Study On Optimization Of Molding Process Based On Selective Laser Sintering Of Polystyrene

Polystyrene has become a commonly used polymer material for Selective Laser Sintering(SLS)due to its wide application and good processability.Many investigations on the sintering molding of polystyrene have been conducted by domestic and foreign researchers.However,few systematic studies on the whole molding process and post-treatment were carried out.Different process equipment and experimental conditions would also lead to great differences in molding.This paper studied the forming process of selective laser sintering of polystyrene.Based upon the experiments and numerical simulation,the optimization of the molding process was completed.The main contents of this paper are as below:(1)Based on literature investigation and related experiments,the preheating temperature was set to 85?.Orthogonal experiment was used to analyze the effects of laser power,scanning speed,layer thickness and scanning interval on sintered parts.Subsequently,the influences of different molding process parameters on the dimension,warpage and sintering density of the sintered parts were discussed.The results show that the scanning speed and laser power have a significant effect on the part dimension of the length and width.The dimensional accuracy and warpage in the thickness direction of the part are significantly affected by the thickness of powder layer.Besides,the effects of scanning speed and scanning interval on sintered density are also obvious.The optimization of the sintered part is completed by optimizing the process parameters and design size.(2)A three dimensional finite element thermal model based on ANSYS software was established to study temperature variations by simulating the sintering process of polystyrene.According to the process characteristics of SLS,ANSYS parametric design language(APDL)was employed to control the scanning path,laser power and other parameters.Then the temperature field of SLS for single-layer polystyrene was analyzed.By changing the model size,the corresponding temperature field was researched further.According to the results of numerical simulation analysis and printing experiments,the micromechanism of the molding process was analyzed and studied.Finally,MOLDFLOW software was used to analyze filling time,flowing front temperature,etc..The molding characteristics of polystyrene under different technological conditions were observed and analyzed.And improved schemes were also put forward for the 3D equipment used.(3)Post-processing included two experimental schemes,infiltrated with wax and epoxy resin.Based on the related experiments of sintered parts,the influence of preheating temperature and wax-infiltrated temperature on the dimensions of the fabricated parts was explored.In addition,the experiments infiltrated with wax were performed again to discuss the surface quality and wax thickness of the parts.The results show that the wax thickness of the parts gradually decreases with the rising of the temperature.And the thickness of wax layer can be controlled by changing the wax-infiltrated temperature.Two epoxy resin solution systems were configured,and five groups of experiments were respectively set under each epoxy system.The epoxy resin solutions were used to infiltrate and densify the parts.It is found that the parts with 593 curing agent has higher tensile and bending properties than that of the T31 curing agent.In this paper,the sintering molding process and post-treatment of polystyrene were investigated.The sintered parts of polystyrene were well completed by related equipment and optimized process parameters.And the post-processing was utilized for improving the mechanical properties of the parts.The research results and methods can provide theoretical basis and data support for further experimental research and practical application.