ECOCLIP main objective has been the development of new recycled material from LMPAEK material reinforced with continuous carbon fiber. For this purpose, different formats of scrap material have been taken, crushed and screened. Subsequently, the shredded material was separated into 3 fractions, the smallest ones for 3D printing, the next ones for injection moulding and the last ones for reprocessing. During the project, the reprocessing study was carried out, crushing the larger particles, and dividing them again achieving a cycle efficiency of 97%. Once the recycling cycle was studied at a laboratory scale, the rout was taken to industrial level, using UNTHA cutting mills for processing and avoiding screening. Subsequently, this shredded material was blended to have different fractions of carbon fiber. They were studied rheologically, mechanical and thermal properties. This information was introduced in an injection simulation program to know which of the materials would be optimal for ECOCLIP parts. As a result, the 40%CF blend was selected as optimum, since some of the larger and more complex geometries could not be filled with higher amounts of fiber.
In parallel to this material selection, modifications were made to the parts to ensure injection and printing. The necessary moulds were created and used to produce frame clips (400) and system brackets (46) once all the injection parameters were defined. To validate 3D printing as a new technology to manufacture aeronautic parts, the same material was used in direct printing of pellets, achieving high fiber percentages in the final part and a better dimensional accuracy than injection. Both processes, were validated through standard specimens both mechanically and thermally.
Transversally to these, texturing was developed for the EDs. This texturizing favours the bonding between the clips and the MFFD by means of ultrasonic welding. Different geometries were studied and textured on metal inserts that were then introduced into the injection mould to replicate them. Sigle lap shear tests were performed, proving that the ridgets geometry was optimal. Once the texture was selected, inserts were made for the final clip mould resulting in a part ready for installation in a single injection step. To test the bonding, corner bending test was modified for which LMPAEK continuous fiber laminates were welded to the clip. This was used to check that the required strength was achieved.
During the project, both economic and environmental information was collected, which made it possible to realize the economic and environmental cycle of recycling. In this way two scenarios cradle-to-door and cradle-to-grave were analysed. The cradle-to-grave results indicate an improvement in economic and environmental performance thanks to the reduction of fuel consumption by lightening the weight of the parts. Therefore, it was possible to develop a new injectable material to manufacture aeronautical parts, which can also be welded leading to an improvement with respect to the current situation.
Regarding dissemination and communication, the results of the project have been presented on workshops, congresses , and exhibitions. These results include the work performed by recycling carbon fiber reinforced thermoplastics, injection moulding, 3D printing, and ultrasonic welding, among others.
