The new process, which results from more than two years of collaboration between the two companies, uses lasers to remove sections of damaged material, while leaving intact the remaining healthy fibers and resin. The technique does not apply force or vibration to the structure, so it does not affect the structure's overall strength or integrity. After the laser treatment, the area where damaged material has been removed is left clean and ready for repair. This is done with a replacement patch, which is cured in place using a localized heating mat.
SCLR Lasertechnik specializes in using lasers to selectively remove coatings. The company performs surface preparation of machined parts for painting or gluing, as well as surface activation of carbon fiber-reinforced plastic and glass fiber-reinforced plastic composites, and removing paint in both types of composites. (Watch videos showing SCLR's surface preparation and paint removal of composite parts here.)
In the statement, John Cornforth, head of technology at GKN Aerospace, says:
With the first installation of this prototype equipment we are now commencing work on extending the ability of this new process to handle various shapes and sizes of structure. We believe this process has enormous potential; composite materials increasingly dominate the airframe, meaning their reliable, effective repair is critical for operators and the industry, alike. This technology will allow the efficient, cost-effective and high-quality preparation of almost any composite assembly for repair.
Rob, keeping planes in service longer is certainly one of the benefits hoped for from this new technology. The primary benefits, though, are getting them back into service faster, lower cost, more consistent repairs, and techniques that don't shorten a plane's service life by damaging composites during repair (the lack of force or vibration applied to the structure).
Wow! Thanks for this, Ann. It's often the obvious solutions that are the most frustrating. The use of dirty, violent abrasive cutting techniques on composites is such an obvious no-no when it comes to disturbing the fiber alignment and potential of layer separation in non-damaged portions of the material. I'm guessing previous attempts to cut fiber/resin composites with a high-power laser resulted in either a puddle of goo or a fire. Kudos to Lasertechnik for developing an appropriate combination of laser power, frequency, modulation, and beam profile for use with composites. This will have wide applications.
William, I assume that this technology relies on very precise control of the laser to work. There must be some new advances in laser focus or control to make it possible. It is, becuase of the results you mention, not an obvious choice, but someone has figured out how to make it work (werk?).
Composite repairs cannot be fully checked for quality via visual inspection like conventional repairs. I often wondered how they plan to handle this problem. And well, of course, let a robot do it - they are consistant and have no bad days.
I find it amazing what SLCR Lasertechnik can do with regard to coating removal. They claim, for example, that they can strip the paint from a part while leaving the primer intact. They can also remove paint from selected areas without the need for masking. I can think of a lot of occasions in which the ability to do these things would have been very useful.
By the way, it appears that the company is called SLCR (Selective Laser Coating Removal), not SCLR. The name was misspelled in GKN's press release.
Hey William, glad you liked this story. It does seem kind of 20/20 in hindsight, especially the "don't bang on that complex composite layer" part. The other part that also seems obvious is the crossover from removing coatings on composites via laser--which SCLR Lasertechnik already does, and which sounds like a delicate process--to using lasers to repair composites with what sounds like a very similar method. Maybe someone from SCLR Lasertechnik was having a beer with someone from GKN Aerospace, and one of them said "I wonder what would happen if you used this for that...?" Just a guess.
Chuck, Boeing doesn't seem to like to discuss this subject in any detail, so their specific plans are unknown. Since GKN Aerospace is a major supplier to Boeing, one can always make reasonable guesses. That said, Boeing was having a lot of trouble earlier this year with apparent delam issues of the 787's composite fuselage: http://www.latimes.com/business/la-fi-0223-dreamliner-problem-20120223,0,6402954.story
Boing has com out with many very innovative systems over thee years and unfortunately only they for the most part can use or own them mainly due to excessive implementation costs. For the rest of us in the aviation industry reality is that this will boil down to the newest ie cheapest labour a angle grinder and not much more. The repairs will be safe but not as lightweight or perfect. Even today simple repairs such as this involving rights and alum patches are commonly sent to third world countries where thee labour rates are much cheaper. You can pay a mechanic $50 an hour or send to costra rica or Belize and spend a small fraction. Its done all the time and perfectly legal.
Interesting, KingDWS. I didn't realize aviation repairs were getting outsourced to low-cost labor markets. Do these low-cost sites have to produce skilled technicians. Are there regulations governing the quality of these repairs?
In theory the shops and people or someone has to have the same certifications as up here. You only need one person with the right tickets to sign things off and that's legal. This has been going on more and mores since about the 80"s and perhaps longer that's when I started. Put it to you this way, have you ever flown south on what seemed like a old rattly hunk of junk and then a week later fly north on a nice fresh one. Most of these shops do the very expensive major checks and inspections, the fuel cost is actually not much of a factor to get them down there even when flown empty. Like I said the robots are cool but cheap labor rules.
The normal work being done are the major checks which are very labor intensive or repairs such as corrosion that require a lot of labor as well. These type of operation usually require the airplane to be almost stripped bare during the repair. The day checks are normally done at the airlines maintenance facility or regional facility these are fairly minor compared to other inspections or repairs. These shops and repairs still need to be done according to the book so they are licensed and the materials are the proper ones. The ones I would worry about are from peru columbia a few other places those are not exactly reputable repairs (I'd rather walk :-) )
Unfortunately the whole industry is very cost driven so this is going to become more common.
KingDWS, since Boeing et al are the big commercial plane makers, it seems that your comments about repair don't refer to them. So what class of planes are you talking about? They don't sound like aircraft most of us are likely to fly on. Is that correct?
