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Submitted by: Hanklp Icharo
Sheet steel fabricators were working to solve problems with steel surface quality when they unearthed a novel answer: a brushed surface that resists rusting and laser or plasma cuts faster than ordinary hot roll or cold roll.
Bryan Hawkins, owner of Hawkeye Industries, sheet metal fabrication firm in the Southeast was on the hunt for a sheet steel offering a better paint finish for the precision fabricated steel parts this contract fabrication company produces. The odd thing is Hawkeye doesn’t paint the parts it makes – it outsources the painting, plating or other finish. Even so, the parts Hawkeye fabricates for its customers must meet its high standards so Hawkins worked with his contract painter, looking for ways to reach a more consistent finish without the costs of an expanded pre-paint process or, in the worst case, rework.
Hawkeye engaged their steel suppliers in the effort, motivating them to recommend a flat rolled sheet steel with surface finish that might do the job. One supplier brought in sample sheets of a completely new hot rolled product that had just come to the market. Its name was SCS, for Smooth Clean Surface – a process that brushes the surface of common hot band, leaving it uniquely clean and resistant to rusting without the need for any coating or protective oil.
Hawkeye’s painting subcontractor perfomed trials on multiple samples made from sheets of SCS and attained excellent results – consistent, cosmetically superior surface with good adhesion. With further trials, the painter found they could use a leaned out wash cycle since, unlike the hot rolled pickled and oiled (HRPO) steel Hawkeye most commonly used, there was no oil to be removed from SCS.
Mission accomplished. Hawkins was pleased and asked his steel buyer to start replacing some HRPO purchases with SCS. He didn’t give this new ‘clean steel’ much more thought until a week or so later when one of his best laser operators came into his office and said, “Bryan, come out to the shop. You’ve got to see this.”
Hawkins walked out to his TRUMPF 3040 laser cell to see it running a tightly nested collection of parts Hawkeye ran frequently. This time, the laser was processing an SCS steel sheet. “Look at the job time,” the operator said. Hawkins looked at the control, blinked his eyes, then looked again. The sheet had run 20% faster than their standard for that job.
The operator had been running more SCS and noticed how the laser head seemed to glide across the clean, consistent surface. He decided to “tune” the laser a bit and found he could cut the SCS faster with no loss of cut quality.
Coincidence? Not at Hawkeye Industries, a company on the leading edge of laser technology. In addition to running the first TRUMPF 3040 cell in the US, Hawkeye had also installed one of the first TRUMPF TC6000L Punch/Laser Combination cells. Hawkins is a recognized experts on laser technology and productivity.
They put that expertise to work, trying different laser settings that had been established for cutting HRPO sheet meal to optimize them for cutting SCS. Hawkins recalls. “New lasers like ours are fast to start with, but SCS sheets give us another 15% to 25% speed advantage over HRPO sheets.
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Steel fabricators became interested in SCS to inhibit rusting with no need for protective oil. That not only gives SCS-treated steel a longer ‘shelf life’, it also reduces the need to clean the steel prior to painting. SCS savings is what attracted manufacturers to SCS.
As the number of SCS users grew, stories about another equally remarkable property of SCS started coming back to TMW: SCS-brushed steel sheets or plate laser and plasma cut faster than hot roll black or HRPO sheets the same result that Hawkeye Industries had validated.
TMW was referred to Precision Laser Manufacturing. PLM is a contract laser processor offering laser cutting, welding, engraving and heat treating to the con-ag equipment, automotive, medical, food processing and defense industries. Todd Berry, owner of PLM explains, “Laser work is all we do, so we pride ourselves on our ability to ‘tune’ our lasers for different materials. When we were asked if we could run some comparisons of lasering SCS, HRPO and untreated hot roll, I was interested because they were all the same thickness and comparable chemistries. The only difference was the surface preparation.”
PLM’s laser operator made a few benchmark cuts then started to tune their laser for the different materials. Berry explained, “We alternately varied power, nozzle diameter, focal length and assist gas pressure while slowly increasing travel speed. When we got to where the cut quality deteriorated, we’d make some adjustments to bring quality back in line, then gradually increase speed some more. It was an iterative process, but it didn’t take much time before we found what seemed to be an especially effective arrangement of settings.”
“The SCS steel surface definitely cuts faster, especially at the thinner gauges. That’s completely logical, because what’s different about the SCS is its surface. In thinner sheets, that surface effect is magnified relative to thick sheets.”
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Another sheet metal fabricator searching for a solution to steel surface quality issues decided to try SCS. The difference in this case was the material was in the form of tubular steel, not flat sheets.
Industrial Laser Solutions (ILS), of Tie Down Engineering of Atlanta operates three advanced laser tube cutting cells, but sometimes faced problems with rust developing on the hot roll black and HRPO welded tubular steel they were buying. Those rusted tubes were for cleaning – a process that added cost and also added cycle time. ILS did not want to be in the secondary steel recovery business any longer.
Nancy Shadrix, the steel purchasing manager for ILS, proposed running a limited trial of SCS-treated hot roll tubular steel. The trial was a success and Tie Down converted over its tubular steel orders to SCS. This not only eliminated the rust problem, but allowed Tie Down to consolidate the separate hot rolled black and HRPO purchases into a single SCS purchase.
Chuck MacKarvich, founder and President of Tie Down Engineering, next wanted to replace all his hot rolled sheet steel with SCS steel for the price savings. But he needed to be certain it would present no issues in other areas, as Tie Down /ILS also performs several other fabrication operations in addition to lasering. Sloan MacKarvich, Chuck’s son and a leader of the ILS enterprise, oversaw the use of SCS material through those fabrication processes and was pleased to see the material perform well across the board.
“We run four Mitsubishi ML 3015 SV flat bed lasers and, yes, we saw speed increases with the SCS-treated material. But we also get a cleaner cut, even at extremely tight tolerances with the SCS steel sheets.”
Sloan added, “With the cleanliness of the SCS surface finish we found our weld quality improved and our welding cells became more productive. Plus, our paint finish looks better on the SCS parts, so next we want to see if we can lean out our paint prep, as I’ve been told we should be able to.” ILS has switched over nearly all of their flat rolled steel purchases to SCS-treated steel.
Concludes MacKarvich. “Too often when you make a material change to try to fix a problem in one area, it introduces a different problem or limitation in another area, so you go on searching. This time, we not only solved the original problem, but found benefits in other sheet metal fabrication areas that we had not anticipated. It’s kinda like reaching down to pick up a crumpled dollar bill you see on the sidewalk and finding a five dollar bill folded inside it – a nice little bonus for your efforts.”
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