Laser Cutting and Welding Technologies Advance - Society of ...

Laser Cutting and WeldingPhoto courtesy Trumpf Inc.Laser metal deposition process from Trumpf enables manufacturers to coat a durable surface onto metal partsfor corrosion resistance in harsh environments.Laser Cutting and WeldingTechnologies AdvanceNew techniques in laser cutting and weldingare opening doors in automotive and medicalmanufacturing applicationsPatrick WaurzyniakSenior EditorLaser technologies for cutting and weldingparts have been steadily refined since thelaser was invented some 50 years ago. Today,laser technology is easily used to quickly cut2-D or 3-D sheetmetal parts and to makehigh-quality welds. The flexibility of lasers hasled to adoption of robotic laser processing and five-axislaser cutting and welding in many areas, including cuttingthe newer high-strength steels in today’s automobilesand cutting and welding processes used in medicaldevice manufacturing.August 2011 | www.sme.org/manufacturingengineering 69

Laser Cutting and WeldingPhoto courtesy ABB RoboticsAdvances in lasers’ power, improved cutting speeds andedge quality, and lower operating costs have opened moreavenues for use of the technology. Gains in power, speed, andlaser beam quality during the past decade have helped manufacturersuse the systems in more areas, and better beamquality also reduces the need for secondary operations.Robotic laser processing with an ABB IRB 2400 robot and anIPG fiber laser offers speed and flexibility cutting a Tier Onesupplier’s boron-alloyed B-pillar automotive body component.Newer applications include more widespread use oflasers to cut the automotive industry’s latest hot-stamped,lightweight, ultra-high-strength steels (UHSS) that are beingused to make smaller, more fuel-efficient automobilesmuch stronger and safer than earlier models. Lasers canefficiently cut the hot-stamped steels and hydroformedparts that make up some of automotive’s strongest sheetmetalcomponents, such as car and truck A and B-pillars,as well as dashboard structures.Robotic laser processing on UHSS components has madeinroads in recent years, as has five-axis laser cutting of thesecritical components, as automakers seek more efficient methodsof handling newer steels that are too difficult to processwith typical stamping operations. “For us right now, the biggrowth is in automotive components,” notes Joe Campbell,vice president, Robot Products Group, ABB Robotics(Auburn Hills, MI). “That’s where all the market forces comeinto play—brutal competition, they’re moving to high-tensilestrength steel, and they have to go deal with the manufacturingprocess. We have a couple customers who are starting tofigure out that it [robotic lasers] could be used as an offensivetool. It’s not just, ‘I’ve got to do this because the guy sent methe spec on the material.’ They’re starting to figure out that itmay be a better manufacturing process.”Using robotics for laser processing can offer manufacturersadvantages over much more expensive five-axis lasersystems including lower costs and greater flexibility, accordingto Campbell. “There’s a convergence of multiple technologiesthat finally gets to critical mass. The automotive manufacturingbusiness is kind of brutal—it’s cost per part. They’re reallynot interested in how sexy your stuff is. But there’s been acombination of improvements, in the lasers themselves, thedelivery vehicles, the heads, the robots, the software—everything’sbeen incrementally improving to the point where we’vegot a very nice package, which has fueled some growth. Andthen there’s been a pretty significant change in a lot of thematerial or the metallurgy going into vehicle components inorder to get weight out. These lightweight, high-strength steelsare great, but they’re hell on die sets.”If automotive manufacturers had a choice, they wouldstamp their parts, contends Doug Hixon, ABB robotic lasercutting and welding specialist. “If the Tier Ones could trim andpierce features within their current forming process withoutaccelerated die wear, they would do it in a heartbeat, but currentlylaser cutting is their best option,” he adds.Automakers need to quickly process higher volumes ofhot-stamped parts, leading some suppliers of five-axis lasersystems to introduce systems specifically tailored for lasercutting of UHSS auto parts. Laser systems builder Trumpf Inc.(Farmington, CT) recently introduced its new TruLaser Cell8030 five-axis laser cutting system, and in May, the companyannounced an order for 50 of the TruDisk fiber-guided lasermachines to be delivered to Volkswagen AG for use in VW’sWolfsburg, Germany, headquarters, and at other sites.“What the automotive industry is faced with is that thecustomers are demanding smaller, lighter, and safer vehicleswith better fuel mileage, and one way to accomplish that task70 www.sme.org/manufacturingengineering | August 2011

