Future aircraft manufacturing: competition for materials and processes is growing

In the future, around the forming, processing and assembly of metal and composite parts, aircraft manufacturing will further develop in the direction of “big”, “fine” and “provincial”, which will bring new challenges. In response to these trends and challenges, this paper focuses on six hot topics in future aircraft manufacturing. These topics will be the focus of development in the aircraft manufacturing field in the future, and will also be a concentrated expression of the competitiveness of aviation manufacturing.

White and black contest

The competition between the Boeing 787 and the Airbus A350 for composite materials was once the focus of the industry. It also made people realize that carbon fiber composites have replaced aluminum alloys for the first time and become the material of choice for future dual-passenger aircraft. The black plastic of carbon fiber composite material seems to have swept its white predecessor, aluminum alloy, overnight.

Faced with an aggressive offensive of carbon fiber composites, aluminum alloy suppliers led by Alcoa also launched counterattacks to develop more advanced aluminum alloy materials for the weaknesses of composite materials. The third generation of aluminum-lithium alloy is an important chip in this "white and black contest". The newly developed 2099 aluminum-lithium alloy is much higher than the existing 7150 aluminum alloy in combating exfoliation corrosion. Compared with carbon fiber composite materials, aluminum-lithium alloy materials are not only aerodynamic, anti-corrosive, recyclable, but also 10% lighter, 30% lower in manufacturing, operation, and maintenance costs, and lower overall risk. Used on the Boeing 787, Airbus A350 and Bombardier C-Series aircraft.

At the same time, carbon fiber composite manufacturers are also studying ways to reduce costs and improve quality. Non-autoclave (OOA) forming has been the focus of innovation in the industry, including advanced room temperature curing resin systems, self-heating manufacturing tools, and compression molding, microwave curing and laser curing methods. At present, in the field of non-autoclave, many achievements have been made, such as the advanced all-composite conveyor (ACCA) manufactured by Loma, Boeing and Loma, respectively. ) Process manufacturing of large parts and the like. In addition, in order to solve the problem of delamination, slow speed and tool wear in composite cutting and drilling, Loma joint tool suppliers have developed chemical vapor deposition (CVD) diamond coated tools, which greatly improve the processing efficiency and quality; Ma and Boeing are also actively cracking the dimensional accuracy of the composite-aluminum/titanium sheet drilling, and have achieved positive results.

In the foreseeable future, competition for carbon fiber composites and advanced aluminum/aluminum-lithium alloys will intensify, which is good news for the aircraft industry, because this competition will make the aircraft body structure weight, cost, reliability, There is a large increase in maintenance and improvement space, and bring them more design choices.

Addition and subtraction

In 2012, the fiery heat of additive manufacturing caused people to think about whether to use "addition" or "subtraction" in the future. Compared with the traditional processing method of removing materials, additive manufacturing can greatly reduce tooling requirements, reduce material consumption, and shorten manufacturing time. It can also form novel parts and complex structures that cannot be realized by conventional methods, which may cause product design and manufacture. A major change.

It is also because of the revolutionary potential of additive manufacturing in product design and manufacturing, which can meet the overall lightweight requirements of future aircraft manufacturing for structural parts. Boeing has applied more than 200 additive-made parts to 10 aircraft platforms for military and civilian use, and has a set of technical maturity level (TRL) guidelines tailored for additive manufacturing projects; Loma P-175 composite In the development of the drone, the structure of the carbon nanotube and the matrix powder by the laser sintering forming body is the biggest highlight.

The temptation of additive manufacturing technology is undoubtedly great. However, it still has many challenges in aircraft manufacturing. Its promotion speed has been slow in the production of physical parts. The US Defense Analysis Institute (IDA) believes that technology and manufacturing maturity, lack of talent and commercial environment, and inadequate standards and regulations are the three main reasons. They believe that the development of additive manufacturing technology should be improved in the short term. Efforts in the four directions of speed improvement, quality control and material discovery, and the government and industry should also pay attention to the commercialization of this technology.

In terms of “subtraction”, related manufacturers around the F-35, which has the largest number of procurements in the defense sector, have been developing advanced technologies to meet their precise, efficient and low-cost requirements. For example, Creare Corporation of the United States has developed a low-temperature processing technology called Indirect Cooling System (ICS), which uses an inert liquid pressurized fluid to achieve non-indirect cooling of the tool. For the turning of titanium alloy (Ti-6Al-4V), Increase tool life by 160%. At present, although the additive manufacturing technology will be introduced in the F-35, it is limited to the manufacture of several non-bearing small pipes and hinge parts, and before the feasibility of mass production and the feasibility of large-scale manufacturing cannot be proved. As well as the reliability under the large force, the "subtraction" processing will also dominate the stage of future aircraft manufacturing.

