Increased demand for improved material flatness has forced steel service centers to adapt to tighter customer requirements. Laser cutters and high-speed punching centers are at the forefront of the shift to leaner flatness tolerances. These tighter tolerances put many owners of older leveling systems at a disadvantage as they try to compete with newer technologies.
The problem is amplified by the broad allowances outlined by ASTM standards. These standards are rarely used or, at best, misinterpreted. The main difficulty with the standards is that they allow for a wider range of center buckle and edge wave than most customers will accept. New product designers and manufacturing companies with secondary processing equipment insist on closer flatness requirements, and modern leveling equipment will deliver better flatness than ASTM standards suggest.
Even the more recent I unit scale (ASTM A568) is widely misunderstood. For example, two I units can equal a 1/8-inch wave every 40 inches, a 1/16-inch wave every 20 inches or a 1/32-inch wave every 10 inches. All of these variations are equivalent, according to the I unit standard.
Getting to flat
To help solve the problem for owners and operators of both old and new levelers, The Bradbury Co. Inc., Moundridge, Kan., has introduced a system that measures strips being processed, records the data, analyzes the findings, prints the results and gives the line operator a real-time graphic of how the current strip rates before it leaves the leveler.
A team at Bradbury, led by Brownie Cox, senior sales advisor for flat products, has been developing the patent-pending system, named Flat Trak, for the past two years. "This is the next generation in flatness technology," says Cox. "The real-time display of the strip's shape allows the operator to view the effects on the material immediately after making a leveler adjustment."
In addition to the detailed display on the operator interface, a three-light status system alerts the operator to out-of-spec conditions. A green light indicates that the strip is within a preset acceptable range. An amber light warns that the strip is approaching an outer limit of the preset flatness standard. A red light alerts operators that material flatness is out of the preset limits, and they should re-evaluate the settings of the leveling equipment to bring the process back to the desired range. When coupled with a Bradbury hydraulic leveling system, a remote operator station and the light system, Flat Trak enables an operator to view leveler performance and adjust settings from a remote location.
In conjunction with putting the new leveling system on the market, Bradbury is initiating a new standard of measurement. Cox explains that "a strip with a 1/32-inch wave every 10 inches is not flat. The Flat Trak System will monitor and record the flatness of each finished pack and give it a score on a scale from 1 to 10. This new F scale (F stands for flatness) system is easy to use and understand."
Measurements are continuously taken across the moving strip and points are automatically compared to determine flatness at the edges, center and intermediate points. The unit can provide a printed label for the pack to indicate the maximum F value contained within that stack of sheets. It can also be set up to mark measured F values along the strip itself at programmable intervals.
What customers want
Bradbury expects that the new system will provide an increase in market share for service centers that employ the new grading scale. "It makes sense that companies that can guarantee strip flatness will get orders from customers who require it," Cox says. "And a leveled sheet with an F2 evaluation will bring a better price than an F6."
Users of the new system have been positive about its performance. "We like Flat Trak," says Doug Stein of Douglas Steel in Vernon, Calif. "It makes it easier for the operator to understand what's happening, and the combined Bradbury leveler and Flat Trak system we're running do a better job of turning out flat sheets than the other top-name levelers we have.
"I'm convinced it's a worthwhile investment," Stein says. "Operators can tell in advance if they are getting flat sheets long before they have to pull them off the machine and test them. This saves us a lot of time and trouble," he says. "If a sheet isn't flat and we don't find that out until it's off a leveler, then we have to run it back through and re-level it to correct the problem.
"Flat Trak gives us a flatter product on the first pass with less skill required of the operator," Stein adds. "In the final analysis, it is the operator's skill that determines the quality of the product, and the right people are hard to find. So a system that doesn't put such a high demand on the operator speeds production, makes our job easier and helps reduce our costs."
Bradbury partnered with Delta Metals, Memphis, Tenn., as the Beta site to test the first Flat Trak on the company's cut-to-length line. The line has two Bradbury hydraulic levelers in tandem, and provided rigorous testing of strips from 0.025 inch to 0.250 inch in thickness. "Delta Metals knows the importance of flatness to its customers and wanted a way to verify the quality of its output," explains Cox.
Darren Aghabeg at Delta Metals confirms that the testing and the resulting equipment have been valuable. "Flat Trak is a useful tool for getting steel flatter, a time-saving tool for revealing problems if they occur and a terrific sales tool that boosts customers' confidence that they are getting the level of quality they request," he says.
"We post the stickers that come from the system printer on our tags to certify the flatness of our finished goods," says Aghabeg. Printouts are filed with finished production paperwork so if a customer ever has a question, the record can be checked. "With our levelers, it doesn't seem to matter what the steel looks like; whatever goes in comes out flat.
"Flat Trak allows us to show customers just how good the product is," adds Aghabeg. "Our operators know how to set up a leveler just by looking at the steel, but with Flat Trak they can actually get a visual map of the strips on the graphic interface, so they have an added way to fine tune settings."
Bradbury also has released a stand-alone system that will work on any cut-to-length line in the world. "Our stand-alone system can be positioned next to any existing leveler control to assist operators with real-time strip information so that they can make educated adjustments and produce consistent results from their equipment," says Cox. The same three-light system and label printer will be included with the stand-alone unit. Strip marking capabilities will be offered as an option.
"With Flat Trak, we are taking leveling to the next level and bringing flatness standards in line with industry capabilities," adds Cox.MM
From the January 2006 issue of Modern Metals.