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Plasma Technology

More cutting speed

By Russ Olexa

February 2011 - As customers demand more services from steel centers, many are providing secondary metal-cutting capabilities using saws, shears, lasers and plasma systems. For some steel service centers, like Stark Metal Sales Inc., Alliance, Ohio, it is a source of revenue and can help gain clients.

Started in 1989, Stark Metal now has 75,000 sq. ft. under roof with 43 employees. "We are a general-line steel service center dealing in carbon- and structural-steel products," says Dave Rownd, vice president. "We handle general carbon steels like A36, A572, AR400, 1018 and some alloys." Rownd notes value-added secondary services such as cut-to-length or cut-shape services generate 60 percent of sales dollars.

"Of our sales dollars, 30 percent is in plate burning for steel that ranges from 1/8 in. thick to 8 in. thick using both oxy/acetylene and plasma systems," says Rownd. "Then 55 percent of our sales dollars are in merchant products comprised of angles, channels, flats and structural-steel shapes. Then the rest of our sales dollars are generated by flat-sheet-steel products along with pipe and tubing."

Offering secondary services is important, Rownd says. "There is a need for it from our customers. It takes a considerable outlay of cash to purchase plasma machines and saws. A lot of our customers either can’t afford it or choose not to own their own machines but need the parts produced by this equipment. It’s also a better way for us to service our customers, giving them a product that we can provide, along with increasing our margins."

Rownd purchased three plasma systems to increase the company’s cutting capabilities. Stark also has five saws, two shears and two oxy/acetylene flame cutting systems, allowing workers to cut steel up to 6 in. thick.

"We had to differentiate ourselves from the other steel service centers. And how do we do this? We do it by the value-added processing that we provide our customers. We offer them tight tolerances and secondary operations and quick turnarounds," says Rownd. "It’s my belief that in this business you have to out-service the competition to stay in business."

New plasma system
After researching technologies for a third plasma system in November 2008, Rownd eventually purchased a STI-200 HD Plasma System from Sector Technology Inc., Nicholasville, Ky. It uses products from Cleveland Motion Control, Cleveland, such as the Burny 10 CNC controller, Burny motion-control units, the Kaliburn Spirit 400a plasma power supply and an Inova height control for the torches.

Rownd now has three plasma systems with two using high-definition power supplies. One of the plasma tables is 12 ft. by 24 ft. with four oxy/acetylene torches and two plasma heads. The second table is 16 ft. by 50 ft. with two plasma heads that have been upgraded with high-definition cutting torches. The STI-200 has a 16 ft. by 40 ft. table with two plasma heads and integrated Cleveland Motion Control products that comprise a complete plasma system.

Cleveland Motion Control’s Kaliburn Spirit 400a plasma cutting system offers precision, high-current-density plasma cutting and marking, according to the company website. It delivers cut-edge quality with bevels of 2 degrees or less. It has a 400-amp power output to cut steel up to 3 in. thick and high processing speeds with exceptional consumable life. It automatically sets process parameters to allow exceptional ease of operation.

Using an automatic gas console on the Spirit 400a, an operator selects the material type and thickness for the cutting parameters, and the rest is automatic.

"When we bought the STI-200 HD, there was a big thrust in 2006 and 2007 where everyone was buying high-definition plasma tables," says Rownd. "It was the thing to do, and everybody had money because the economy was good. I didn’t want to make the move then because everybody was buying a machine that was able to pierce and production run 1.5-in.-thick plate.

"We heard that the technology was coming to cut 2-in.-thick plate, and I was sitting on the fence waiting for this to happen," he says. Then Rownd saw the STI-200 HD with the Cleveland Motion Control Kaliburn power supply. After seeing a demo, he learned the technology would handle pierce and production work. "This equipment allows us to pierce in the middle of a 2-in.-thick steel plate. This is a big advantage for us, and we pulled the trigger to buy it," says Rownd.

Competitive advantage
Rownd purchased the plasma system prior to the recession, but many other companies did not make similar purchases. This made Stark the only company in its market with the ability to pierce and production run 2-in.-thick, high-definition plasma cut parts. "For the last year and a half, we are the only company that has been offering this type of service. Plus, it has helped us bring in additional work."

Rownd says the company didn’t look at any other manufacturers when it was presented with the STI-200 HD because no other manufacturer had the cutting capability at the time. "The price of the machine was comparable to what we would’ve paid for a lesser quality one," he says.

One of the reasons Rownd wanted a plasma system that could cut 2-in.-thick steel plate was its cutting speed. "We run 2-in. plate at 30 to 40 ipm," he says. "When you run this type of plate using an oxy/acetylene system, you’ll cut at between 8 to 10 ipm. So it’s easy to do the math. For each plasma torch, I’ve got to have about four oxy/acetylene torches. Therefore, my two-torch plasma machine acts like an eight-torch oxy/acetylene cutter.

"What really comes into play is when we aren’t doing multiple parts. If I have a piece of 2-in. plate that I’m only burning larger parts from, and I’m running about 40 ipm using one plasma torch instead of one oxy/acetylene torch, I’ve completed the job in about 25 percent of the time. In a steel service business it’s all about equipment uptime. How many plate rotations you can get on a plasma system on a shift or how you can get to the next job faster. Having a large plasma machine like this is just so much better than an old oxy/acetylene burning system."

Rownd says a fabricator for which he completed a job told him it saved a large amount of welding setup time for its 13/4-in. and 2-in.-thick steel parts that came off the STI-200 HD that were flame cut before. The precision of the plasma system cut parts saved him between 20 percent and 30 percent of his welding fitup time.

The STI-200 HD plasma system can hold tolerances better than 1/16 in. in 11/4-in., 11/2-in. and 2-in.-thick plate. "Which is better than what any other company is doing," says Rownd. "We’ve been able to hold less than a 2-degree bevel on all of our parts."

When compared to its older plasma systems, the Kaliburn-equipped STI-200 plasma unit "is faster than our other plasma systems. However, we tweak everything. We are always trying to get the best quality at the best speed. When I look at our feeds and speeds chart for the STI-200, we are about 20 percent faster than our speed charts for our other plasma systems." FFJ

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Sources

  • Cleveland Motion Controls
    Cleveland
    phone: 216/524-8800
    fax: 216/642-2199
    www.clevelandmotioncontrols.com

  • Sector Technology Inc.
    Nicholasville, Ky
    phone: 859/881-8113
    fax: 859/881-8114
    www.sectortech.com

  • Stark Metal Sales Inc.
    Alliance, Ohio
    phone: 330/823-7383
    fax: 330/823-5949
    www.starkmetal.com

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