Today the company is no longer just about making holes; it’s about making components that OEMs can place easily into their final assemblies, and contractors can quickly install onto buildings (see Figures 1 and 2). That’s far different from what the company was seven decades ago, when a scrap peddler named Ralph Cohen fell in love with perforating—not for the hole-filled sheets the process produced, but what those sheets left behind.

For the Love of Slugs

Before launching AP in 1942, Cohen had no intentions of becoming a perforator. He reveled in the deal—buying scrap low and selling it high—and some of his largest sources for scrap happened to be the perforation houses around Chicago.

“He was always a peddler at heart, and he became fascinated with his perforating clients because of the amount of scrap that they generated,” said Aaron Kamins, Cohen’s grandson (on his mother’s side), who took over as president 10 years ago. “He fell in love with the byproduct—the slugs that he would get from the perforators, and he said, ‘You know, I could develop those slugs myself.’ So he put in his first machine to generate those slugs.”

During the early years the perforation work complemented Cohen’s primary scrap business, but over the years this gradually shifted more toward perforation. AP moved into its current facility in 1952 and remained a small enterprise for decades. Then in 1982 managers jumped on an opportunity to purchase Standard Perforating, a competitor just a few miles away that had just undergone a labor dispute with its union and was struggling financially. AP moved Standard Perforating’s employees and machines over to its own facility. “That basically doubled the size of the business overnight,” Kamins said, adding that in 2002 AP purchased another Chicago-based perf house, Semrow Perforated Products.

Such bolt-on acquisitions were typical in the perforation business. AP’s managers could see the consolidation trend, and they knew what was causing it. Basic perforation was being perceived as a commodity service, and to compete, successful perforators were purchasing less successful ones. But they also knew that consolidation couldn’t continue forever.

For years the company had made its mark with complicated perforation projects, including dramatic building facades, ceilings, and complex screens for OEMs—hardly a commodity service, but certainly within the capabilities of the country’s remaining perforating shops. Everyone’s principal value proposition remained rooted in the perforation process itself. At Accurate Perforating, this was soon to change.

Foothold in Fabrication

For decades AP has performed shearing—and it’s not an everyday shearing process, either. Some shearing takes place automatically in a separate station, connected to the press control, as the sheets emerge from the die.

Figure 2
Accurate Perforating supplied complex panels for this office building outside Philadelphia.

Certain jobs, such as one in which each panel is a different size, each with an unperforated margin around the edge, require a secondary shearing process. A technician places pins in the last row of perforations, which stick up and allow the shearing operator to gauge off the edge of the perforation (the critical dimension) and not the edge of the blank.

Besides shearing, though, the company’s fabrication offering in the 1990s wasn’t extensive, and it certainly didn’t include comprehensive assembly or welding services. Between 2000 and 2005, Mike Beck, director of architectural and engineered sales, and new product development, helped bring in machines to expand AP’s capabilities. “Our existing customer base’s demand for fabrication was really growing,” he said.

Then in early 2005 came a phone call that accelerated the company’s push into fabrication. It was a contractor for the new American Airlines World Gateway terminal at JFK, and he had a problem. The new concourse had thousands of perforated ceiling panels. The perforations weren’t terribly unusual—0.125-inch-diameter holes punched in 0.050-in.-thick aluminum; the holes’ staggered orientation (lining up horizontally but not vertically) aided noise reduction and airflow.

Fit-up between the panels was critical, and this was what the contractor called about. Thousands of panels had arrived at the site, perforated and with edges flanged, but when they were installed, some bowed slightly. Many panels had dimensions that weren’t exactly what they should have been, and this wreaked havoc on fit-up. On top of all this, many panels arrived at the site severely damaged.

The contractor sprung the question: Could AP provide dimensionally accurate perforated panels? One more thing—the grand opening is just 90 days away.

AP dove into the job, manufacturing 17,000 panels with acoustic backing material and the proper perf patterns that ensured noise reduction and proper airflow. It worked with a corrugated box manufacturer on packaging so the panels would arrive at JFK without a scratch.

Most significant, at least when it comes to the company’s evolution, was AP’s work with Advanced Display, a precision sheet metal fabricator in Chicago. At the time, the fabricator focused on the point of purchase (POP) display industry (hence the fabricator’s name), but contracted with different companies as well, including AP.

Advanced Display had the precision press brakes and forming expertise this job required, plus the capacity to manufacture the panels within the short lead-time required. The 2- by 5-foot perforated panels required a tight dimensional tolerance in length, width, and edge-flange depth.

Working together, AP and Advanced Display churned out 170,000 square feet of perforated panels, fabricating and painting them on time to be painted and installed before the grand opening in July 2005, when then New York City Mayor Michael Bloomberg spoke below the space-age, dramatically white ceiling of the new Terminal 9 (see Figure 3).

As Kamins recalled, “After this collaboration, we knew we wanted to buy this company.”

Figure 3
Accurate Perforating provided 75,000 formed and perforated ceiling panels of Terminal 9 at JFK Airport.

