Recent developments on the overmolding process for the fabrication of thermoset and thermoplastic composites by the integration of nano/micron-scale reinforcements

Overmolding process is one of the growing advanced technologies for fabricating lightweight composite structures used in the aerospace and automotive industries. This technology enables integrating multiple types of reinforcements from macro- to nano-scale in thermoplastic and thermoset matrices and assembling of dissimilar polymeric materials. Besides, this process is well suited to a digitalization of advanced composite manufacturing for complex geometries with outstanding performance and high adaptation to multifunctionality. The present review aims to cover the recent developments in the design and fabrication of thermoset- and thermoplastic-based composite systems via overmolding process under (i) multi-material injection molding and (ii) insert molding technologies with the employment of nano/micron-scale reinforcements. Multi-material injection molding (or over injection) is investigated by considering two or more thermoplastic polymeric systems in a single mold to obtain high structural performance and bonding quality. On the other hand, the insert molding process is evaluated through matrix and reinforcement types to understand the strength and structural integrity during composite manufacturing. The main bottleneck of adhesion strength in the overmolding process is elaborated with the discussion of distributive approaches and offers a new perspective in producing multi-functional composites in a single-step process with design tools