Above: The eDrive leveler and temper mill at Nova Steel.
When technology works well, word spreads
October 2013 - As steel mills continue to produce stronger steels, service centers find it necessary to invest in the latest technology in order to stay ahead. “The advent of the stretcher leveler has almost made conventional leveling substandard when it comes to removing coil memory,” says Scott Jones, president of Nova Steel Inc., Montreal, Quebec. Using faster, more precise laser and high-definition plasma cutting equipment, as well as moving toward lights-out manufacturing, has forced players in the steel cut-to-length leveling game to make big changes. “The cost of any kind of steel springback in the laser or high-definition process can be prohibitive. You can damage or break the tips and lose time and speed,” Jones says.
For nearly 10 years, Nova Steel had some success running a temper mill with an underpowered heavy-gauge leveler. “But we noticed in the last few years we were having trouble getting the heavier, higher minimum yield steels flat even though the coil set was eliminated in the temper mill,” Jones says. “We thought the solution was more cold reduction (up to 2 percent) in the temper mill, but our old single 300-horsepower motor and 9 roll leveler just couldn’t get it flat.”
After hearing about the success Columbus, Miss.-based Mississippi Steel Processing LLC’s president Chip Gerber was having with the eDrive leveler from Bradbury Co. Inc., Nova Steel decided to give it a try. “It didn’t take long to make the decision once we understood the design and the technology behind the eDrive,” Jones says. “The leveler we purchased is driven by two 400-horsepower motors with an 11-roll configuration—five over six.”
The first motor powers the entry rolls with a deep plunge that removes any residual coil set. The second motor powers the exit rolls at a slightly higher speed. “It’s the exit rolls where perfect flatness is achieved,” explains Jones. “Therefore, during the leveling process, there is also some stretching going on with the exit rolls running at a slightly faster speed than the entry rolls, which is what makes Bradbury unique.”
Brownie Cox, industry manager–flat products at Moundridge, Kan.-based Bradbury Co., says the combination of the temper mill’s quality finish and superior flatness of eDrive is unlike anything available. “The eDrive makes for the best looking laser and high-definition plasma parts I’ve ever seen,” he says.
The eDrive uses a combination of roll bending and tension to pull the waves and buckles out of the strip while aligning the stress so the product will stay flat after laser and high-definition cutting. “The burned parts are usually used in other processes downstream, such as robotic welding,” explains Cox. “To produce an accurate final product with increased production rates, the eDrive ensures material is flat and consistent.” The eDrives are used in coil-to-coil lines, insulated panel lines, new and existing cut-to-length lines, stretcher leveling lines, temper mill lines, perforation lines and specialty process lines.
Success comes standard
Other service centers are following suit in order to meet their customers’ needs, according to Cox. “In many cases, we have pulled out an old, tired leveler from an existing line, put in a new eDrive and the customer is able to see the change in the very first coil,” Cox says. With nearly 50 installations ranging from very light gauge material from 0.015 inch to 1 inch thick heavy gauge, Bradbury Co. offers a full range of machines.
“Laser flatness requirements and increased yields are making it more difficult for older levelers to process the material properly,” Cox says. “Replacement of the older leveler with the new eDrive produces material to the laser quality standards we have today.”
The efficiency of the eDrive has allowed Nova Steel to reduce the pressure applied on its temper mill by about half. “We used to cold reduce by 2 percent, and now we are closer to 1 percent—sometimes under,” Jones says. “It has basically cut the maintenance costs on our temper mill in half, and maintenance costs on the eDrive are minimal.” Jones adds Nova Steel has run the eDrive for 8 months without a roll change. When operators clean the machine, it only takes about two hours a month.
Nova Steel also finds the eDrive’s software helpful. “Another great feature of the eDrive is that all settings for our complete range of products have now been dialed in and the set-up for each coil is very user friendly,” Jones says. “We are very fortunate to have the temper mill and eDrive leveler in tandem. I believe we are the only company with that combination in North America.”
Investing in innovation
“The biggest obstacle to buying a temper mill is the upfront capital cost,” Jones says, “and relative to the gross margin on leveled sheet and plate these days, it no longer makes sense. When we originally bought the temper mill in 2004, our margins were north of 20 percent, but with the onslaught of stretcher levelers, we’re no longer there. Nobody in his right mind can justify a new $8 million to $10 million temper mill in this market, but if you’ve already got one, it’s a big advantage.”
With the eDrive backing it up, Jones believes Nova Steel will have superior quality and line speed. “In fact, the eDrive does a great job all on its own,” he says. “We just feel it’s flatness guaranteed with the temper mill—plus we get a nice, shiny or polished finish, which cannot be achieved with a stretcher leveler or a standalone eDrive leveler.”
The eDrive has evolved, especially during the last four years. Bradbury Co.’s FlatTrak strip evaluation system continuously scans the surface of the strip for edge wave, quarter and center buckle. It will detect crossbow while the line is running. The operator interface determines actual shape conditions in real time, allowing an operator to make informed adjustments to improve flatness.
“It is part of continuous innovation at the Bradbury Co.,” Cox says. “We are about to release our latest improvement for leveling—it is our new patent pending Bow Scout.”
Bow Scout is the company’s latest automation innovation in enhanced flatness leveling technology that senses and corrects up/down bow along the length of the strip. Bow Scout automatically adjusts the leveler to stay within set tolerances without operator intervention. This latest innovation from Bradbury Co. increases line efficiencies. The combination of eDrive, FlatTrak and Bow Scout ensures processed flat material sheet after sheet.
Attention to tight flatness tolerances and increased yields will only expand in the future. Bradbury Co.’s customers are increasingly processing with thinner steel at higher yields. Cox adds, “Our technology is proven and it’s out there. People are realizing its advantages.” MM
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