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aircraft structures not currently being laser peened. The US Navy’s Fleet Readiness


Center East (FRCE) has also recently completed verification of a laser shock peening process, which has successfully been used on an F-35B Lightning II aircraft that has since returned to active service. The process was used by FRCE to strengthen the frame of the F-35 without adding any additional material or weight, which would otherwise limit its fuel or weapons-carrying capacity. This helps extend the life expectancy of the fifth- generation fighter, which is a short takeoff-vertical landing variant flown by the US Marine Corps.


Laser drilling Modern aero-engines contain approximately 500,000 holes – around a hundred times more than engines built in the 1980s. Aircraft manufacturers are also producing increasing quantities of a range of other components with a high number of drilled holes for riveted and screwed joints. Therefore, for aviation in particular, laser drilling has enormous market potential, offering a precise, repeatable, fast and cost-efficient process. For instance, new high-power


femtosecond laser systems are being developed for highly productive yet precise micro- drilling of holes into large titanium HLFC (hybrid laminar flow control) panels destined for mounting on wings or tail stabilisers. These panels lower


fuel consumption thanks to sucking air through the small holes and thereby reducing frictional drag. Due to laser drilling being


contact-free, the processed material does not need to be secured in the same way as if it were machined with conventional tools. Another advantage of being contact-free is that no tool-wear is experienced, which represents a particular advantage when drilling CFRP components, which, due to their hardness, produce an exceptionally large amount of wear on traditional tooling. Laser drilling can also be carried out at very high speeds, so excess


“Laser structuring can increase an aircraft’s repellence of water, ice and insects, which can stick to its surface and increase drag”


damage from heat is not inflicted on the material being processed.


A bimetallic combustion chamber with GRCop-42 L-PBF liner and Nasa HR-1 LP-DED jacket made by Nasa


Additive manufacturing Laser additive manufacturing (AM), in which lasers melt successive layers of powder to build up the shape, is also gaining rapid traction in the aerospace industry. A leading California- based rocket company even recently ordered two 12-laser 3D printers to make its space missions more affordable and efficient by creating lighter, faster, and more robust space components. While a lot of projects are still in the test stage, laser AM has already been successfully used on two Mars missions. Nasa’s Curiosity rover, which landed in August 2012, was the first mission to carry a 3D-printed part to Mars. This was a ceramic component inside its Sample Analysis at Mars (SAM) instrument, and was part of an ongoing testing programme to investigate the reliability of AM technologies. Meanwhile, Nasa’s Perseverance


12 LASER SYSTEMS EUROPE THE 2023 GUIDE TO LASER SYSTEMS


Laser peening can mitigate stress on components such as jet engine fan blades


rover, which touched down on the red planet in February 2021, contains 11 metal parts made with laser AM. Five of these parts are in Perseverance’s Planetary Instrument for X-ray Lithochemistry (PIXL) instrument, which is searching for signs of fossilised microbial life on Mars. These components needed to be so lightweight that conventional techniques such as forging, moulding, and cutting could not have produced them. Nasa has also been


experimenting with using laser AM to manufacture rocket components. In one study, a rocket engine combustion chamber was fabricated from a copper alloy. Continued development of this laser AM has resulted in that component being created for roughly half the cost and in a sixth of the time required by traditional machining, joining and assembling. Since the copper alloy used is highly reflective of IR lasers, Nasa is now looking at how green or blue lasers could improve efficiency and productivity. Although the use of additive


manufacturing in aerospace is currently at an early stage, growth is expected over the next 20 years.


Laser texturing Laser texturing is also a very new application being explored in the aerospace industry. Here, ultrafast lasers are used to produce micro- and nanostructures on the surfaces of aircraft via a technique known as direct laser interference pattern (DLIP), which is used to


produce a natural ‘lotus effect’ that helps prevent surface contamination. Innovative optics split one


powerful ultrafast laser pulse into several partial beams, which are later combined on the surface being processed. The microstructures that are generated, when viewed under a microscope, resemble microscopic halls of pillars or corrugated iron roofs. The distances between the pillars can be between approximately 150nm and 30µm. Such structures mean that water droplets no longer wet the surface and stick to it as they do not have enough grip on the surface. The advantages of this for aircraft include increased repellence of water, ice and insects, which can all stick to the surface of an aircraft, increasing its wind resistance and thus fuel consumption. Applying such laser textures will reduce the need for toxic chemical treatments currently applied to the surface of aircraft to avoid icing, which are known to age over time and damage easily. In addition, laser structures produced by the DLIP method can last years and do not raise environmental concerns. l


For more on the application of laser systems in the aerospace industry, visit:


www.lasersystemseurope.com/ industries/aerospace


@LASERSYSTEMSMAG | WWW.LASERSYSTEMSEUROPE.COM


NASA


Shutterstock/aappp


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