The Method Research Of Injection Molding Parameters Optimization Based On Multi-objective PSO Algorithm

Injection molding is one of the most important method of plastic molding, its setting of process parameters can directly affect the quality of plastic parts. It is necessary to improve the quality of injection parts by optimizing the process parameters of injection molding.The warpage and shrinkage,which are the most common defects in injection molding, was selected as the research object, the main reasons cause these two kinds of defects was analysed, a set of method combined numerical simulation with modern optimization design was put forward to optimize the process parameters in the injection molding, in order to reduce the warpage and shrinkage of plastic parts at the same time. Firstly, a numerical simulation about warpage and shrinkage of auto reflectors was conducted by using Moldflow. Based on the analysis results and the related material, the main factors which influence plastic parts were founded out. Then, a Box-Behnken design by using Design-expert software was conducted, we selected mold temperature, melt temperature, holding pressure and dwell time as experimental factors, selected warpage and shrinkage as target variable. Then, two equations about warpage and shrinkage with process parameters were established by using the response surface method. The least squares method was used to solve the two response surface equation to obtain the minimum value of warpage and shrinkage respectively, and their corresponding optimal process parameters sequence were also obtained. In order to achieve the multi-objective optimization, a multi-objective particle swarm optimization algorithm based on target weighted (WAQPSO) was used to solve that two equations, thus a series of Pareto optimal solution which can make warpage and shrinkage reaches each minimum value were obtained. Then, a Pareto optimal solution was selected to verify the results of WAQPSO algorithm by using Moldflow. Finally, a test to the shrinkage of plastic parts had been conducted, which proved that numerical simulation combined with modern optimization design could performs well in multi-objective optimization of plastic parts, and it can be applied to practical production.