The engineering team quickly realised that this process was not achievable with conventional manufacturing methods and consulted advanced prototyping service provider, Wehl & Partner, for advice. The Navarra-based company offers a wide range of solutions from conventional machining to additive manufacturing technologies. With Wehl & Partner’s help, IDEC found an alternative solution in FDM® additive manufacturing, which enabled them to test the suitability of the RTM process in conjunction with the aircraft wing project. ULTEM™ 1010 resin was chosen to produce the preform tool. The material’s excellent chemical and high heatresistance enables it to withstand temperatures exceeding 150 °C.
“We couldn’t have done this with a conventional epoxy resin, which would have become unstable or even break beyond temperatures exceeding 140° C,” explained Diego Calderón, Structural Analysis Manager at IDEC. “Although there are epoxy resins resistant to such high temperatures, these are very expensive, and they would not have been financially viable for our project.” The ability of ULTEM™ 1010 resin to withstand the required temperatures and pressures simplified the preform production process. According to Calderón, the preform is so solid that the team can use it for at least 25 cycles, something simply not possible with epoxy or other additive manufacturing technologies and similar materials. The material was also an excellent option to replace metals, thanks to its superior tensile strength and non-conductive properties, vital for the electrical heating application. The result offered a smooth surface finish, enabling optimal adherence with the carbon fibre material and a perfect moulding.
Using a Stratasys F900 acquired through local partner, Pixel Sistemas, Wehl & Partner was able to manufacture a large-scale preform tool using the system’s large build tray. The tool was produced in just 60 hours – significantly less time than if the team had selected a more traditional method of manufacture. “With CNC machining, it would have taken us at least four weeks to produce this type of part,” affirms Javier García, Director of Wehl & Partner. “Not only did the use of additive manufacturing slash the production lead-time on the preform tool, but we also expedited the whole composite moulding process.” “With the use of ULTEM™ 1010 resin, we’ve obtained a preform tool with perfect mechanical properties and have been able to deploy this innovative step in the RTM process.
This has seen us reduce the composite heating stage from one hour to only ten minutes by flowing the electrical current directly through composite fabrics,” he continued. “This would not have been possible without FDM additive manufacturing.” The team has also been able to save up to 67% of the costs of CNC machining aluminum, a technical innovation which met the initial objective to reduce manufacturing costs. The solution provided by Wehl & Partner has contributed to IDEC’s competitive RTM innovation. It also demonstrates the many possibilities FDM additive manufacturing offers composite moulding applications, while adhering to the rigorous technical requirements of the aerospace industry.
