The open-moulding process is a manufacturing method used for the creation of concave fibre-reinforced polymer parts, such as bathtubs and boat hulls. The process involves manually placing fibre over a mould, then pouring or spraying on a liquid thermosetting plastic. The process is used where parts are too large or complex for other moulding technologies, or where parts are required in low numbers. The open-moulding process has numerous drawbacks. It is very labour intensive and slow, also meaning expensive. Open mould factories are thus often located in low-wage countries. For Europeans, this creates long lead times and supply chain vulnerabilities. Open moulding also faces technical limitations concerning the complexity of the mould shape. Furthermore, the process works exclusively with thermosetting materials, which cannot be remelted or recycled. These materials emit toxic fumes, putting workers at risk. So open moulding has a poor environmental footprint.
Continuous fibre additive manufacturing
An alternative method is long overdue. The EU-funded CFAM project developed a replacement. The project brought an early-model machine to technology readiness level 9 (ready for market) and introduced potential customers to it. The new process essentially consists of a special 3D printer that deposits a continuous strand of the moulding fibre (either glass or carbon). Instead of thermoset materials, which can only be used once, the new process adds thermoplastics that can be remoulded. This combination is unique and patented.
Rapid production and verification
The new machine can produce parts up to 4 x 2 x 1.5 m, and at high speed. “This both automates and accelerates the process of making fibre-reinforced large complex parts,” explains project coordinator Lucas Janssen, “or the moulds used to make these parts.” The machine can produce an average output of 15 kg per hour and a maximum of 25 kg/h, over 100 times faster than conventional 3D printers. “The heart of our machine is the extruder, or printing head,” adds Janssen. “It’s fed with thermoplastic pellet material, which is melted under high temperature and pressure.” The extruder has been designed to accommodate virtually any thermoplastic. The new process adds the continuous fibre at the end of the extruder. The extruder is moved around in 3D space, either by a robotic arm or gantry system. The CFAM team tested, verified and optimised the process. The system has been demonstrated via 35+ pilot projects and with more than 20 hardware solutions. Although industry response was slower than expected, the system is now well placed to be successful. Users will be companies producing moulded products for maritime, construction or infrastructure, and aerospace applications. The machine can cost-effectively produce complex parts in low numbers, and in many cases it will allow in-house production. By using this development, the process of making the products will be easier and largely automated. This eliminates the need for skilled craftsmen. The CFAM team will continue developing the technology and expanding the market. This will involve further demonstrations, focusing on specific problems and challenges within the industry.
CFAM, manufacturing, thermoplastic, open moulding, continuous fibre, 3D printer, industry