In-mould coating (IMC) is an environmentally friendly alternative to painting for injection moulded plastic parts. IMC is carried out by injecting a liquid low viscosity thermoset material onto the surface of the thermoplastic substrate while it is still in the mould. The coating then solidifies and adheres to the substrate. The IMC process is being integrated with conventional thermoplastic injection moulding to improve the part surface quality and to protect it from outdoor exposure. In a previous paper, we presented a Hele-Shaw based mathematical model to simulate the coating flow during the IMC process assuming the coating to be a Newtonian fluid. It has been shown that the coating behaves like a shear thinning fluid. In this paper, a power-law viscosity model is employed to describe the Theological behaviour of the coating material. The continuous deformation of the thermoplastic substrate caused by the coating injection is analysed by means of the PVT relationship of the substrate. The corresponding model is solved using the control volume based finite element method to predict the fill pattern and pressure distribution during the coating flow. The predicted results are compared to experimentally obtained fill patterns. The need to include the 'edge effect' is also discussed.
展开▼
