A POWERFULPARTNERSHIPHow metal products play an important role

in advanced energy technologies

COIL PROCESSINGWith RDI’s fast, coil-fedfiber laser, OEM cutswaste and changeoverwhile tripling productiontime on thin-gauge steel

coilprocessing

BY NICK WRIGHT

In his novel “The Lord of the Flies,”William Golding wrote that the great-est ideas are the simplest. When itcomes to coil processing lines, whose

functionality depends on layers of complexprocesses working synchronistically, thebenefits of removing inefficiencies radiatesbeyond the coil’s edge. Fiber laser blank-ing is among coil processing developmentsthat are making manufacturing simple bycombining operations and scuttling mul-tiple processes.

The RDI Group, based in Itasca, Illinois,first brought its coil-fed fiber laser blankingsystem to market in 2011, under the nameRDI Laser Blanking Systems and in the lasttwo years the technology has been showingup in more shops. For most RDI customers,the big attraction is improved productiontime by bundling separate cutting orpunching processes into one. That was akey selling point for one of its customers, amanufacturer of hollow metal doors. Thecompany sourced The RDI Group in 2012after looking for technology that would en-hance its coil processing and ultimately give

a competitive edge.Initially, the manufacturer’s team waslooking at coil-fed hard tool punchinglines because they offered desirable cycletimes. After contacting The RDI Groupand having the engineers there review theparts, RDI estimated cycle times withinthe manufacturer’s targets. “The major advantage to purchasing alaser as opposed to hard tooling was theflexibility the laser provided,” says the com-pany’s manager of manufacturingtechnology. “We can change productgeometry on the fly without tool changes,and we retain the flexibility to makechanges as our product and industryevolves.” By merging coil feeding technol-ogy with fiber laser cutting, The RDIGroup has dialed in an efficient, continu-ous parts production feed that boostsproductivity, and provides secondary ben-efits as well.

Welcome savingsAt the door manufacturer, its previous coilprocessing required several steps. First, itwould bring in stock slit coils of variouswidths and run them on a cut-to-lengthline in large batches to produce steel

Modern Metals® May 2014

Closing the door on scrap

For OEMs, processing coils insteadof sheet metal blanks reducescosts, material handling and scrapat the fiber laser cutting process.

With RDI’s fast, coil-fed fiber laser, OEM cuts waste and changeover while triplingproduction time on thin-gauge steel

sheets. Then, the sheets would be trans-ferred to either an NC turret punch press,or a bed-style CO2 laser to cut holes andgeometries. The stacks of parts would nextbe transferred to forming lines for finishing.Many of those steps are now achieved inone fell swoop.With the coil-fed fiber laser line, the man-ufacturer can directly load its slit coils andmake parts that are ready for forming in onesimple step. This cuts work in process in-ventory and unites multiple processes intoone. The company cuts cold rolled 1008steel as well as galvanneal in the 14 to 18gauge (0.048 to 0.075 inch) range. The fiber laser provides cost-per-partsavings, as well. Cutting speeds for thinnermaterials are significantly faster whenusing a fiber laser compared to a conven-tional CO2. As material gets thicker, thecutting speeds approach those of CO2lasers. The door manufacturer cuts thinsteel, which allows it to take advantage ofthe difference in cutting speed. “With the fiber laser technology, we arecutting at three times the speed we cutwith on our late model CO2 lasers,” saysthe company’s manager of manufacturingtechnology. “And by taking the material di-

rectly from a coil, we are able to really cap-italize on that increase in productivity.”Steve Stultz, sales manager at The RDIGroup, explains that the OEM customermakes door frames composed of threepieces—the hinge, latch and header. “Whatthey did before was cut the length of theblanks, so there would be 150 pieces of thehinge side, and then take them to a roboti-cally fed flatbed laser,” he says. Then, robotswould take each blank, cut the features, takeit out and restack it. Next, the parts wouldgo to a roll forming line or press brake, andlastly operators eventually matched up thethree separate parts for welding.Now, the coil is fed, laser cut and rollformed, rendering finished parts. “We do itas a system,” Stultz explains. “They can cutthe hinge side, header and latch, one afteranother, without restacking it and cutting itagain, so we eliminated the workingprocess and gave them sorted parts readyfor welding from production.”In most cases, like cutting stainless andaluminum, nitrogen gas is specified to

maximize fiber laser potential, althoughshop air works for some steel where oxida-tion isn’t a big concern. The doormanufacturer cuts with shop air boosted toan elevated pressure. “We don’t tend tohave issues with our finishing processesdue to oxide layers,” the customer says.

