The advantage of laser cutting is the ability to process aluminum foil into different shapes quickly and accurately. This technology advantage has led to the commercialization of laser cutting equipment and has attracted many airlines. In the 1970s, major manufacturers evaluated laser cutting technology and found that microcracks from laser processing did not allow damage to the fatigue characteristics of the part. The potential weight gain has jeopardized the interests of the manufacturing industry, and laser cutting technology has been shelved by major airframe manufacturers.
Rotator parts and transmissions are manufactured using large metal billets forged. The fuselage also contains some parts made of forged materials, but most of the fuselage parts are made of aluminum. Traditionally, 7000 series zinc-based aluminum alloys have been used for processing because of the good static strength and fatigue strength of the alloy. Although the 7000 Series aluminum materials are well suited for aerospace applications, they are not resistant to high temperatures. Rapid heating, such as welding and laser cutting, can cause micro-cracks. Microcracks result in a decrease in fatigue strength. Welding and laser cutting are two processes that produce thermally induced microcracks.
Quality and process control are critical. Any process that brings uncertainty to the process must be controlled or eliminated directly. In the past, laser cutting presented significant challenges to quality control and consistency between different production batches.
In current laser cutting systems, the limitations of these laser cuttings in aerospace applications have been improved, including limitations in fatigue performance and reduced manufacturing process consistency. Now, the laser system greatly reduces the size of the heat affected zone (HAZ) and the corresponding microcracks. During the laser cutting process, the technicians have been able to control the cutting parameters and use the calculator software for precise repetition. These technological advances have led to rethinking whether laser cutting is suitable for the production of fuselage structures. The fuselage structure is mainly made of 7000 series aluminum materials.
Fatigue fractures typically occur where stress is concentrated, such as the edge of a part, where the geometry changes, or where it is joined. There are many different ways of joining the fuselage parts made of sheet metal, and most of the fatigue cracks occur at the joint. If the laser is not used to cut the small holes in the joint, the laser is mainly used for edge cutting of the part. For other effects, the most vulnerable connection locations can be used to illustrate the microfractures caused by laser cutting compared to the joints. In this way, we can conclude that if a part is likely to break at the joint, the laser cutting technique will not further damage the fatigue characteristics of the part.
The laser cutting process allows for faster machining of consistent parts, which is more efficient than conventional machining. Laser technology is expected to reduce processing time and production costs. For a long time, in the processing of 7000 series aluminum plates, the advantages of lasers have not been realized due to the reduction of fatigue performance.
Recently, innovations in laser systems have led to a renewed assessment of the advantages of laser-cutting aluminum for aviation. Initial tests have shown the potential of laser technology in airframe processing. Future fuselage systems and existing designs should not exclude possible applications of lasers in this airframe system due to past experience. We should maintain an open attitude to analyze the various situations to determine whether laser technology can bring product benefits.
