The environmental challenge (reduction of fuel consumption) for aircraft industry is driving new handicaps in this sector as improvements on fuselage and aircraft engines and light weighting. Indirectly, reduction of maintenance operations has also influence on environmental footprint by reducing the waste parts, oils or greases, etc. The use of lightweight materials as titanium alloys has been growing up in the aircraft industry alloys for weight reduction. However the high ratio between the raw material used to produce a component and the mass of the component (“buy-to-fly”, BTF ratio ) raises the scrap material, the environmental impact and the production costs. Additive Manufacturing (AM), and particularly Wire Directed Energy Deposition by Laser (W-DED-LB) is being the alternative manufacturing process to reduce waste material and the production costs. W-DED process is becoming a key manufacturing process in aerospace development, mainly due to high deposition rate, the ability to build larger structures and high efficiency in material compared with powder AM technologies. W-DED-LB techniques have an important drawback linked to a complex heat management. The implementation of inappropriate building strategies would result in important distortions and residual stresses in the final built component. The implementation of a novel manufacturing methodology able to ensure the quality of the built component is a key issue to overcome. The combination of the manufacturing strategies and the main advantages of coaxial W-DED-LB process proposed in ADDIFLAP will enable to manufacture a low distortion near net shape (NNS) for flap track structure.
On the other hand, one of the breakthroughs in tribology is to design solid films with desirable friction and wear properties across the load, speed and temperature ranges to reduce the use of lubricants minimizing the maintenance of the components. Addition improvement for carriage system based on a sliding pad concept proposed in ADDIFLAP will support the replacement of the actual roller system, reducing the maintenance and the use of greases during the service life of the aircraft.
From the work performed along the ADDIFLAP project, main objectives of ADDIFLAP project have been succuesfully reached. A full-scale flap track support has been manufactured by W-DED-LB process according to the manufacturing strategy developed in the project, reducing the distortion of the base plate below ±1mm. The demonstrator was finally machined to target geometry with a reduction over 50% in the BTF ratio compared to conventional machining from a Ti billet.
From the model tests PEEKCA30 was selected as the final material to manufacture the sliding system solution. To reach this good wear performance of PEEKCA30 on the titanium surface, a hardmetal coating was applied to the titanium surface. So, the flap track surfaces in contact with the sliding pad has been coated to fulfil the wear/friction requirements.
Finally, the test rig required to perform the final wear tests of the sliding pads over the flap track support has been designed and manufactured. Assembly of whole components was performed and wear test on full component to assess the wear performance of the sliding pad system is ongoing.
According to ADDIFLAP results further development is required before being ready for production environments. Further R&D will be required to optimize mechanical properties of deposited material, the new strategy for cost-efficiency, production cycle time, and certifications for the material must be obtained. The final design of the sliding-pad should be optimized after manufacturing several prototypes and testing them to ensure robustness and cost-effectiveness.