is by the use of ultra-high-strength steels,” states Frank Geyer,product manager, five-axis laser systems, Trumpf Inc. (Farmington,CT), “because with conventional steel you would haveto use more material, making small cars heavier and slower.“In the hot-forming process, a specialultra-high-strength steel is used for theblanks; those get heated up to about900°C, formed, and then quenchedwhile in the die,” says Geyer. “What thatdoes is it arranges the grain structureand makes the part extremely hard andstiff. The resulting sheetmetal parts areof very high strength, and that leads toa dilemma—because of their properties,they cannot just be blanked or cutconventionally. Due to their martensiticstructure, the ultra-high-strength steelsare so hard that a conventional blankingdie wears out after about 1000 hits, makingthe process uneconomical.”In comes the laser, which is cuttingwith light, with no wear on the tool itself,Geyer notes. Over the years, lasers havesignificantly improved in power andbeam quality, he adds. “The combinationof these high-power lasers with highbeam quality and high-performancefive-axis systems has evolved into a solutionwith the TruLaser Cell 8030 that wasdeveloped for the hot-stamping business.Typical customers are Tier One suppliersthat provide the stamped panels oreven the completely welded bodies to theautomotive manufacturers.”The automotive market requires veryhigh productivity, output, and flexibility,says Geyer, adding that here the fullyprogrammable five-axis laser systemshave many advantages over conventionalsystems. “You don’t have degradationof the tool, for example, like with conventionaldie blanking—those tools wearout and your product changes, and withthe laser it does not. The cutting processis very consistent and efficient. Assmall cars have a greater percentage of the ultra-high-strengthsteels than they used to have, they have an increased volumeof parts per vehicle, and so high productivity is crucial to helpingmeet the ever-increasing demands of customers.August 2011 | www.sme.org/manufacturingengineering 71

Laser Cutting and Welding“High productivity also usually brings down the costs of the operation. That’s wherethe TruLaser Cell 8030 equipped with the TruDisk, a solid-state laser with a fiberdeliveredbeam, comes in play. It has a small footprint, is very fast, and it consumessignificantly less energy than conventional systems, compared to CO 2systems.”The Trumpf TruLaser Cell 8030 system comes standard with a 3-kW laser resonator,with a 4-kW resonator available as an option. Cutting UHSS materials doesn’tnecessarily require higher-power lasers, Geyer notes. “Typically, the thickness ofthose materials rarely exceed 2–2.5 mm, so the materials themselves do not requirea higher-power laser, and the complexity of the 3-D component limits the cuttingspeed. You can’t just go with full speed, like with flat-sheet cutting,” he states. “Youhave process speed limitations when cutting complex 3-D geometries. A 3-kW laseris efficient enough to cut about 90-95% of the parts. If the part has a very simplegeometry, a 4-kW laser can give you a little more of a speed advantage. Going for a5 or a 6-kW laser is not going to give you any advantage, because you’re simply notreaching a higher processing speed; the laser would be just too powerful for whatyou can do.”“These lightweight, high-strength steelsare great, but they’re hell on die sets.”For welding, Trumpf also offers its laser metal deposition (LMD) process thatwelds powder on a metal surface for components used in harsh environments.“These applications are where you need to tailor the surface of a part, specificallyfor corrosion or abrasion resistance, and include industries such as the petrochemicaland offshore industries, and the turbo engine industry or agricultural. These arethe types of companies that make components and use components that see a lotof abrasion and corrosion,” notes Dave Locke, LMD applications manager. “It’s atechnology that’s been around a long time, but with the advances that we’ve seenin the last handful of years, specifically the fiber-delivered lasers and higher powers,it’s suddenly made it much more practical to do a lot of powder deposition in applicationsthat have always been there, but in many cases, haven’t been economical.”Hot-stamping of boron steels began in Europe, where it was introduced in the1980s by European automakers initially for production of side-impact beams, notesTerry L. VanderWert, president of Prima Power Laserdyne (Champlin, MN). The processhas since gained momentum in other regions, including North America. Primarecently announced it has expanded its Minnesota facility to handle final assembly,test, and customer installations of its Rapido Evoluzione five-axis system that canquickly trim and cut features in hot-stamped automotive components. With its fiberlaser, the system offers users rapid traverse rates of 175 m/min, and is said to becapable of cutting and trimming an automotive B-pillar in under 50 sec.“The steel blanks are heated to 900°C or higher, formed at near this temperature,and then cooled in the die. The high hardness of the formed parts makes traditionalmetal trimming or punching impractical,” VanderWert says. “The five-axis laser is thetool of choice for that application, because of its speed and flexibility, because there arerelatively high volumes because of the automotive levels of production.August 2011 | www.sme.org/manufacturingengineering 73

