By Geoff Giordano
With photonics-driven manufacturing innovation becoming a hot topic in the nation’s capital, advanced laser applications — particularly in aerospace, automobiles, agriculture and energy production — are getting a bigger share of the spotlight.
From gas and steam turbines to pipelines and passenger jets, even underwater welding in nuclear reactors (see LAM 2013 wrap up story), current and next-generation lasers will bear more of the brunt of manufacturing, protecting and repairing vital components of all types and functions.
When Fraunhofer ILT won Aviation Week’s innovation award last year by producing an 80-blade BLISK (blade-integrated disk) in about two minutes per blade with laser additive manufacturing (AM), it provided a powerful example of potential manufacturing efficiencies.
“The difference in manufacturing time is a factor of roundabout 60: minutes instead of hours,” explains ILT’s Prof. Reinhart Poprawe, immediate past president of LIA. “An average-sized BLISK will take about 180 hours of milling. With laser additive manufacturing, we can make it in 180 minutes. Based on that, I am sure there are a lot of applications for complex components and products, which can be made more economically — and maybe more important, more ecologically — in the very near future.”
AEROSPACE AND AVIATION
At LIA’s second-annual Lasers for Manufacturing Event (LME®) in Schaumburg, IL, in October, past LIA President David Belforte provided a comprehensive survey of areas where lasers are going to influence manufacturing with their unique capabilities.
“There are 5,000 narrow-body jets being planned over the next 20 years to be built here in the United States,” he noted. Furthermore, with Airbus announcing it will double its operation in Alabama from $24 billion up to $50 billion, he enthused that aviation “is a terrific sector” for the laser industry.
Lasers are used to craft components throughout contemporary aircraft, from brackets and door hinges up to turbine engine components and fuel swirlers. The increasingly intricate operations lasers can perform often allow for redesigned parts that can dramatically reduce weight — up to 50 percent or more — by using less material and hence boosting energy efficiency.
In terms of turbine engines, Belforte noted that each of those 5,000 new jets will require two engines. “Every one of those engines has millions of holes drilled in it,” he said. “There are 1,100 companies in the United States involved in the aircraft turbine engine business; many are using industrial lasers.”
To be precise, “the typical jet engine has upwards of 3 million (transpiration cooling) holes that are percussion drilled,” noted Bill Shiner, vice president of industrial markets for IPG. “With fiber lasers, we’re getting better hole quality and better consistency, and we’re drilling up to 50 to 100 holes per second.”
But lasers are not limited to the insides of the plane. As the innovative wings and fuselage of the Boeing 787 Dreamliner illustrate, lasers are being asked to drill more than metals. “I never thought we would be cutting composites with lasers, but the fiber laser is doing an interesting application” in that area, Belforte noted. “With more and more composite materials being used in aircraft, it looks like a good growth market.”
Those composites can be cut “either by high-power multipass processing or by ultrashort laser pulses below the nanosecond regime,” Prof. Poprawe explained. “Both approaches are feasible, depending on the cut geometry: round holes or lines with multipass processing, and arbitrary shapes with ultrashort pulses.”
POWERING THE ENERGY INDUSTRY
“A lot happens in energy applications,” Prof. Poprawe asserted. “Practically all components and laser processes — drilling, cutting, welding, ablation and surface functionalization — are to be considered.” In battery production, for instance, high-speed cutting of multicoated electrodes is a promising application.
Lasers’ compactness, mobility and reliability are significant factors in their growing applicability. “We’re drilling down in oil wells up to 16 kilometers,” Shiner noted. “We have some of our lasers on vessels in the Gulf of Mexico welding components.”
More drilling rigs are going into operation every month, Belforte said. “Downhole drilling is a terrific opportunity, especially when you turn that angle and go 90 degrees to do that fracking operation. Many of those downhole operations use lasers one way or another, some of them to help fracture the rock.”
Laser metal deposition (LMD) has become indispensable to the oil and gas industry. “In the offshore area we have drilling components coated via laser metal deposition, especially oil drilling components,” said Juergen Metzger of TRUMPF. For example, “the tubes that are going down (and) connecting the driller with the base station. Then we have the so-called stabilizers that stabilize the tubes in the drilling hole, and they have really high requirements on wear resistance. They are made with laser cladding, with hard-facing coatings.”
Gas and steam turbines are another area where lasers can prove highly beneficial. The former “are expected to generate a quarter of all the power in the United States in the next five years,” Belforte said. “If you look at that engine… every one of those turbine blades, every one of those compressor sections, has got laser processing in it.”
“For the turbine business, about 90 percent is titanium-based alloys or nickel-based alloys,” Metzger said. “When we bring down material and build up a compressor blade by 2 or 3 millimeters, it’s very important that we are not bringing double the material that is needed. (We want) only about 20 percent more of what is needed on the sides” to reduce post-processing needs.
