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Overmoulding of consolidated fibre-reinforced thermoplastics - increasing the bonding strength by physical surface pre-treatments

: Liebsch, Alexander; Koshukow, Wikentij; Gebauer, Jana; Kupfer, Robert; Gude, Maik

Fulltext ()

Procedia CIRP 85 (2019), pp.212-217
ISSN: 2212-8271
Conference on Composite Material Parts Manufacturing (CCMPM) <2, 2019, Sheffield>
Bundesministerium für Bildung und Forschung BMBF (Deutschland)
Bundesministerium für Bildung und Forschung BMBF (Deutschland)
Bundesministerium fur Wirtschaft und Energie BMWi (Deutschland)
Journal Article, Conference Paper, Electronic Publication
Fraunhofer IWS ()
composite; surface modification; laser micro machining; joining; injection moulding; fibre reinforced plastics

Fibre-reinforced thermoplastic materials enable an automated and economical manufacturing of lightweight structures in series-production. By combining different material-configurations, highly stressable components can be designed. Previous studies have shown that the combination of continuous fibre-reinforced hollow profiles and injection moulding compounds is suitable even for crash-relevant automotive parts. During the overmoulding process, the pre-consolidated hollow profile must remain cold in order to withstand high injection pressures. However, this leads to a poor adhesion between the profile and the overmoulding material. To increase the bonding strength, the interface can be pre-treated using laser and plasma technology. In this work, fibre-laser and atmospheric pressure plasma treatment are applied to glass fibre reinforced polyamide 6 composite (PA6/GF) sheets. The resulting surface properties are investigated by wettability and microscopy analysis. Afterwards, single-lap-shear specimens and special rib specimens are manufactured by overmoulding the sheets with PA6-66/GF bulk material. The resulting bonding strengths are characterised in tensile shear tests as well as pull-off tests of the ribs. The effects of different pre-treatment parameters on the bonding strength are analysed. Additionally, the effect of sheet temperature on the bonding strength is investigated, also including specimens without pre-treatment. Finally, the results are discussed with regard to the surface treatment of composite hollow profiles, considering bonding strength, manufacturing environment and processing times.