Laser Cutting and WeldingPhoto courtesy Cincinnati Inc.Powerful lasers like this five-axis CL-850 laser from CincinnatiInc. easily pierce holes in flat-sheet metalcutting applications.“North American manufacturers were slow to adopthot-stamping, because we had larger cars and fuel wasn’tthat expensive relatively,” he adds, “and as soon as thefocus turned to more energy-efficient yet safe automobiles,they found the need to adopt the hot-forming process.Within the last couple years, the rate at which hot-formingis being used has clearly accelerated. Today, you will findhot-stamped parts in virtually every car and truck manufacturedworldwide.”More use of fiber lasers is an ongoing trend in the laserindustry, VanderWert notes, and the current Rapido systemwas designed around this application, both with its size andthe performance of the cutting speed. The machine haslonger strokes (4080 × 1520 × 765 mm) and can handlea wider size range of components. “We use both CO 2andfiber lasers,” says VanderWert, “but I would say the trend istoward fiber lasers. They’re faster. It’s all about cycle time,and ultimately about part cost. The goal in many of theselarge components is for less than oneminutecycle time.”Fiber lasers continue to gain convertsover CO 2lasers due to fiber lasers’inherent advantages, notes Rick Neffof laser systems developer CincinnatiInc. (Harrison, OH). Neff, a memberof SME’s Industrial Laser Community(ILC), recently moderated an SMEwebinar, “Industrial Laser Cutting 101,”covering the technical advantages ofdifferent laser-cutting technologies.Fiber lasers have a beam wavelengthof about 1.0 micron so they can bedelivered to the cutting head with a thinglass fiber, Neff notes, while CO 2lasersbounce the beam off mirrors and usebellows that expand and contract tocontain and deliver their beam.Beam delivery on lasers has improved,Neff adds. “The focusing lensesare different with CO 2and fiber lasers,”he says. “There are newer compactheads that need to be small as they’reoften put on the end of a robot.”For thicker materials, the choiceoften can be CO 2lasers that can easily74 www.sme.org/manufacturingengineering | August 2011

Laser Cutting and Weldingcut through thicker, harder metals. “CO 2lasers cut all types ofmaterials,” Neff says. “Fiber has a little trouble with translucentmaterials. Fiber can cut thin copper but for something like a 0.5"[12.7-mm] bus bar, waterjet would be better be a better choice.A 4-kW CO 2can cut 1" [25.4-mm] mild steel with ease.”A key advantage of fiber lasers is the technology’swall-plug efficiency—it’s simply more cost-effective to runthan many other laser types. “Fiber laser can be deliveredin a smaller fiber, so it provides a better beam for cuttingthan other types of fiber-delivered lasers,” Neff adds.“Fiber and direct diode are much more efficient than CO 2in operating costs. While the fiber resonator requires nomaintenance, the recommended maintenance is about every2000 hours on a fiber cutting system. The time to domaintenance is maybe half that of C0 2lasers.”Costs per 100" (0.25 m) of cutting with a C0 2can runabout six cents per cut whereas costs to run fiber lasers areabout two cents per 100" cut, he adds.Improvements in both lasers and robotics has enabled greatprogress in laser cutting and welding over the last few decades,observes Michael Sharpe, materials joining engineering, FanucRobotics America Corp. (Rochester Hills, MI). Fanuc Roboticsdeveloped the first integrated CO 2laser robot, the L-100, backin the early 1980s, Sharpe notes. “It was unique in its day,”Sharpe says. “That was back when we were GMF Robotics.The first L-100 series was CO 2-based, so beam-delivery systemswere integrated into the robot. It was designed basicallyfor tailoring of materials, either tailoring and/or welding, and itwas primarily for automotive OEMs and their suppliers.“The industry kind of softened for a number of years,and then hydroforming came along, in about the late '90s,”Sharpe recalls, “and part of the problem with hydroforming isbecause you blow the tube up like a balloon you only have somany surfaces that can be punched, so it required a machiningprocess. Laser machining or cutting in this case was themost viable due to the throughput.”76 www.sme.org/manufacturingengineering | August 2011