The deal didn’t come about because Advanced Display’s owners were looking to retire or otherwise exit the business; they are still very much part of the enterprise. It wasn’t a bolt-on acquisition, either, like AP’s earlier purchases. The move was strategic, Kamins said, and came about because everyone agreed the two companies could compete better together. “It helped us, as part of the perforating industry, to move from a commodity supplier to a more components-based supplier.”

“We realized more customers were asking us to provide metal fabrication services, and we knew we needed to add those capabilities,” said Damon Henrikson, AP’s director of marketing. “It also allowed us to offer shorter lead-times. You can outsource only so much for so long.”

After the acquisition, Advanced Display changed its name to Accurate Metal Fabricating. The new division gave AP not only more fabrication capabilities—laser cutting systems, CNC turret punch presses, advanced CNC press brakes, and welding—but also a platform to move into more assembly work (see Figures 4 and 5).

Since 2006 Accurate Metal Fabricating has expanded beyond the POP industry, which can be unpredictable and difficult to standardize, because one job is entirely unlike the next. “Each POP job is basically one-and-done,” Kamins said. “You tool up to work on a POP job for a month, and then you never see that same job again. We wanted to move toward longer-life-cycle projects. So now, for instance, we do work for farm implement companies in which we expect to have about a 10-year product life cycle.”

Kamins added that longer product life cycles opened up more continuous improvement opportunities beyond 5S, changeover time reduction, and the like. For its repeat work, Accurate Metal Fabricating identified value streams, moved machines, and perfected part flow.

The repeat work also led to new manufacturing technology, including a robotic welding cell designed around the needs of a customer in the lighting industry. The cell uses Fronius’ cold metal transfer gas metal arc welding, a low-heat-input process especially suited for the fabricator’s thin-gauge aluminum work. For the lighting customer’s job, the robot welds eight times faster than the previous manual gas tungsten arc welding process.

The organization now can offer products that involve both perforation and fabrication, and this again includes products for the lighting business. For years AP sold plenty of perforations to various lighting industry players, but usually just the flat sheet. Now the company offers complete components, such as a perforated baffle system that can have between 25 and 50 assembled components. Before 2006 the organization could have provided the perforated housing and a few of the basic bends, but that’s about it. Now, except for powder coating (AP uses several nearby custom coaters), the company can handle the entire project.

Another example: AP makes numerous air intake covers for agricultural equipment. Years ago the company provided just the fabricated sheet. Now AP cuts the perforated sheet to size, corrugates it (positive and negative bends made on the press brake or panel bender), assembles it to a metal frame, and sends it out for painting. “Now the agricultural equipment customer can take that air intake cover and put it right into the tractor that it’s building,” Kamins said.

Holemaking on the Level

Because the perforation press creates a large area of holes in one hit with one die, it tends to distribute forming stresses evenly, but the unequal stresses are still there, and this causes distortion. Plate that is 0.25 in. thick emerges from the perf press almost in a half-moon shape. “It curls the entire sheet,” Henrikson said, “but it curls it evenly.”

Figure 4
A technician at Accurate Metal Fabricating welds a component for the point-of-purchase industry.

Making hole-intensive patterns on the turret punch press, technicians can try to minimize stress by punching in different areas of the sheet, starting away from and moving toward the clamps. And they use machine features that change the approach speed of the ram, or use the stripper to hold the workpiece in place before the punch contacts the sheet surface. All this helps distribute the stress induced by the punching force. All the same, for many jobs the distortion is, again, still there.

For this reason, the company sends all perforations and other hole-intensive jobs through one of seven high-powered Herr-Voss Stamco precision levelers, which equalize the stresses to produce a flat, perforated sheet. The levelers handle everything from 0.012- to 0.312-in. sheet (though thickness capability depends on material type).

“We put a lot of stress into the material,” Kamins said, “but we have a way of taking that stress out.”

“It takes a thick, U-shaped plate, even stainless steel, that looks like we never could use it,” Henrikson said. “We send it through our CNC levelers, and it comes out perfectly flat.”

This has allowed the company to tackle holemaking work that couldn’t be done without subsequent leveling. The leveling also makes the punched blanks consistently flat for downstream forming and assembly, especially for the component work that flows through Accurate Metal Fabricating.

High-powered leveling has also played a part in AP’s SuperPerf process, which breaks the rules of perforation by allowing for extremely small hole diameters in thick materials. Traditionally, if engineers wanted perforated stainless steel, they chose a hole diameter that’s larger than the material thickness. Now they can perforate stainless with hole sizes up to 40 percent less than the material thickness. The process involves not just leveling, but also proprietary approaches to tooling and pressworking (see Figure 6).

The manufacturing method opens up new design possibilities. For instance, agricultural and food processing equipment-makers may use certain perforated sheets that need to be replaced after so many months. But a sheet that’s thicker and perforated with smaller holes may mean that the sheet needs to be replaced only every few years. SuperPerf costs more than traditional perforation, of course; but in this case (and, the company hopes, in many others), the overall savings would be far greater.

