Papers by Keyword: Selective Laser Sintering (SLS)

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Authors: Fwu Hsing Liu, Yunn Shiuan Liao
Abstract: This article proposes a rapid prototyping apparatus of selective laser sintering for forming silica ceramic green parts. The main differences between the proposed and other RP processes for forming ceramic part are the slurry material used to obtain fine layer thickness and the capability of constructing support structure to increase the dimensional accuracy of the workpiece having an overhang. The RP apparatus developed by us comprises a laser scanning system, a material paving system, and a computer control system. A CO2 laser is adopted to scan over a mixture made of a silica sol and silica powder. The silica sol acts as a binder to gel the silica powder together, which forms a 3D object using laser gelation method. A series of experiments were carried out to obtain the optimal process parameters. An SEM is employed to analyze the microstructure of the ceramic part. It has been found that the smallest layer is of 100 μm thick. The results show that both the accuracy of the material paving mechanism and the optimal process parameters can fulfill the requirements of the RP processes.
Authors: Arash Gobal, Bahram Ravani
Abstract: Selective Laser Sintering (SLS) has recently become one of the fastest growing additive manufacturing processes due to its capability of fabricating metal parts with high dimensional accuracy and surface quality. Physical modeling of this process plays an important role in properly controlling the process parameters of the process. In this paper, we present a 3 dimensional, adaptive discrete element method for simulation of the SLS process on personal computers. The presented method models the laser-powder interaction at particle level, achieving high simulation accuracy while adaptively increasing the discrete element size as local temperatures drop inside the powder bed for improved efficiency. Numerical shape functions are developed for calculating individual particle temperatures at any point during the simulation. Results show that this physical model improves the runtime significantly in virtual simulation of SLS process without loss of simulation accuracy.
Authors: Jie Liu, Yong Qiang Yang, Jian Bin Lu, Xu Bin Su
Abstract: This paper presents an Object-Oriented class library for scanning path generation in SLS/SLM (Selective Laser Sintering/Selective Laser Melting) process. The classes in the library meet the minimal requirement for the scanning path generation. Specially, in order to take advantage of the Multiprocessor technology and save the generation time, parallel computing is considered in the class library. At last, an application was developed using the class library and an experiment is provided to verify the feasibility of the parallel computing algorithm in the library.
Authors: Feng Chen
Abstract: Typical molding methods-Selective Laser Sintering (SLS) were presented on the basis of principle, formation, development of RPM(Rapid Prototyping and Manufacturing). Take mobile front cover as the example, the process of making sample used the method of SLS was introduced.RPM technology for rapid product development model, not only can improve the design quality and shorten the trial period, and can be modified at any time by CAD and re-validation, which has strong market competitiveness. RPM is a multi-disciplinary in a modern manufacturing techniques, will be more widely used in areas such as new product development. In short, rapid prototyping technology will be developed into a kind of technology can be adopted widely in enterprise, bring huge economic benefits to the enterprise and society.
Authors: Yi Fu Shen, D.D. Gu, Y.F. Pan
Abstract: Balling process in selective laser sintering of 316 stainless steel powder was investigated. It showed that the balling phenomenon was ascribed to the higher liquid viscosity and surface tension effect during laser sintering. The effects of laser power and scan speed on the balling initiation was studied. It was found that increasing laser power and scan speed within a moderate range can reduce balling effect. However, care should be taken to control laser powers and scan speeds that can be used since their excessive increase may give rise to detrimental effects.
Authors: Qing Song Yan, Xu Xiong, Gang Lu, Hong Wan, Can Cheng Liu, Fang Wang, Xun Zou
Abstract: The dimensional accuracy of shells and binders of investment casting which incorporation with selective laser sintering is investigated. The results show that the dimensional accuracy of colloidal silica is higher than that of ethyl silicate, and the dimensional variation rate of investment casting shells produced with colloidal silica is much lower than ethyl silicate shells. Moreover, colloidal silica possesses better performance on environmental protection and production cost control. These indicate that the comprehensive properties of colloidal silica are better than that of ethyl silicate. Meanwhile, the average dimensional variation rate of the single colloidal silica shell and the ethyl silicate-colloidal silica alteration shell was almost identical and it was much lower than that of the other shells which were produced in this study. This means two kinds of shells are optimized in all five types of shells studied in the aspect of dimensional accuracy. The unique properties of two shells show clearly direction to choose the type of shell.
Authors: Shao Jiang Lin, Sai Yu Wang
Abstract: This work compared the densification behavior and pores evolution of two kinds of samples (15% and 35% initial porosity stainless steels parts) prepared by selective laser sintering. The results show that post microwave sintering process results in an increase of the density of sample. At the low sintering temperature (1200°C, 1300°C), the low porosity can lead to high density in the final sintered sample. As the sintering temperature reaches 1400°C, however, the sample with 35% initial porosity could be sintered to the higher final density than that of the sample with 15% initial porosity. The results also indicate that the initial porosity has a great effect on the number of pores, pore size, pore shape and the distribution of pores during post sintering process.
Authors: Saeed Daneshmand, R. Adelnia, S. Aghanajafi
Abstract: In this study, the ability of Selective Laser Sintering (SLS) Technology for production of wind tunnel testing models are evaluated. It has been undertaken to determine the suitability of the Model constructed with SLS method in subsonic and transonic wind tunnel testing. Two models were evaluated in this study. The first model was fabricated from aluminum 5086-H32 by a CNC machining technique. The other model had the same section but was fabricated by the selective laser sintering (SLS) process. Aerodynamic characteristics and times as well as costs of both models were measured in 0.3 to 1.2 Mach and the results were compared. The longitudinal aerodynamic data and the normal force data obtained from SLS model showed good agreement with data obtained from the aluminum model. The greatest difference in the aerodynamic data between two models is the total axial force. The time and the cost of production are considerably reduced with use of SLS model.
Authors: Won Hee Lee, Dong Soo Kim, Young Jin Ahn, Byung Oh Choi, Kyung Hyun Choi
Abstract: In order to develop more elaborate and speedy system for large objects than existing selective laser sintering (SLS), this study applies a new selective dual-laser sintering process. It contains a 3-axis dynamic focusing scanner system for scanning large area instead of the existing fθ lens. As sintering parameters, the sintering temperature, the laser beam power and the layer thickness have a great influence on sintering of the polymer and metal powder. This paper will address the development of a solid freeform fabrication (SFF) system employing the dual laser system. Experiments were performed to evaluate the effect of a scanning path and to fabricate the large-sized object.
Authors: Qiang Zhang, Fu Rong Liu, Ji Min Chen
Abstract: In this paper the research focused on the viability of using the selective laser sintering (SLS) technique for creating tissue engineer (TE) scaffolds. A biocomposite blend comprising polylactic acid (PLA) and hydroxyapatite (HA) was used in the research to study the feasibility of the blend to develop scaffolds. The biocomposite blends obtained via physical blending were subjected to laser sintering to fabricate test specimens. The test specimens were characterized using scanning electron microscopy (SEM) and the components before sintering and after sintering were analyzed by infrared spectrophotometry (IR). The results obtained ascertained that SLS-fabricated scaffolds have good potential for TE applications
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