Unfortunately for your flying piece of mind I am referring to Boeing and practices. You have to keep in mind that the airframes keep getting passed down to smaller and smaller operators with smaller operation and maintenance setups. Eventually they just no longer become viable and get junked if they have no cargo capabilities or face noise or excessive fuel burdens. There are still 727's flying cargo and those had to be one of the worst for noise and fuel burn but they are fast and there are cargo door kits still available. The thing you have to keep in mind is if you see tape holding anything together fake a heart attack and get off :-)
KingDWS, I haven't flown a lot in the last few years but before that I didn't see anything as scary as what you describe. OTOH, I have wondered about the apparent decline in maintenance quality in the last decade or so, which became evident after several high-profile near-misses in the air and on the tarmac.
That's pretty normal in the industry. And it; s being done by certified by low cost shops. You definitely won't see robotics anytime soon in say Belize. That's a different thing, that's air traffic and ground control. That is all due to human error or just over crowding unless the brakes went and it rolled out in front. As bad as these sound when was the last major crash? And compare that to driving, then you start to see how safe it is. The problem is no one reports a fender bender even in a bus. Take those same people put them in an airplane bump into a building or ground vehicle and its coast to coast news. It just doesn't happen that much so when anything does it gets way over blown as to its importance. So now we know airplanes , cars, bikes, trains an ad walking are no good guess we are stuck annoying everyone else over the internet :-)
I think the other differences in car vs airplane accidents are key: cars have (usually) 1-2 people, not tens of people; cars are on the ground, not in the sky, so damage is likely to be greater in a plane crash; cars are driven by private citizens, not company employees; car passengers are more like to travel for "free" vs the ticket price for the privilege of flying in a commercial aircraft with no legroom, absurdly low baggage allowances and crummy food. All of those factors raise our expectations, and I think rightfully so, for the safety of air travel over car travel.
The art and science of composite repair is constantly evolving. The advent of the B-787 class of aircraft is a game changer. In the past, composite parts have been considered "secondary structures", such as flight control surfaces, landing gear doors, floor panels, etc. Repair procedures were fairly well understood and integrated into the maintenance programs as normal operations. Now, with the composites forming a major portion of the load-bearing structure, the industry has to really step up their game. Our company is one of a few supplying composite repair systems for this purpose. We see every day the struggles the OEMs and the repair activities are having with these issues.
There are really four phases or issues of consideration when repairing composites. 1. Identification of the damage. 2. Preparing the area for repair (removing damaged material). 3. The actual repair (replacement of damaged material) 4. Verification of the process (QA /QC, NDT).
The subject of this article partially addresses #2. A few of the posters flagged some of the issues involved. How practical is the robot for use in-situ scenarios? How well can it negotiate compound curves, fasteners, varying material densities, and unknown sub-strucrures? One poster alluded to "dirty, violent abrasive cutting techniques on composites". Removal of damaged material is actually more surgical, with the use of hand-held routers, die grinders, and the like with diamond and carbide bits designed for this purpose. There is a large human expertise factor required for all phases of composite repair. The application of robotic technology to as many of these processes as possible is laudable, but more development is required. There is as much art as science involved with complex repairs.
Since most composite repairs require the application of heat to cure the aerospace materials, the real challenge is ensuring that heat is uniformly applied and reaches all parts of the material under consideration. This is especially challenging when dealing with carbon-fiber structures. Carbon conducts heat relatively well. The heat wants go everywhere, not just where it is needed. We are actively working with the OEMs to develop equipment and technology to ensure this is possible.
All phases of composite repair have come under much closer scrutiny from the FAA recently. They see the potential for a catastrophic event due to an improperly performed repair. It's back to basics: Training, proper procedures, process control, verification. Welcome to the friendly (safe) skies!
J.Lombard, thanks for such a clear summary of this complex issue (and sub-issues). I'd sure like to find out more about your company for use in possible future articles. Can you contact me by email? I can be reached at firstname.lastname@example.org.
I agree with JL. While this is a cool gadget you'd still need a human for judgement and only part of the process.
If I get it right it evaporates the resins leaving the fibers. That would take 1k deg F likely not to damage CF or glass. If Kevlar types it would destroy them as the resin.
I'd not just slap a patch on that as resin must reinfuse completely to good resin. Possibly a weak area of not quite vaporized resin would block the new resin from mating.
There are many technics to access damage and repair it without such high priced robots.
Ann, Speaking of recycing plastics just where online is the article on turning plastics into diesel, gasoline? It's the article I've learned more I need than most of the rest here combined. I got it in print, here is it online?
Jerry, thanks for asking about my upcoming May feature article on turning recycled plastics into fuel. The feature articles you see in the print edition usually appear online a few days later. Watch for it!
It is amazing to see new technologies developed in my lifetime come to to forefront of engineering in action. This new material did not exist at the beginning of my career, and now they are using it in huge airplanes in place of aluminum. Wow, that was fast! And now they have automated repairing the stuff! It's great to be an engineer!
Wow, engineering methods never cease to amaze me. The application of robotics to repair composite materials for aircraft is an awesome idea. With latest innovations in machine vision technology, robots can assist in spotting defects in aircraft structures particularly composite materials. This concept of using robots to repair aircrafts reminds of the scene in Star Wars The Phantom Menance where the R2 units were deployed to repair a damage space fighter while engaged in battle with the Imperial Fighters. Truly Amazing!
Oak Ridge National Laboratory has developed a surface preparation method to improve joining carbon composites with aluminum, with potentially far-reaching ramifications for high-volume industrial applications.
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