Abstract

The content of this project is focused on the development of a process to reuse uncured A350 prepreg scrap obtained in production plants. The main aim is to reduce the current buy to fly ratio, which is the used raw material versus the material that will finally fly and, thus, to achieve clear benefits in terms of environmental aspects. The key properties of the new virgin material obtained after this reusing process have been evaluated in order to assess potential applications in aeronautical or other fields (e.g. automotive, sport, civil works…). Additionally, some aeronautical demonstrators or pilot cases with the reused material and process were produced. Regarding the key conclusions of this workt up to now: an effective process has been developed to reuse A350 uncured prepreg scrap, mainly mono-ply, based on chopping the prepreg to obtain a new virgin material, which will be used to produce a part by applying a compression molding process. Although the properties of the new raw material show high scatter, some of them stay close or even higher versus the reference (e.g. CAI). To end with, several aeronautical demonstrators with acceptable quality have been produced with the prepreg reuse process developed in this project (e.g. complex brackets, gaskets, manholes…).

Abstract

The tasks and conclusions presented in this article have been developed in the C2CC - "Cradle to Cradle Composites" project implemented in the framework of the EIT-Raw Materials program. This project proposes the replacement of metallic components in automobiles by using composites made from raw materials with lower environmental impact: (i) basalt fibers of mineral origin, (ii) furanic resin systems of natural origin and (iii) bio-based epoxy resin systems recyclable through the use of cleavable hardeners. In this article, the raw material characterisation tasks and the prepreg manufacturing process are discussed, using two manufacturing processes and their corresponding equipment. The tasks of obtaining thermoplastic matrices from the cleavable epoxy systems will also be documented, showing the demonstration prototypes developed in the project, both from the thermoset composites and from the recovered thermoplastic composites resulting from the recycling process.

Abstract

Industrial automated tape layup methods significantly increase the productivity, precision, and efficiency of manufacturing methods for large aerospace parts; however, although they allow reducing scrap fraction compared with manual processes, it keeps being too high, requiring waste management. The scope of the MC4 project, part of Horizon Europe program, is to not only recycle that scrap material, but also to transform it to a completely new, functional part, without the need of adding additional material other than this recycled scrap. This can be achieved by cutting that material into strip shape and reducing it to a specific thickness by means of a compacting process. Those homogenous thickness strips can then be processed using a heated plate press to form it to any needed shape. Mechanical properties will be studied and compared to the original material, to check if this process is suitable for the manufacturing of functional parts. As this method does not separate the original resin and fiber, it avoids the usage of chemicals that can damage the properties of the material and increase the risk and pollution of the process, which is ideal for a recycling process.

Abstract

It is estimated that the aeronautic industry in the European Union produces annually around 10 tn of uncured prepreg scraps, generated mainly from manual and automated lamination processes of composites, and that the treatment cost for these residues is between 3 and 12 € per kilogram.

This work presents a technology for the reuse of the unidirectional prepreg scrap using a machine that allows the manufacturing companies, mainly form aeronautic sector, the reuse and valorisation of the leftovers of PREPREG in the workshop, involving a reduction in the economic and environmental impact.

The developed solution consists in a machine able to perform the needed processes to reuse the prepreg scrap leftovers in an automatic and efficient way, maintaining the quality and the material properties for the manufacturing of non-critical components. The equipment integrates different technologies that include computer vision to identify the shape of the leftovers and the fibre direction, cutting technology to generate regular rectangular chips aligned with the fibre direction, and a robotic system to pick and place the chips generating an ordered pattern.

The result of the process is a material sheet aiming to control the mechanical properties by using homogeneous chips with controlled fibre orientation following a predefined pattern.

Abstract

The use of CIDETEC's patented 3R technology allows the development of thermoset composites that are intrinsically Reprocessable, Recyclable and Repairable (3R). These materials are very interesting for sectors as diverse as energy, transport, and construction, as they maintain the high performance of conventional thermoset composites and can be processed using common manufacturing technologies. The use of prepregs is one of the methods used to manufacture thermoset composites, but it is a labour-intensive and cost-intensive process. In addition, the epoxy matrix of prepregs, which is partially cured (called B-phase) and sticky, requires them to be stored cold (refrigerated or frozen) and, once the due date has passed, they cannot be used to form a consolidated laminate because of their lack of adhesion. The dynamic character of the 3R epoxy resin described here makes it possible to manufacture what we have called "enduring prepregs", which are (semi-)cured, non-perishable prepregs, with the advantage that they can be stored at room temperature without losing their adhesion capacity. Moreover, it is possible to process them using techniques as diverse as AFP (automated fibre placing) or thermoforming to manufacture multilayer composite parts. This communication will present the latest advances and the objectives of several European projects funded under the H2020 (CARBO4POWER - GA.953192) and Horizon Europe (BIO-UPTAKE -GA. 101057049 and GENEX -GA. 101056822) frameworks, which are working on the development and optimisation of these "enduring prepregs" for different sectors.

Abstract

The new Airbus A350XWB has the largest % of an aircraft primary structure elements made of composites ever. Thus, it has been a huge challenge to manage thousands of CFRP Tons per year in the part manufacturing plants, and consequently, several initiatives to reduce, reuse and recycle scrap material has been developed during last few years. Illescas Plant is introducing new processes to reuse and recycle CFRP material from wing covers and fuselage parts. Two initiatives are running these days: Reusing of CFRP (prepreg) end of spools and end of rolls to manufacture rowing for stringers that allows to decrease the purchased material in the Plant.

Abstract

Within the European platform Europe's Rail, whose objective is to promote research and development activities in the railway sector, can be found the PIVOT-2 project (Grant Agreement no. 881807), which addresses the implementation on track of light and environmentally friendly vehicles, reducing energy consumption and therefore the CO2 emissions derived from the transport sector.

To meet these objectives, the project seeks to achieve the weight reduction of primary structures. This way, the use of composites materials appears as an interesting alternative in a sector where their use has been very limited to non-structural components, largely due to the need to comply with fire protection regulations (EN 45545) [1]. Thanks to the development of new resins, the possibilities of these materials are increasing, being necessary to evaluate their performance in new applications.

Similarly, the characteristics of the railway industry mean that the manufacturing processes of composite materials widely used in other sectors, such as the aerospace, must be adapted. Likewise, and due to the requirements of the final product, it will be necessary to adapt the materials to these new applications, developing materials with higher grammage or ply thickness than those currently used.

The project evaluates the automatic laying of different materials developed for the railway sector. The behaviour of flat laminates is analysed, as well as the lamination of the material on core structures. Finally, studies are validated with the manufacturing of a train carbody section, using automatic lamination processes (ATL).