“Consider a hammer mill [used to crush or pulverize material],” Henrikson said. “You will increase the life of your hammer mill screen and reduce the maintenance required to change out that hammer mill screen, all because you’re using thicker material with smaller holes.”

Quantity Considerations

When it comes to making holes, it’s hard to beat a perf press’s productivity. “On each stroke we can be punching up to 1,600 holes,” Kamins said. “You just can’t do that using any other technology.”

“This is high-speed stamping,” Beck said. “Our perf presses run at 300 strokes per minute.”

Figure 5
Accurate Perforating’s purchase of Advanced Display in 2006 gave the organization more fabrication capabilities, including precision bending, as well as a platform to move into more assembly work.

Multiply this by the 25 perforating presses AP has on its floor, and you get a whole lot of holemaking capacity (see Figure 7). With throughput like this, perforation presses thrive on high volumes. The CNC presses can perform skip feeds, leaving a section of the strip unperforated. Some tools can have block punches to make square or rectangular cutouts within a perf pattern. But for the most part, the process’s sweet spot is consistent hole patterns.

High-volume holemaking goes to the perf presses; low-volume holemaking work goes to the turret punch presses—but what about the volumes in between? “For some applications, if we cluster-punched a job on a turret press, we wouldn’t have enough time in the day,” Beck said. “A job may call for 150 sheets, and each one would take about two hours on the turret press, simply because of the number of holes. And we have just five turret presses.”

If hole patterns in that job vary greatly, then yes, a large contract fabricator with 15 or 20 turret punch presses may be able to process the job in less time. But if the hole patterns are consistent, that’s another matter.

“We have more than 2,000 standard tools in inventory for our perforating presses,” Beck said. “And all the punches are removable within the tool, so you can pull them out to get different widths, different patterns, or strips of unperforated area within the part.”

Beck added that most perforating shops also have large tooling inventories and would be able to do the same. What many do not have, though, is the ability to fabricate and assemble a larger component.

Branding With Holes

Many OEM and POP customers have approached AP about a way to design their brand logos into a perforated sheet. AP employed programmers experienced in hole-intensive jobs on the turret punch press, and programming logo shapes, while intricate, wasn’t a major challenge for them.

As Kamins recalled, “After we did this, several clients came to us with a picture and asked, ‘Can you punch this?’”

Kamins added that the request evolved into a service AP now calls Picture-Perf, in which the company punches holes in a pattern that creates a logo, graphic, or picture.

“We saw similar things done in different ways before,” said Beck. “So we asked, ‘What if we use different-sized holes with different open areas and spaces between those holes?’”

Figure 6
Accurate Perforating’s SuperPerf, a proprietary process, allows the company to perforate small holes in thick materials.

The pattern can be small, in the corner of one panel on a POP display, or cover a building facade. For the new apartment complex in downtown Chicago, AP is providing 51 panels, each 5 by 13 ft., that when assembled depict a giant picture of the Greek Parthenon (see Figures 8 and 9).

Picture-Perf, and the Parthenon building project in particular, epitomizes AP’s strategy. About 90 percent of the building is covered with perforated panels, all made with perf presses. The remaining 10 percent—the high-value part of the job—entails irregular but extremely precise hole patterns produced via careful programming of the turret punch press. One out-of-place hole can ruin the entire picture.

When you think of a commodity, this is the polar opposite.

Photos courtesy of Accurate Perforating Co. Inc., 3636 S. Kedzie Ave., Chicago, IL 60632, 888-723-8108, http://accurateperforating.com.

Perf Press QDC

Years ago every operator at Chicago-based Accurate Perforating changed out his press differently, but about three years ago the company stepped up its continuous improvement efforts. Now operators work under a standardized quick-die-change (QDC) process. Pit crews stage the tools before the previous run is finished and help the operator perform the changeover.

“We built tool cabinets so that all the tools needed for the operation are sitting right there,” said Mike Beck, director of architectural and engineering sales and new product development. “The operator no longer needs to walk two presses down and say, ‘Hey! Johnny, I need a wrench.’”

“It used to take us between four to five hours to change over a perforating press,” said Aaron Kamins, company president. “Today it’s down to 30 minutes.”

The improvement continues. Periodically a team films changeovers, critiques them, and develops recommendations to streamline the process even further. Eventually some of those recommendations are implemented as part of a standard die-change procedure.

Die maintenance is well-documented, and grinding of pin-punches and base plates occurs based on the type and thickness of material the tools have been used for. A die used for carbon steel may last two to three days without being sharpened, while a die used for stainless steel may need to be sharpened after four hours of use.

About the Author
The Fabricator

Tim Heston

Senior Editor

2135 Point Blvd

Elgin, IL 60123

815-381-1314

Tim Heston, The Fabricator's senior editor, has covered the metal fabrication industry since 1998, starting his career at the American Welding Society's Welding Journal. Since then he has covered the full range of metal fabrication processes, from stamping, bending, and cutting to grinding and polishing. He joined The Fabricator's staff in October 2007.