Servo gainsThere is usually some variation among thecapabilities of machinery equipped withfiber laser technology as far as cutting speedgoes. Even comparing laser OEMs thathave the same IPG laser source, whichRDI’s blanking laser uses, the speed andrigidity of the cutting head is important tothe quality and speed of the cut.Coil-fed laser blanking has existed for atleast a decade, but The RDI Group is one ofthe first to appropriate a fiber laser for coil-fed blanking in the U.S., says Stultz. “Wecompletely redesigned how it works in orderfor it to convey the speed of a fiber laser.”It’s not only the integration of fiber laserswith coil-fed cutting that separates The

Modern Metals® May 2014

coilprocessing

The laser has an “X prime” axis, which gives the laser 4 additional inchesof travel, allowing cutting of anything 4 inches or smaller without movingthe sheet.

Modern Metals® May 2014

coilprocessing

RDI Group’s technology from other coilprocessing advancements, but the controlsbehind it. Stultz says there are other com-panies who make versions of coil-fed laserblanking systems, but only this patentedprocess uses a high-speed servo feed in con-junction with the laser. The servo roll feedmoves sheet in the X axis, while the laserdarts across the Y axis powered by a linearmotor. The RDI Group also added an “Xprime” axis, which gives the laser an addi-tional 4 inches of travel, “soanything 4 inches and smallerwe cut withoutmoving the sheet,”says Stultz. “By coordi-nating the three axes wecan cut faster than if we just usedthe traditional X and Y axis.”Combining a quick-reacting servo feedcontroller with coil feeding reduces scrap,augments material utilization and requiresless storage space of material. However, be-cause the blank is a fed coil, it needs to bestraightened or flattened, depending on theoperation. The door manufacturer in thiscase uses RDI’s precision straightener to re-move moderate coil set, though the widthof its coils does not require a leveler. Thestraightener is a small diameter roll straight-ener with backup rolls—more thansufficient to flatten the material. The alternative is a roll leveler, allowingusers to bend rolls left or right to remove de-fects. The RDI Group’s 1-meter-widesystems come with a precision straightener,while the 1.5- and 2-meter systems comewith a leveler.

Scrap reductionFor any company using a coil-fed laser cut-ting system, operators are essentially dealingwith a 2,000-foot-long nest. Because of thecontinuous nesting as coil is fed, The RDIGroup’s line reduces scrap at the end of thesheet (RDI specifies SigmaNest for its nest-ing software). Only so many parts can becut from a sheet, which leaves scrap as aninevitability. With coil, that scrap is miti-gated by about 10 percent. The scrap thatdoes get produced drops below through aservo-adjustable chute to a conveyor, leav-ing operators to attend to other tasks. Thatfact alone isn’t the only opportunity for sav-ings—it’s also cheaper to buy coil than

sheet. Changeover time, as a result, getswhittled down. “Even the fastest systems take a goodminute or more to change sheet over andcut again,” explains Stultz. “During thattime, our machine is still making parts,making it 50 percent faster than a tradi-tional sheet-fed system.” The door manufacturer reduced itsshifts from three to one and cut its scraprate. “It’s amazing what it did for them.That’s where you save the money with acoil-fed type laser,” Stultz adds. This type of line is best suited for

OEM-level manufacturers, with theadded benefit of only needing one opera-tor to run the entire system. Smaller jobshops and fabricators may still be betteroff with a sheet cutting system. Nonethe-less, when an OEM can merge multiplesteps with a newer technology, resultingin reduced scrap, material costs andhours worked, companies of all sizesshould take notice. �

The RDI Group, Itasca, Illinois, 630/773-4900, www.therdigroup.com.

Reprinted from Modern Metals® May 2014 • Copyright Trend Publishing Inc.

EVEN THE FASTEST SYSTEMS TAKE A GOOD MINUTEOR MORE TO CHANGE SHEET OVER AND CUT AGAIN.DURING THAT TIME, OUR MACHINE IS STILL MAKINGPARTS, MAKING IT 50 PERCENT FASTER THAN ATRADITIONAL SHEET-FED SYSTEM.

STEVE STULTZ, THE RDI GROUP

The RDI Group’s 1.5- and 2-meterwide coil systems come with aprecision leveler, shown here. One-meter-wide systems comewith a straightener.