Design and optimisation of conformal cooling channels in injection moulding tools

With increasingly short life span on consumer electronic products such as mobile phones becoming more fashionable, injection moulding remains the most popular method for producing the associated plastic parts. The process requires a molten polymer being injected into a cavity inside a mould, which is cooed and the part ejected. The main phases in an injection moulding process therefore involve filling, cooling and ejection. The cost-efficiency of the process is dependent on the time spent in the moulding cycle. Correspondingly, the cooling phase is the most significant step amongst the three, it determines the rate at which the parts are produced. The main objective of this study was to determine an optimum and efficient design for conformal cooling/heating channels in the configuration of an injection moulding tool using FEA and thermal heat transfer analysis. An optimum shape of a 3D CAD model of a typical component suitable for injection moulding was designed and the core and cavity tooling required to mould the part then generated. These halves were used in the FEA and thermal analyses, first determining the best location for the gate and later the cooling channels. These two factors contribute the most in the cycle time and if there is to be a significant reduction in the cycle time, then these factors have to be optimised and minimised. Analysis of virtual models showed that those with conformal cooling channels predicted a significantly reduced cycle time as well as marked improvement in the general quality of the surface finish when compared to a conventionally cooled mould.