Research and development of rapid investment casting technology based on SLS

SLS sintering process and material types have a great influence on the sintering results. Most scholars study the influence of different materials and different processes on the sintering results, mainly study the application of different materials and which process can significantly improve the mechanical properties of the sintered parts. Salmoria et al. Mixed styrene with nylon and used CO2 laser SLS rapid prototyping equipment to carry out sintering experiments. The results showed that the best sintering parts could be obtained by changing the proportion of powder, particle size distribution and sintering process parameters.

Mys n et al. Used mechanical and chemical processing technology to prepare isotactic polystyrene powder, and verified the sintering properties of the material. Zheng H et al. Used emulsion polymerization to make nano Al2O3 particles uniformly encapsulate the outer surface of PS particles and to prepare the powders for sintering. The results show that the mechanical properties and internal density of the sintered parts are improved, and the polystyrene is strengthened and toughened. Haseung.Chung In order to improve the mechanical properties of nylon 11 powder, glass beads were added to nylon 11 powder. The optimal process parameters were obtained by optimization. The theoretical and actual tensile modulus and compression modulus of the sintered parts were compared. The results show that the content of glass beads can affect the mechanical properties of the sintered parts.

Liu K et al. Studied the effects of the ratio of glass powder to epoxy resin and sintering process on the properties and microstructure of glass-ceramic by preparing glass-ceramic powder. It was found that with the increase of the ratio of glass powder, the shrinkage of sintered parts decreased and the mechanical strength gradually increased. Dietmar et al. And Athreya et al. Modified the materials and optimized the sintering process, and mainly analyzed the influence of the change of sintering materials and sintering process on the mechanical properties of the sintered parts, especially on the microstructure of the specimens. Dotchev et al. Chose stepped sample as sintering sample and PS as sintering material to study the three-dimensional change in SLS molding process. The results show that the shrinkage of the sample in X and Y directions is linear, while the shrinkage in Z direction is nonlinear. At the same time, two different size compensation methods were proposed.

Senthilkumaran et al. Used nylon as sintering material, mainly studied the influence of scanning mode on the dimensional shrinkage of specimens in different directions, and analyzed the corresponding results. Aiming at the research of SLS forming accuracy, Wang Danni [22] simulated and analyzed the warpage deformation and cylindricity error of the specimen by using finite element method. The experimental results show that the parallel and ipsilateral scanning method is better than the circular scanning method under the cylindrical specimen. Yan Ran et al. Selected PS powder as sintering material, studied the influence of process parameters interaction on the quality of molded parts by response surface method, and established the mathematical model of process parameters and dimensional accuracy, and then obtained the optimal combination of process parameters.

Shi Yusheng and others combined expert system and neural network to optimize the process parameters, and verified the sintering process parameters with standard samples, and selected a BP network model of SLS molding mode. Wang Congjun and others from Huazhong University of science and technology, Yang laixia and others from Xi’an University of science and technology, and Cui Jianfang from North China University all studied the dimensional accuracy of SLS prototype, and studied the influence of junction process parameters on the dimensional accuracy of composites.