Induction heating for automated fibre placement tools

Abstract

While Automated Fibre Placement is a versatile process for manufacturing composite parts, the rapid heating and cooling inherent to the process results in high temperature gradients. When thermoplastic composites with a semi-crystalline matrix are used, high cooldown rates also impede crystallisation processes. Heated toolings can alleviate the problem, but including heating technology in toolings with complex geometries while ensuring a homogeneous temperature distribution is often difficult and requires tools with high thermal mass, which also require more energy to heat and can only achieve slow heating rates. By using flexible induction coils fixed to a thin ferromagnetic metal sheet, a double-curved tooling with induction heating was developed and successfully used in manufacturing composite skin panels. Compared to traditional heating technology, higher heating rates and better energy efficiency could be achieved. The process was accompanied by AFP simulation to predict process induced warping, achieving this with 90% accuracy in the planar regions of the tooling.