3D Printing Aircraft Landing Gear And Repairing Titanium Alloy Blades

Aircraft landing gear is a type of component that is subject to huge forces. In order to adapt to the environment with high forces, these parts are forged with high-strength steel. However, since the advent of titanium alloys, aircraft landing gear has gradually switched to titanium alloy forgings, because titanium alloys have both high strength and low density, and can reduce their mass by more than 25%, which is very important for aircraft. The titanium alloy used in aircraft landing gear is Ti-10V-2Fe-3Al, with a tensile strength of 1190MPa, which is almost 2.2 times that of 7075 aluminum alloy. Many parts of Boeing B777 aircraft landing gear are forged with it. The Ti-6Al-2Sn-2Zr-2Mo-2Cr alloy still used in landing gear has high strength and toughness, but the price is relatively high. In addition, Ti-6Al-4V alloy is mostly used to forge helicopter landing gear parts. It is the most widely used titanium alloy for aerospace and general equipment. It has a lower price, and its strength and performance are lower than the above-mentioned titanium alloys.

The working conditions of aircraft engine blades are extremely harsh. Not only are the temperatures high, but they also have to withstand high pressure and high-speed airflow. Working in a harsh environment of "three highs", aircraft engine blades are easily damaged, especially the blade tips, so the maintenance workload is large. According to a report on the website of Aviation Weekly on September 15, 2023, in order to reduce the maintenance workload and extend the working time of the blades, Optomec and Acme Robotics Systems of the United States took about two years to jointly develop an automated work unit for repairing aircraft engine titanium alloy compressor blades, which is a world first. The original intention of the design and manufacture of this maintenance system is mainly to repair the tips of titanium alloy compressor blades that have been worn during the use of the engine, and it can also repair the damage of nickel-based alloy blade tips and blade leading edges. The automated work unit consists of 3 stations, which can perform blade tip grinding, 3D printing laser cladding and post-processing, including 1 automatic pallet loading and unloading station, 1 pallet flipping station and 1 robotic material handling system, and can also be equipped with other functions, such as automatic coordinate measuring machines and cleaning stations.

OptoMec said that compared with traditional titanium alloy blade repair processes such as CNC machine tool processing and tungsten inert gas welding (TIG), the automated work unit has a series of advantages: the speed of completing blade finishing is about 3 to 4 times faster than CNC machine tool finishing or manual finishing; compared with manual processes, the quality of repair is more stable; the cost is reduced by more than 70%, and there is no need for manual welding and manual finishing, which greatly improves the quality of repair. OptoMec said that the use of efficient and repeatable robot finishing technology can greatly improve the work quality of engine maintenance centers and reduce maintenance costs. The automated robot system can repair 85,000 titanium alloy compressor blades per year and has been certified by civil aviation regulatory agencies in many countries. Long-term commercial applications have shown that the system is completely safe and reliable. According to a report by the British aero-mag website on September 17 this year, the British Aerospace Technology Institute (ATI) launched a research and development project called "Landing Gear Industry Breakthrough (Ⅰ-Break)" with an investment of 22.5 million pounds. Led by Airbus, the project involves 15 companies, research institutes and universities. It will be the first time in the world to 3D print aircraft landing gear parts.

The Ⅰ-Break project consists of four work packages: WAAM3D is responsible for the industrialization of arc 3D printing production speed, microstructure and mechanical property control for high-integrity structural applications, online non-destructive testing, and the production of prototype parts of corresponding size and complexity on the upgraded RoboWAAM system; Cranfield University is mainly responsible for researching new WAAM processes and solutions and verifying the deposition of key alloys; Strathclyde University is mainly responsible for innovative online flaw detection technology; PeakNDT is a high-performance conventional and phased array ultrasonic instrument manufacturer, and is also responsible for online non-destructive testing technology research.

The use of 3D printing technology for aircraft landing gear parts can shorten the time to market of aircraft, improve product quality, and reduce carbon dioxide emissions by 20%. The research and development work of this project is scheduled to be completed by 2026. The manufacturing process of aircraft landing gear parts around the world will gradually shift from forging to 3D printing.