An investigation on conformal cooling in plastic injection moulding

One of the most important features of mould cooling in injection moulding is the provision of suitable and adequate cooling arrangements. For many years, mould designers and researcher have been trying to improve the performance of cooling system, despite the fact that cooling system complexity is physically limited by fabrication capability of conventional straight drilling methods. This research presents a comprehensive investigation on the application of conformal cooling channels in injection moulding for different cross sectional shapes, positions and diameter by endeavoring which conformal cooling configuration gives the best results in comparison with conventional cooling channels. Mould design with efficient cooling channels, comprehensive finite element analysis and flow simulation have been performed for different plastic parts with Pro/Engineer, ANSYS and Autodesk Moldflow Insight simulation software. Structural-thermal finite element analysis has been performed for two different types of industrial plastic part moulds with conventional, conformal and bimetallic conformal cooling channels to study the robustness and longevity of the conformal cooling channel moulds in comparison with conventional cooling channel moulds. Fatigue life of the mould with different cooling channel configuration and different materials has also been predicted using high cycle fatigue formulas and stress analysis results. Laser direct metal deposition (DMD) rapid manufacturing technology has been used to fabricate conformal cooling channel in injection mould for experimental validation of the results obtained by numerical modeling. Experimental verification has also been done for a test plastic part using conventional, conformal and bi-metallic cooling channel moulds, which have been manufactured by conventional computer numerical control machining process for mini injection moulding machine. Finally, hardness test has been done with Shore D hardness testing machine for test plastic parts which have been produced with conformal and conventional cooling channel mould. In conclusion, simulation and experimental verification show that with optimal cross section, diameter and position, the conformal cooling channel moulds reduce significant amount of cycle time as well as improve the quality of plastic parts produced by injection moulding process.