The use of fibre-reinforced thermoplastics gives novel opportunities for the automated manufacturing of cost-effective lightweight structures on a large scale. Especially the combination of different material configurations in one component offers a promising approach for weight reduction. For this, different semi-finished products like injection moulding compounds, pre-consolidated thermoplastic composite (TPC) sheets or hybrid yarns are established and commercially available. They can be used to produce highly integrated multi-component structures with a combination of torsion- and bend-resistant hollow structures, flat construction elements and three-dimensional knot structures. Therefore, in a two stage process, hollow profiles are pre-manufactured from braided hybrid yarns by blow-moulding and afterwards combined with TPC-sheets and overmoulded by an integrated injection moulding process. During this overmoulding process, the hollow profile must be in cold solid state and stabilised by a supporting structure from the inside to prevent a collapsing under the high injection pressures.
In order to optimally exploit the lightweight potential of these highly complex structures, the interfaces between the individual components must be considered more closely. However, it is known from prior art, that high strengths can only be achieved during overmoulding if the surface of the composite component is completely molten (warm-warm). Hence, for the efficient integration of thermoplastic hollow profiles a surface pre-treatment is necessary to realise adequate bond strengths. The present paper presents experimental studies on the bond strength between different thermoplastic semi-finished products. Both warm-warm joints and warm-cold joints are investigated. For the warm-warm connections, the influences of the preheating temperature are considered in detail. For the warm-cold tested specimens, the effects of both chemical and physical pre-treatment methods are investigated. Both single-lap-shear (SLS) specimens and special rib specimens are used for the examinations.