Automakers started using improved steels for crash androllover protection in about 2002, as the quickest way tochange the vehicle’s design was to change the material,Sharpe says. “A lot of martensitic or hot-stamped type materialscame onto the market with dualphase,there are many different tradenames,” he recalls. “But the long andshort of it is they’re very difficult to trimin a stamping die, or a trim die. They’revery harsh on tooling because they’re sohard, and that necessitated the need forrobotics to do that trimming.“Throughout the industry, it’s beendriven primarily by automotive, bythose demands for that requirement,”he adds. “Now all along, you’ve hadimprovements in laser technology. Ifyou look at the latest improvements insolid-state designs and fiber deliveries,they basically brought the costfactor down. And by bringing thecost-quality factor down, now I cando more applications, things such asrobotic remote welding.”For laser cutting and for weldingapplications, laser developer MitsubishiLaser/MC Machinery Systems Inc.(Wood Dale, IL) offers a wide rangeof systems, including the company’smost popular 2-D flatsheet cutter, theLVPlusII, notes Jeff Hahn, Mitsubishinational product manager. That systemoffers a 4.5-kW laser resonator asstandard, and the Mitsubishi NX systemis available with a 6-kW resonator forhigher-power applications.“In welding, we only go up to a 4 kW,and we have two new five-axis machinescoming out,” Hahn notes. “For2-D cutting, the big interest right now isnitrogen cutting mild steel, that way a lotof people are doing a lot of work for theKubotas and Caterpillars, and they don’twant oxidation on the cut edge, becausewhen they paint it, it’ll chip off, and itcan be awkward to remove it. So right off the machine, youcan get a finished part by cutting the mild steel with nitrogen,with no oxidation layer or coating onto the cut edge. If you useoxygen, you’re going to get an oxidized edge. If you use nitro-August 2011 | www.sme.org/manufacturingengineering 77

Laser Cutting and Weldinggen, you don’t get that. You get a clean, weldable, paintableedge right from the machine.”With the new five-axis machines, Mitsubishi is implementinga full-rotary axis for six-axis, simultaneous movement,Hahn adds, and the NX laser systems are also offering thenew LC30 Mitsubishi control. “We use it on our EDMs andwaterjet, it’s going across our product line and we’re migratingmost of the machine tools towards it now,” Hahn says of thecontrol. “Everything’s faster on it, and it’s an NC with PC, sowe use the Windows GUI interface on it, and you can connectto hard drives and hook the machine up as a node on a LANvery easily.”In welding, the LC30 also will help users by offering moreof an intelligent control, as far as adapting what’s calledDRC technology to the parts, notes Hank White, Mitsubishiwelding specialist. “DROSS Reduction Control [DRC] helpswith most of those parts on the five axis that are thinner,”Hahn adds. “DROSS, which is what the Japanese call it, iskind of like a hybrid word meaning burr on the bottom; whenyou slow down, you can get a burr on the bottom, and thiseliminates that.”The new controller also helps with slope control, Hahnadds, for welding applications. “What you have to do withwelding is ramp power up gradually to full power, thenweld, and then ramp it down when you come to the end ofthe weld,” he says. “This offers a lot better control for thatbecause the machine will do that on its own, once you set theparameters, so it’s like a TIG welder.”Precision cutting and welding with lasers is a focus forMiyachi Unitek Corp. (Monrovia, CA), as medical-devicemanufacturers demand smaller, more reliable, faster, andmore cost-effective solutions. The company has recentlyintroduced new cutting solutions and is broadening itsaccess to different industries, notes Mark Rodighiero, thecompany’s vice president, systems, technology, and productdevelopment.78 www.sme.org/manufacturingengineering | August 2011