Today’s refined processes are a far cry from those about 20 years ago, recalled Rene Karel, president of Laser Welding Solutions (LWS) in Houston. “I came out of a conventional industry with conventional cladding techniques. We started noticing more of the laser-applied coating back in 1995, but it was very limited; it was mostly CO2 lasers. It’s come quite a way.” In the energy field, “there are constant innovations. Today you’re seeing all kinds of different (component) sizes, different geometries and different base materials.
“It’s constantly growing; it becomes a huge effort for most small companies to keep up with the different demands. You have to have an ongoing R&D project. It’s one of the things that allows you to enter other markets and market areas when you can develop something that is unique to that particular industry and it becomes a standard for a period of time until something else comes around that is a little better.”
For LWS, “we managed to get into the ID cladding better than most when we first started,” Karel said. But trial and error plays a significant role in adopting new laser applications. “Some of the components that were already out that were being developed by institutes. We looked at all of those and tested some of them, and none of them were that good. These things are designed basically in a laboratory: If they work, they’re deemed successful. But if you are in a manufacturing environment where it’s ongoing, 24/7, then flaws in the design will show up pretty fast. They become unreliable, they require a lot of maintenance — they require a lot of “tampering” to keep them going. We were able to come up with a design that was fairly robust and saved on excess powder. We hardly had to touch it very much at all; (the process) became a workhorse for us.”
Meanwhile, solar cells — requiring laser scribing of thin films and flexible substrates as well as the drilling of holes to improve energy conversion — are expected to undergo a resurgence this year, Belforte predicted. And, with 9,000 miles of pipeline out of a planned 20,000 miles under construction in the United States, hybrid laser arc welding will likely see increased usage. “A lot of those (projects) are considering or may even be using high-power lasers to weld the pipe together,” Belforte said.
GROWING BUSINESS IN AGRICULTURE
The agriculture industry was at once “spectacular” but a bit of a letdown for the laser industry last year, Belforte asserted. The heavy earth-moving and harvesting equipment at the core of food production requires “a lot of lasers for cutting, welding and cladding applications.”
“In earth-moving machinery, heavy-duty yet lightweight structures as well as surface-enhanced tools are applied,” Prof. Poprawe explained. “For the purpose of welding the structures, high-power and high beam quality lasers are needed. These include 10 to 40 kilowatt lasers with output close to the diffraction limit. Fiber lasers, disk lasers and CO2 lasers in that class are used. For cladding of components with wear-resistant coatings, metal layers or thick films, diode lasers are suited because the applications do not demand high beam quality. Thus, less costly lasers are used.”
Such cladding can double the life of particularly high-wear components, Metzger noted. Whereas more routine digging components can still be made with traditional methods, “we have a lot of parts that have to keep their geometry, like inside parts where other knives and blades are.” For example, he said, a shear bar produced with laser cladding “has to be quite straight (because) another knife blade is shearing along it.” Lasers’ low heat input is ideal for the necessary near net shape production.
While lasers are reducing the time required for post-processing, “more important is the reduction of the material needed,” Metzger said. “When you bring down material with a powder process, that has an efficiency of about 50 percent to 80 percent; we lose the powder. But with machining we also lose the very expensive material. That is why we try to be as close to net shape as possible. It’s less about the time reduced for machining than not losing so much material by bringing away material that is not needed.”
Marketwise, TRUMPF has seen growth in Europe, Russia and the US, Metzger said, but no clear picture has emerged in China yet.
Ultimately, “Precision and quality are the decisive factors for future products, where economical and ecological efficiency and lot-size independence are the main concerns,” Prof. Poprawe advised. “High-power ablation and additive manufacturing with high-power, ultrashort-pulse lasers and high beam quality diode lasers will make the difference over the next decades.”
He sees prices for these systems coming down “considerably,” particularly as the high-power diode lasers that directly or indirectly pump other lasers decline in cost.
In terms of increasing deposition rates, Metzger has a more conservative view in light of research indicating output approaching 20 to 30 kilograms an hour. At the moment, we can do about 3 to 4 kilograms an hour,” he said. “We are working on increasing the deposition rate per hour for rotary parts, but this is not anything that will explode. We will try to double it, maybe, but we will not try to make it 10 times higher.”
“I think the industry is narrowing it down to what works the best as far as cladding,” Karel said. “Deposition is a little bit of an issue when you get to really large parts and you want to try to do those as quickly as you can. Metallurgical data prevents you from going too far with that. There are limits.”
Wherever considerable material is milled from semi-finished products, “additive manufacturing will be the choice of the future,” Prof. Poprawe asserts, being less expensive, less time-consuming and using less material. Whether it will be preferable for a job shop to provide or treat parts, or for the end user to install its own equipment, will depend on the application. “We have exactly the same situation today in laser cutting, where the industry operates at a balanced point of job shops running 24/7 at minimum cost vs. proprietary processes at the end user.”
LIA’s industry-leading conferences and workshops — ICALEO®, the Laser Additive Manufacturing (LAM®) Workshop and the Lasers for Manufacturing Event (LME®) — keep users up to date on cutting-edge research and applications. To register to attend, visit www.lia.org/conferences.