Study On Prediction Of Shrinkage For PS Parts By Selective Laser Sintering

Selective Laser Sintering(SLS)is a kind of additive manufacturing method with high forming efficiency,high precision and high forming quality,it also has the advantages of manufacturing complex parts,free-standing,simple process and wide selection of the materials,which has become one of the research focuses in additive manufacturing industry.In order to reduce the shrinking deformation of polystyrene(PS)parts prepared by SLS,a prediction model of size shrinking rate and optimize process parameters were established by combining the finite element numerical simulation and experiment,this study will propose the effective ways and methods to reduce of the dimensional shrinkage.First of all,based on the forming process of SLS process,the error sources of SLS forming parts are systematically analyzed,and the composition and causes of the main error sources 'material forming shrinkage' are specifically discussed and analyzed.On this basis,the process parameters affecting sintering shrinkage are qualitatively analyzed.Secondly,the shrinking size of the molded part is taken as the prediction object,and the thermal physical parameters of PS powder material are taken as the intermediate parameters between the process parameters and the shrinking size.The temperature field distribution under different process parameters is simulated and analyzed by using the ANSYS simulation software.According to the influence of temperature on the thermal physical parameters of the PS material,the shrinking size is predicted theoretically,and the accuracy of the was prediction verified by SLS sintering experiments.Finally,in order to reduce the size shrinking of the formed parts,the influence of laser power,delamination thickness and scanning speed on the shrinking size was analyzed by the single factor analysis.Based on the prediction results and the single factor analysis results,the orthogonal experiments were carried out,and the signal-to-noise ratio and gray correlation degree are used to optimize the process parameters.On the basis of optimizing process parameters,the way of dimension error compensation is found and the effectiveness of the method is verified by experiments.This study provides a new idea and method for effectively reducing the size error of SLS forming parts,simplifies the process of process parameter optimization,improves the quality of SLS forming parts,and accelerates the application of SLS technology.