Multiple component moulding (MCM) is one of the great methods to fabricate the modern injection products. Due to many procedure combinations, it is very difficult to know the detailed process. Besides, because of its complicated nature and the unclear physical mechanism, using trial-and-error method cannot realize and manage the mechanism effectively. In this study, we will review various MCM technologies, including over-moulding, and co-injection moulding, and study these two applications in more details. Results show that the product geometries, process condition, and moulded materials will affect the product quality. The physical mechanism of warpage in a sequential over-moulded part is due to the unbalance between the volumetric shrinkage during filling/packing and the thermal unbalance from cooling. The warpage behavior for co-injection moulding is more complicated because of the uncertain interface. However, one of the keys to manage the warpage is the control of the core penetration.
International Journal of Materials and Product Technology 52(1-2), pp.118-142