Robot mobilization

"Robot Story" is no longer the name of a movie, but a lively scene in the future of aircraft manufacturing. Robots can be used in the forming, machining, welding, assembly and painting of aircraft parts, performing composite pre-forms weaving, prepreg tow placement, metal powder laser additive manufacturing, non-destructive testing, part cutting, cutting, Surface finishing, laser peening, friction stir welding, laser welding, drilling, riveting, auxiliary positioning, handling, painting and coating thickness measurement. Especially in the assembly and spraying of advanced aircraft such as F-35, A400M, A350, C series, robots have become almost standard, becoming synonymous with fast, high precision and low cost. In the fields of robot metal welding and composite material forming, manufacturers such as Boeing and EADS, and equipment suppliers including MAG and EI are also jointly developing suitable robot systems to further expand the application range of robots in large-scale parts manufacturing. .

At the same time, it should be noted that the popularity of robots in the future of aircraft manufacturing is also subject to four problems to be solved, namely, the innovation of traditional concepts and traditional processes, the complexity of system design and system integration, the limitation of work space and load capacity, and the special purpose. Tooling and peripheral equipment. I believe that after these problems are solved, we will usher in the robot era of aircraft manufacturing.

Good horse with a good saddle

As the saying goes, "Good horses are equipped with good saddles". The efficient forming and assembly of precision parts is inseparable from excellent manufacturing equipment and excellent manufacturing tools (tools). Entering the composite age, its unique thermal expansion and pressure deformation characteristics make this even more important. In the future, the competition of composite aircraft will depend on the manufacturer's design level, manufacturing process and production capacity, as well as the quality of the tooling technology.

In the field of composite forming, a variety of new tooling materials and technologies have been developed abroad for autoclave curing and non-autoclave (OOA) curing. In metal tooling, the work is to significantly reduce the weight of Invar, the development of new metal materials, such as Invar / composite material tooling tested on the F-22 front fuselage; in composite tooling, focus on improving composite materials Performance, introducing nano-enhancement technologies such as isotropic HexTOOL tooling for A350 fuselage panels; in self-heating tooling, focusing on self-heating techniques that reduce heating cycle and energy consumption, such as for RQ-7B wings High-efficiency electric heating tooling for skinning.

In the field of composite assembly, manufacturers using advanced flexible tooling and fixtures will become an important means of shortening the cycle and reducing costs. Airbus has adopted two innovative flexible concepts on the A350. One is a flexible clamp based on Parallel Motion Mechanism (PKM), which eliminates the limitation of the number of spindles/assembly tools; the other is an economically affordable reconfigurable tooling (ART) from standard steel components. The packages are assembled, quickly assembled by means of a metrology system, and can be adjusted and recombined.

Love fight will win

Aircraft assembly is not only a part of the manufacturing technology level of a company or a country, but also a key process to shorten the aircraft manufacturing cycle and reduce the cost of aircraft manufacturing. Future aircraft manufacturing, how to assemble, is the key to determining the outcome. Both Boeing and Airbus are working to build an unprecedented flexible assembly system with six main features, namely automated drilling and riveting, digital measurement and control, modular clamping and positioning, unmanned handling and transport, Serial assembly and integration, virtualization simulation and reality. Among them, the first four features have been fully reflected, and the latter two features are also constantly enriching its connotation and application cases, showing the future development direction of aircraft assembly.

Airbus designed a flexible pulse moving assembly line (PML) for the A350 fuselage siding, allowing up to seven types of siding to be drilled at the same time. Each siding is assigned a suitable drilling robot according to the amount of the task. It saves space and supports efficient and transparent assembly of siding. To monitor all objects and personnel on the assembly line to safely load and unload components and accurately position automated assembly machines, Boeing participated in the development of a factory 3D laser scanning imaging system and pilot deployment on the 747-8 assembly line. Once the system is used for revenue, it will likely disrupt the current aircraft assembly management process and significantly increase production efficiency.

Are you mature today?

For the manufacturing risks in aircraft manufacturing projects, there is no scientific and unified measurement and management method in the past. After summing up a lot of lessons, the US Department of Defense has developed a management tool of manufacturing maturity, trying to measure the manufacturing risks. Management standardization and achieved remarkable results. Manufacturing maturity focuses on the ability of manufacturing systems to achieve the project's ultimate goal, measuring and unifying in the dimensions of technology and industrial foundation, manufacturing management, manufacturing management, design, materials, process capability and control, facilities, personnel, cost, and investment. A language that describes manufacturing risks. Now, many US Department of Defense procurement projects, such as the P-8A patrol aircraft, MQ-9 drones, and KC-46 tankers, must set manufacturing maturity milestones to monitor and reduce manufacturing risks.

The competition for future aircraft manufacturing has surpassed the process technology itself, and has essentially become a competition for technology maturity and manufacturing maturity. The innovation of process technology and the improvement of industrial foundation are prerequisites. Design simulation capability, material supply capability, process control capability, equipment development capability, and talent technical capability are all core competitiveness, supply chain management, cost management, quality management, manufacturing process management. Facilities management, personnel management, planning and schedule management are necessary safeguards. This also requires China's aviation industry to change its mind and be fully prepared to meet the more systematic and more complex competition in the future of aircraft manufacturing. (Assistant Researcher, China Aviation Industry Development Research Center: Liu Yawei)