Improved Interface Strength for Overprinting with CF-LMPAEK

Kurzfassung

Continuous fibre-reinforced PAEK laminates are attractive for aerospace structures, yet the integration of out-of-plane features requires costly secondary joining. In this study, the feasibility of in-situ overprinting of thermoplastic TC1225 prepreg laminates with short-fibre-reinforced LM-PAEK (Victrex 231GRA) using a robotic fused granulate fabrication (FGF) process is investigated. Two sources of heat are employed: a heated printbed and a LED-based interlayer heater (DEMEX), both individually and in combination. Substrates are also modified with a neat LM-PAEK film. T-pull-off tests are used to quantify the interfacial strength and fracture mode analysis distinguishes adhesive, mixed, and cohesive failures. Results show that interfacial trength increases dramatically with the substrate surface temperature. The highest values (40 MPa) are obtained only when the printbed and DEMEX heaters are used in combination, achieving substrate surface temperatures of 300 °C. Failure modes shift from adhesive to predominantly cohesive at these temperatures, indicating effective fusion bonding. These findings demonstrate that a dual-heat source strategy is a reliable means of achieving robust overprinting bonds in semi-crystalline thermoplastic composites and paves the way for fully integrated hybrid laminate structures.