In the aviation industry high-performance thermoplastics are challenging metals in many fields. In this paper a pipe-extrusion process for high-temperature polyetherimide (PEI) and polyetheretherketone (PEEK) is presented. Both the weight advantage over stainless steel pipes and the price advantage over titanium confirm the huge potential of thermoplastic pipe systems in the aviation sector. In these studies extensive material tests were conducted on different types of PEI to fulfil the high standards of aircraft. The media resistance and especially the reactions with hydraulic fluids turn out to be the most challenging requirements. Various parameter studies were carried out and led to considerable improvements in processing at high temperatures in the extrusion process. It transpired that small changes in the process parameters and environmental influences are the greatest obstacles to error-free production. Adjustments to the thermal management of the calibration system significantly improved the robustness of the process to the extent that PEI-pipes of different wall thickness were ultimately produced in reproducible quality. Therefore the nozzle-area was analysed using thermal imaging to generate input parameters for complex analytical calculations of the temperature-zones during calibration.
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