On the need to better control tooling in prepreg Automated Fibre Placement (AFP) deposition

Efficient tack between ply and tooling is crucial for achieving accurate, defect-free and reliable placement of prepreg in Automated Fibre Placement (AFP). However, current industry practices for choosing AFP tooling's material almost never account for this. The present contribution makes the scientific case for a more careful accounting of tack in the choice of AFP tooling material. Employing a modified probe test method, tack between prepreg, specifically Hexcel IM7-8552, and various tool surfaces was characterised. The effect of the roughness and material types on tack and its further influence on AFP deposition was investigated. The study shows that different materials have varying traction-separation behaviour, with metals showing higher values than composite materials. Release agent-treated samples exhibited the lowest tack, making them unsuitable for directly used in AFP. It is concluded that, by better considering tack, engineers can tailor their tooling material to enhance the quality and reliability of the deposition process.