Cosimo project Recycled glass fibers: Sustainable materials for car and aircraft components
In a research project, several companies have joined forces to develop a manufacturing process for components made from recycled glass fibers — the first product is a battery housing cover for e-cars.
At the German Aerospace Center (DLR), researchers investigate how components made of sustainable materials can be used in automotive and aircraft production. Sustainable in this respect means: based on recycled fibers from the textile industry or reusable plastics. The essential technologies for suitable manufacturing processes already exist. They were developed by the DLR, the University of Augsburg and a consortium of eleven companies in the “Cosimo” (Composites for Sustainable Mobility) project.
The project aimed to process new plastic materials in the tried-and-tested RTM process. Resin transfer moulding is used primarily in the automotive industry. It enables highly automated production in high volumes. Only recycled glass fiber nonwovens were used in the project. The prototype for production had previously been created at the DLR Center for Lightweight Production Technology in Augsburg (close to Munich), ZLP. So-called chicane components were manufactured for demonstration purposes: Battery housing covers for e-cars made of nonwoven glass fiber materials.
Practical manufacturing process
How does this work in practice? The textiles were deposited in a metallic mould and impregnated with a liquid thermoplastic. According to the researchers, this has the advantage “that the later component can be re-melted as needed to weld it to other components.” A tool resembling a large waffle iron was used for the impregnation.
To give the component the desired shape and strength, the impregnated materials were pressed under high pressure in the hot press. After around six minutes, the 1.10-meter-long and 53-centimeter-wide part was ready.
The experimental battery housing covers for e-cars are made of polyamide 6, also known as “nylon”. Its use as an epoxy resin substitute is unique to date, according to DLR. Epoxy resins are common lightweight materials, but unlike polyamide 6, they cannot be recycled. Polyamide 6 also has the necessary thermoplastic properties for further processing.
Insights into the material during production
To be able to analyse the material properties during production, the researchers equipped the RTM production with sensors. “The biggest challenge was to determine the process parameters for complete impregnation of the nonwovens. Compared to conventional textiles, it was not at all easy to avoid dry spots. We managed to do this thanks to the sensor network, which allowed us to see inside the manufacturing process, so to speak,” describes DLR project manager Jan Faber.
The data obtained is intended to form the basis for future intelligent process controls. But it also has another significance: The team has developed a simulation model that can be used to virtually test individual production processes at any time. A data management system also synchronously records the measurement data of all systems; simulation and real operation can thus be directly compared. For the scientists, this means they can better understand material behavior and plant technology.
According to DLR, the project “has demonstrated the potential of the Cosimo concepts for industrial application in terms of sustainability, cost, and quality aspects and has been confirmed by the industrial partners.” Next, the researchers want to optimize the processes. Conventional battery housings for electric vehicles weigh around 300 kilograms. Components made of fiber-reinforced plastics could make them up to 40 percent lighter than aluminum or steel.