Modeling the adhesion bonding mechanism in overmolding hybrid structural parts for lightweight applications

Reducing vehicle weight to decrease energy consumption and engine emissions is one of the major objectives of the automotive industry today. This goal is mainly achieved by developing new manufacturing technologies for structural lightweight components, such as the hybrid injection molding/composite forming process, which involves preforming a thermoplastic composite laminate and overmolding it to add ribs, attachment points and other features. High part lightness, short cycle times and high degree of automation have recently made this technology an effective solution for the manufacturing of automotive interiors, including door side-impact beams and front ends. In this paper a model of the adhesion bonding mechanism between the overmolded reinforced thermoplastic and the formed composite sheet is proposed, and its dependence on the main process parameters is investigated. The model has been developed conducting experimental tests and eventually validated by means of a significant case study.