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Coil Processing
Wednesday | 05 February, 2014 | 10:11 am

Achieving true flatness

By Bob Sipp & Kelly Konrad

leveltek

Above: The Benwood Wide Line located at the Benwood, W.Va., facility processes all coiled metals, without marking, to the highest global standard for laser-quality sheets up to 1⁄2 inch x 96 inches at any length, as well as coil-to-coil. Metals can include bright-annealed stainless and painted/embossed or P&O carbon steel. Even they will have no marks from Leveltek’s gripper technology

Defects in materials are rarely acceptable, and for some industries, they’re simply not an option

February 2014 - “As shop floors become more like high-tech labs, isolation of precision equipment is a growing area of concern,” says Sam Smolen of Salem, Mass.-based Soundown Corp. “Custom isolation pads combine a metal plate and specialty elastomer to reduce transmission of vibration that can affect accuracy, damage equipment, and result in elevated noise levels.” To make these simple but high-tech isolation pads, the company requires truly flat metal sheet.

Soundown manufactures sound control componentry for the marine industry and other applications. The company works with Leveltek Processing LLC, Benwood, W.Va., to meet its stringent requirements for flat metal sheets. “Leveltek-flattened plates result in a consistent substrate that allows Soundown to deliver solutions with class leading performance to production, lab, research and medical facilities around the world,” Smolen says. “Our mill source guided us to Leveltek for processing technology solutions, for perfect flatness and memory-free metal for use in our lasers and demanding substrate applications.”

When Leveltek Processing was founded in 1993, its main focus was toll processing coils of stainless steel for a mill in Pennsylvania. Its own nonmarking gripper technology could be applied in coil-to-coil leveling, meaning customer processing costs were lowered while product quality increased significantly. 

LEVELTEK

Word of its success spread internationally and soon European stainless mill executives arrived at Leveltek’s small plant with a request to stretch level their Italian-made, bright-annealed stainless coil without marking. The resulting installation of a machine in Italy spawned Leveltek International LLC.

“Leveltek Processing LLC adds an important asset to its sister company, Leveltek International LLC, the group’s design/build/technology operations,” says Leveltek vice president Nick Yavelak. “It provides a round-the-clock research and development working laboratory for continuous improvement of leading preparation technologies for flat metals. It also provides constant toll-processing customer feedback on the newest metallurgies as coiled metal arrives from points around the globe. Its unmatched machinery provides customers the opportunity to test and verify true laser-quality metals performance and performance/cost comparisons before LI’s machinery customers commit to capital expenditure budgets for new processing machinery choices.”  

Leveltek International has now been offering its nonmarking stretch leveling systems for 20 years. The technology, recognized this year by Global Metal Awards as the best for shape correction and laser quality, is used with coiled metals in both coil-to-coil and coil-to-sheet formats, and technological advances mean Leveltek products now are capable of stretch leveling any coiled metal, regardless of width, gauge or type. 

Roller leveling remains the largest installed technology for leveling in the world, and although it makes materials look flat to the eye, the metal actually takes on a radius shape reflecting the last set of rollers over which it passes. “Remember, even enhanced or differential speed roller levelers contact 100 percent of the strip surface area, adding memory to the metal by serpentine passing through multiple sets of large and small rollers,” says one mill customer. Similarly, in tension leveling or enhanced roller leveling, these levelers also impress any dirt or roll deformities permanently into the strip, every 360 degrees of roll rotation, under high tension.

Leveltek’s soft grippers stretch galvanized steel and coated steel mark-free, bright-annealed stainless without marking its mirror finish and painted embossed carbon without marking its paint. Plus, because Leveltek stretch leveling machines uniformly stretch the material across its full cross section, Leveltek equalizes all internal stresses resulting in truly flat, memory-free material.

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Unlimited sheet lengths

In December 2011, Leveltek Processing installed one of the world’s largest stretch leveling lines at its Benwood plant. Known as the Benwood Wide Line, it is capable of processing all coiled metals, up to ½ inch thick by 96 inches wide. Originally designed for an aluminum plant contract, it now processes aluminum, stainless steel, carbon steel, titanium, aerospace alloys, brass, bronze, painted and embossed carbon steel, pickled and oiled carbon steel and carbon, stainless and aluminum diamond plate. 

The Wide Line serves many markets, including aerospace, transportation, earthmoving equipment, farm machinery, shipbuilding, commercial roofing and panels, food processing, appliances and other fabricating industries. One of Leveltek’s most versatile lines, it includes a recoiler, an orbital pallet wrapper, and both a flattener and roller leveler for cross-bow removal on high-strength materials. 

Like other Leveltek stretch leveling equipment, the Wide Line can convert secondary coils to prime and remove all length-oriented defects, inclusive of edge waves, center-buckle, and camber, even as the defect orientation and location change throughout the coil, and never with any marks. Leveltek’s soft grippers grab the metal with equal grip force distribution across the total strip width. This enables equalized stretching across the entire strip cross-section, allowing uniform grain alignment and total elimination of memory. Stretchers with metal grippers leave residual stress fields where the grippers grab the metal, adding to metal memory.

Because there is no need to shear on grip marks or adjust grip lengths, the soft grippers allow for unlimited sheet lengths within the same coil. “Even with Leveltek stretch lengths averaging 50 feet, sheet lengths of 60 feet or more are possible because there are no marks on any portion of any sheet length,” says Yavelak. “Sheet lengths are not limited by Leveltek technology, only by customer real estate constraints.” Globally, Leveltek International stretch lengths vary between 25 feet and 165 feet, the latter designed to provide high production coil-to-coil stretch leveling.

A good fit for niche manufacturing

Metal service centers like Washington, Pa.-based Camalloy Inc. often count on a quick response from their partners to meet their clients’ needs. Camalloy is a supply chain manager for special products and processing in niche manufacturing industries including elevators, metal fabricating, containers, HVAC, power generation, banking and medical. 

Because Leveltek is able to effectively and quickly respond to customer requests, Camalloy can respond in-kind for its customer base. “Fulfilling special-needs markets demands a highly responsive, dependable, every-option toll processor like Leveltek,” says Camalloy president Art Downs.

And their track record spells quality. All Leveltek stretch leveling machines built since 1993 continue to operate full time, with 99.3 percent up-time reliability—all while averaging a 99 percent yield on every coil. MM

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WHY LASER-QUALITY METALS?

THEODORE H. MAIMAN and his team built the first successful laser in California in May 1960. Since then one of the most important applications of lasers has been metals processing: cutting, forming, drilling and welding—a relatively new industry worth billions of dollars in revenue, and still in its infancy. Today there are more than 30,000 laser machines around the world cutting metal and that number is expected to double within five years.

Lasers are efficient, highly-productive and profitable but require very flat, memory-free material on the input side that will remain flat during the cutting process. Leveltek addresses this need with its commitment to controlling three primary parameters: 

Flatness: To maximize a laser’s accuracy and speed the laser head must be locate as close to the workpiece as possible. Any waves or buckles may cause interference or collision of the laser head with the metal.

Memory-Free: Providing flat feedstock is crucial, but the material also must remain flat when it is being cut. Metal coming off an uncoiler has an uneven distribution of stresses left in the material. If these stresses remain in the sheet they can allow the metal to spring back, upsetting or damaging the laser cutting head. Stretch leveling removes residual stresses in the metal so there is no spring back during cutting. 

Enhanced-Surface Quality: Laser speed and accuracy are affected by material surface integrity. Laser absorption efficiency is improved by stretch leveling technology facilitating better energy transfer and faster cutting.

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Contributor Bob Sipp is the Leveltek sales and marketing director.

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