Warpage and shrinkage control are important factors in proving the quality of thin-wall parts in injection modeling process. In the present paper, grey relational analysis was used in order to optimize these two parameters in manufacturing plastic bush of articulated garden tractor. The material used in the plastic bush is Derlin 500. The input parameters in the process were selected according to their effect on shrinkage and warpage values, melt temperature, mold temperature, injection rate, injection pressure, and packing pressure. Then, the Taguchi method was applied to design the experiments, and through the use of Mold Flow software injection molding process was simulated based on these experiments and the input parameters. Based on the results obtained from the simulation, the input parameters were analyzed in three levels using grey relational analysis. Then, analysis of variance and confirmation tests were carried out on the output of grey relational analysis to predict the optimum values of the input parameters and to calculate the dimensional changes of the plastic bush. Gaining these values, the plastic bush sample was manufactured, and its 3D point cloud model was generated by a scanner. At the end, by generating 3D solid model of the plastic bush its dimensional features were studied. The comparison of the warpage and shrinkage values between grey relational analysis and 3D CAD model indicates the precision of the method in controlling and measuring these two parameters.
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