Study On Numerical Simulation Of 3D Temperature Field During Selective Laser Sintering Polymer-coated Metal Powder

Selective laser sintering (SLS) is one of rapid prototyping (RP) technology with maturity and commodity, which has widely prototyping materials and having no use for the clamping fixture and mould. The key factor of manufacturing precision is the distribution of temperature. However, during the laser sintering process, the complex variable temperature fields always brings the metal parts deformation and shrinking, which can not meet the engineering demand. Therefore, based on the numerical simulation of sintering temperature fields, the high precision metal prototyping parts were prepared by the proper laser sintering process parameters. The content and result of the article are as follows.In this paper, the mechanism of selective laser sintering polymer-coated stainless were studied. Then, the different process parameters have been investigated, such as laser power, scanning velocity, preheating temperature and powder spreading density, to the effects of heat consolidation process under laser scanning processes.Based on thermal conductance theory and finite element method (FEM) of temperature fields, the FEM model of selective laser sintering temperature fields was provided. The general data structure of FEM model was extracted, and the heat analysis operating model was designed. With the application of limit differentials, the discrete time domain was realized. With the Galerkin weighted residual method, the mathematical model and the flow chart of temperature field calculation were provided.BP neural network arithmetic forecasted the thermo-physical properties of polymer-coated stainless powder. With the forecasting thermo-physical properties, the effects of different processing parameters on the temperature field of polymer-coated stainless thermal consolidation process and the consolidation field were analyzed. Through 3D temperature fields FEM simulation, the effects of prototyping parameters on sintering parts were studied. Based on experimental validating and numerical simulation, the simulation results have an agreement with the experimental results. The proper process parameters (23W laser power, 75℃preheating temperature, 1300 mm/s scanning velocity, 0.15mm spreading powder depth) were determined, and some metal parts with different three-dimensional shape were manufactured.At last, the author gave a prospect of the FEM simulation on SLS temperature fields and its application to sinter polymer-coated metal parts.