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Coil Processing
Friday | 22 January, 2016 | 3:38 pm

A proper fit

By Gretchen Salois

Above: Entire cut-to-length line at Russel Metals, including the Braner stretcher-leveler.

An adaptable cut-to-length line keeps processor abreast of change

January 2016 - Lean inventory and just-in-time delivery are now standard so when a company is obligated to shut down a key piece of equipment to perform maintenance, the lost productivity can reduce revenues.

Mississauga, Ontario-based Russel Metals needed a new cut-to-length line that would keep productivity high. Each of its two locations in Winnipeg, Manitoba, provide different services. Its facility at the north end of the city provides flat-rolled material and general line products like a typical service center and its operation on the south side provides downstream processing including flat laser cutting, tube laser cutting, press braking and plasma cutting. The processed parts are used in the transportation sector, including railroad cars, trailers, buses as well as building construction and agricultural equipment. “Providing the downstream processing gives us a unique perspective,” says Terry Vanstone, project manager at Russel Metals. “We know what problems our service center customers face because we have to deal with them ourselves.”

While researching available technologies for the new cut-to-length line, Russel Metals found its choices were limited for the specific features it sought. Eventually, a line built by Braner USA Inc. allowed Russel to process a wide range of materials while minimizing downtime by using interchangeable roller leveler cassettes.

“We chose Braner because of their quick responsiveness to our questions while also providing cassette leveler technology,” says Vanstone. “We knew the cassettes would allow us to run a wide thickness range and also allow us to perform maintenance without shutting the line down.”

With cassette technology, Russel Metals can cut material ranging from 0.06-inch to 0.5-inch-thick on the same line. Routine tasks such as leveler roll cleaning or more extensive maintenance such as bearing and roll replacement can be done offline. “We purchased three separate cassettes which allow us to maintain two cassettes offline while we run with a third. In the past, we had to shut our line down completely for anywhere from a few hours to a couple of weeks, depending on the amount of work required,” says Vanstone.

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Braner helped Russel Metals  minimize downtime by using interchangeable roller leveler cassettes.

Furnishing flexibility

Using the existing cut-to-length line, Russel Metals expected to be down for at least four to six hours for maintenance or repair work. “What took a minimum of half to three-quarters of a shift is now done in minutes—it’s a big difference to our customers and allows us the flexibility we need,” Vanstone says.

Russel Metals cuts mostly carbon steel but also processes aluminum and other nonferrous metals. “Having three cassettes gives us excellent material flexibility,” Vanstone says. “The first cassette levels carbon steel up to 1⁄2-inch-thick, the second one levels carbon steel up to 1⁄4-inch-thick, and our third cassette is strictly dedicated to nonferrous materials.”

Once the newer line was installed in 2008, Russel Metals found that switching between thicknesses and/or materials was quick and easy, which comes in handy when orders requiring quick turnaround pop up unexpectedly, according to Scott Keeney, operations manager for the Winnipeg branch. 

As a job shop “we do get rush requests,” Vanstone explains. “If we’re cutting thicker material, say 1⁄2-inch stock, and a rush job comes up for thin gauge, it’s very simple to change from one cassette to another. We basically push a button to swap cassettes so the changeovers take less than 15 minutes.”

Stretch leveler retrofit

In 2013 Russel Metals sought to expand its services by adding a stretch leveler to its existing line in Winnipeg, making it the first service center in western Canada to offer that capability.

Thermal cutting flat-rolled material that has been roller leveled can present challenges because roller levelers leave a small amount of memory in the material. That is, a sheet wants to retain the curve of the coil instead of laying flat. “When there’s memory in the material and you perform any kind of thermal cutting—whether it be laser, plasma or burning—that memory is suddenly released, causing the metal to pop up and damage the cutting head,” Vanstone says. “That causes downtime and expensive repairs. Our roller leveler does a terrific job, but a stretch leveler removes all memory so the metal doesn’t pop up and hit the cutting head. With quality requirements becoming tighter and tighter, we needed to keep up with new technology.” 

The Winnipeg shop justified the stretcher leveler purchase “because of the downstream processing we do ourselves, as well the processing our customers do on the flat-rolled product we supply to them,” he continues. Russel Metals again chose Braner for the new equipment. “It seemed logical for us to work with the same vendor to ensure a seamless integration,” says Vanstone. “We’ve been very happy with the cut-to-length line, and they offered a good set of features for the new stretch leveler as well. As an added bonus, Braner bought the steel they needed from us—nearly 180 tons worth—to build the frames.”

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Example of dead flat, memory-free sheets with holes punched through.

Stretch levelers are designed to produce flat steel, but Braner’s machine differs from others, claims Ken Shoop, sales manager for the Schiller Park, Illinois-based machinery builder. “For starters, we don’t use castings or prefabricated frames. Our stretcher is assembled as a kit, tested at Braner, then disassembled and shipped to the customer’s plant,” he explains. “No permits are required to ship our frames and the customer can use existing overhead cranes for reassembly. Considering the entry and exit frames for a stretch leveler can weigh as much as 100 tons a piece, the shipping and rigging cost savings is substantial.”

The machine uses direct acting clamps that move straight up and down, instead of moving at an angle, which would be the case if using traditional wedges, says Shoop. “Direct acting clamps don’t mark material and don’t require any special covering on the clamps,” he adds, noting some manufacturers need to coat clamps with polyurethane or cover them with replaceable cardboard.

The control package provided by Braner integrates the stretch leveler with the rest of the line for seamless operation. “The stretching cycle is initiated automatically because we keep tabs on sheet length, number of sheets cut, and the amount of stretched material remaining,” explains Shoop. “Without that, it would be like driving a car with two gas pedals. We also track material so every inch gets stretched to a memory-free state, including material that was under the clamps.”

To ensure the material is truly memory free, Braner’s control package plots a “stress-strain” chart during each stretching cycle. “Material is clamped and then stretched beyond its yield strength with large hydraulic cylinders. When the stress-strain chart ‘knees’ over, we know with absolute certainty that we’ve exceeded the yield strength of the material and removed all memory. 

Line operators can save those charts mapping the entire coil for quality assurance purposes, Shoop continues. “As long as you have a stress-strain chart, stretch-leveling technology is simple. You don’t need any special operating skills like you do with a roller leveler.” MM

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