“We’re broadening our access to different industries,”notes Rodighiero. “Another area is corrosion-resistancemarking for medical devices and also for aerospace devices.There are a lot of requirements for medical to identify partswith unique identifiers or serial numbers,especially as the FDA directive onmedical-device UDI marking is aboutto be released. So we’re branching outfrom welding into other areas, developingapplications and machine capabilitiesand going after commerciallyvaluable applications.definitely a movement in the fine laser-cutting industry frompulsed YAG lasers to fiber lasers for those reasons.”In metalcutting, the wavelength is going to be about 1 µmand remain that way, according to Shannon. “In the expanding“To weld a smallconductive part isreally, really difficult.”There is a movement from traditionalcutting technology toward newerlaser cutting technology in a numberof areas, notes Geoff Shannon, lasertechnology manager, Miyachi Unitek.“There’s a migration of looking at lasercutting for tube cutting, for three-axisand five-axis cutting, to look at replacingexisting technology for reasons ofquality, throughput, and cost,” he adds.“The applications that spring to mindare cutting single-sided features, suchas windows or channels on thin-wallthicknesstubes, which is a very slowprocess for traditional techniques, suchas sinker EDM.”The laser industry is rapidly movingtoward fiber lasers from older processesfor a variety of reasons, Shannon says.“In terms of technology migration inthe laser industry, there is a movementfrom the old Nd:YAG technology to thefiber-based cutting technology for basicallyreasons of cut resolution, controlof the laser pulse, speed of cutting,and just the economics of the equipmentas well,” Shannon states. “There’sAugust 2011 | www.sme.org/manufacturingengineering 79

Laser Cutting and Weldingfield of micromachining, you will see a shift to different wavelengths,just because you have advantages in the resolution ofwhat you can do with those different wavelengths,” he explains.“Essentially, as you decrease the wavelength, the spot size thatweld perhaps much smaller parts with finer details. Thepulsed YAG green laser is really a line to conductive materials.To weld a small conductive part is really, really difficult, andso the green laser’s perfectly tuned to doing that because thegreen gives you a real advantage in absorption over the 1-µmwavelength that is normally used with either the pulsed YAGor the fiber. As the miniaturization is kind of accelerated, wefeel the green laser will be a great solution for electrical connections,terminal connections, in conductive materials.”Many implantable medical devices have electronics beingdriven by a battery, he points out. “You have to distribute thatpower in the battery by bus bars or internal conductors, andit’s those welds that we’re talking about,” Shannon notes.“It’s the interconnects of the power source with the elementswith that device that need that power. And all these devices,they’re only going to get smaller, and they’re only going to getmore power so they can have longer lifetimes, and we’re talkingabout a joining process which gives you greater reliabilityand longevity, and also the opportunity to miniaturize yourterminal to less than it is right now.” MEWant More Information?Photo courtesy Lincoln Electric.Robotics manufacturer Fanuc Robotics offers laser weldingrobots like this hybrid laser/arc-welding system through its roboticintegrators and laser partners including Lincoln Electric.you can produce also decreases—it gives you increased resolution,and also it gives you increased pulse control over how thelaser affects the material, so your thermal input into the materialgoes down. Thermal management in small parts is obviouslyextremely important, so there may be some advantages in thoseparticular applications where you can look to different wavelengths,especially for nonmetals. When you have to optimizeabsorption in a nonmetal, particularly a plastic, using thoseshorter wavelengths normally has some advantages for you.”Micro welding in medical still uses traditional pulsed YAG,but users are looking toward fiber lasers, he adds. “Althoughmany applications remain suited to the pulsed YAG laser,there’s a resolution advantage of the fiber laser in that it canABB Robotics North AmericaPh: 248-391-9000Web site: www.abb.com/roboticsCincinnati Inc.Ph: 513-367-7100Web site: www.e-ci.comFanuc Robotics America Corp.Ph: 800-iQ-ROBOTWeb site: www.fanucrobotics.comMitsubishi Laser/MC Machinery Systems Inc.Ph: 630-860-7824www.mitsubishi-world.comMiyachi Unitek Corp.Ph: 626-303-5676www.muc.miyachi.comPrima North America Inc.Ph: 413-598-5200www.prima-na.comTrumpf Inc.Ph: 860-255-6000www.trumpf.com80 www.sme.org/manufacturingengineering | August 2011