Laser Technology

When parts warp

By Russ Olexa

November/December 2010 - When its laser-cut parts wouldn’t meet its customers’ flatness tolerances, Angeles Steel Manufacturing Group, Santa Fe Springs, Calif., looked for a way to make them flat. The company’s solution cut down on distortion, and it provided other benefits, too.

Started in 1935, Angeles is among the larger West Coast fabrication and steel-processing facilities, says Faruk Zia, general manager. Recently, Namasco Corp., Roswell, Ga., a large steel service center in the United States and wholly owned subsidiary of Kloeckner, a Germany-based company, purchased Angeles.

Angeles began as a small welding shop and grew. One of the strengths is its 220,000 sq. ft. manufacturing facility that houses equipment capable of building nearly any type of part from machined ones to large fabrications. The company is split into three segments: steel processing, fabricating and precision manufacturing, says Zia.

"For precision-manufactured parts, we service companies like Siemens Corp., [Washington, D.C.,] as a Tier 1 supplier," says Zia. "We also produce parts for light rail, which requires a smooth surface and a tight flatness tolerance, and we work for some manufacturers, such as The Boeing Co., [Chicago,] along with other companies that require precision parts that have very tight tolerances." Angeles also builds large pressure vessels, weldments and structural steel fabrications for the solar, oil and gas industries and parts for the transportation and mining industries.

"We act as a steel service center for a portion of our business, having been integrated into Namasco’s steel supply and distribution business," says Zia. "But we’re still a one-stop shop."

With a laser, high-definition plasma, shears and an oxy/actylene system, the company can cut thin sheet steel to thick plate. However, for some laser-cut parts, the company was experiencing warpage after cutting, which was a problem for some customers, such as Siemens.

"The flatness requirements of our customers were such that if we bought milled plate or took a coil and converted it to cut-to-length plate, there was still [coil-set] memory left in the steel, and it wasn’t as flat as it needed to be," says Zia. "We couldn’t just take plate and level it to give them the tolerance they needed. Also, when we were burning plate or laser cutting it, the heat would sometimes distort the steel."

Looking for a solution
Zia realized a precision leveler would be the best equipment for Angeles. It needed one with a conveyor system that workers could load with cut parts and the machine could feed itself. After reviewing several manufacturers, Angeles selected Arku Coil Systems Inc., Cincinnati, and purchased a FlatMaster 80 that can handle parts up to 7/8 in. thick, 63 in. wide and 20 ft. long.

"Now, after laser cutting a part, to make it absolutely flat and smooth, we run it through the Arku FlatMaster to get to the tolerances needed," says Zia.

"Large sheets of steel often have a lot of stress caused by the steel’s milling process," says Patrick Jobst, Arku coordinator for sales and engineering. "There is tension and other forces trying to springback the metal. Often after laser cutting, the parts somehow twist when the stresses are relieved from cutting."

Arku’s FlatMaster uses steel rollers and an internal hydraulic system to level parts. The machines are equipped with a gap-control system, too. If the gap between the upper and lower leveling rollers changes, the leveler detects this and produces a counteracting force on the rollers within fractions of a second. Powerful hydraulic cylinders apply pressure at the front corners of the machine. This produces a constant leveling gap at all times.

The Arku FlatMaster’s roller leveling involves a bending process, says Jobst. A series of alternate bends within the machine deform unleveled sheet metal parts. Passing the part between the upper and lower sets of leveling rollers within the equipment creates alternate bends. The rollers are offset by half the roller spacing in the direction of travel, which results in the part taking a wave-like path through the machine. "After leveling, parts are flat and nearly stress-free," says Jobst.

Arku’s FlatMaster also has overload protection for its hydraulic system. When leveling thick plates, high forces can occur on both the leveler and the metal. If the machine is adjusted incorrectly, it can cause several components of the leveler to overload. With the FlatMaster’s overload protection, this can’t happen, says Jobst.

"Also, to keep parts clean, the FlatMaster has a quick-change system that allows the roller unit to be removed for thorough cleaning. This eliminates errant materials getting on the leveled parts," he says.

Depending on the material thickness, Arku has different machines with different-sized leveling rollers. "For instance, we have a machine with 30 mm leveling rolls that has a part thickness range from 0.35 mm up to 5 mm. The next series of machines are our hydraulic FlatMasters. They have more power and larger roll sizes for thicker materials. The FlatMaster series offers different machines with 50 mm, 80 mm, 120 mm and 180 mm leveling rolls. The bigger the roller diameter, the thicker the material that can be leveled," says Jobst.

Stock material
Angeles also discovered an additional use for the Arku FlatMaster. "Although it wasn’t intended, we actually ended up using the leveler for our stock material," says Zia. "When we have wavy plates or other coil problems, we run this material through the leveler and flatten it.

"If there’s a problem with sheet or plate steel, we lose the value of the material, and we have to sell it as a second. By running it through the FlatMaster leveler, we take the kinks out and make it smooth. We can sell it as prime material. This was somewhat of a byproduct of owning this equipment."

Angeles bought the Arku FlatMaster because of Arku’s reputation, says Zia. "We heard about their FlatMaster and also their service program. They are committed to servicing the United States from their Cincinnati facility they opened and keeping spare parts supplied. They were much more aggressive in terms of their commitment here than the other companies we reviewed," Zia says. FFJ

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  • Angeles Steel Manufacturing Group
    Santa Fe Springs, Calif.
    phone: 800/565-4880
    fax: 562/699-2115

  • Arku Coil Systems Inc.
    phone: 513/985-0500
    fax: 513/985-0580


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