Papers by Keyword: Selective Laser Sintering (SLS)

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.

Abstract: In contrary to the traditional injection molding process, the selective laser sintering process offers a nearly unlimited freedom of design. However, the dimensional accuracy of an SLS part is significantly influenced by the process, the material and its design. In order to achieve high accuracy, the parts need to be repositioned, parameters readjusted and parts consistently rebuilt in an iterative process. In industry this process leads to enormous consumption of process time and polymer powder.Increased dimensional inaccuracy is often caused by the accumulation of polymer melt and the resulting shrinkage effects. Thus, highly accurate SLS parts can be manufactured using three dimensional, filigree structures in order to replace volumetric part sections. In this paper, the potential of using 3D-structures, for enhancing SLS parts’ accuracy is shown. Thus, influencing parameters, such as positioning, scale, process time and geometry feature are systematically varied. Additionally the effect of adjacently positioned parts influencing the dimensional accuracy shall be investigated.

Abstract: The principle and application of rapid prototyping technology were presented. Several typical rapid prototyping technology were introduced, such as the Stereo Lithography Appearance, Laminated object manufacturing, fused deposition modeling, selective laser sintering, three dimensional spray adhesive technology. The rapid prototyping technology was used in manufacturing, clinical surgical, defense technology, ceramics, dental, and so on. The choke point of rapid prototyping technology application was analyzed, such as molding materials, precision error, and the performance of data sharing software. The future development trend of rapid prototyping technology is prospected also.

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.

Abstract: The paper presents the characteristics of the selected additive technologies SLS - selective laser sintering, 3D Printing - bonding of ceramic powders, PolyJet Matrix - photocuring polymer resins. Procedures and methods for preparing models in the above-mentioned technologies are discussed. The examples of models made during research are described. The solutions covered by the patent application are also presented.

Abstract: The article describes the technology of making thin-walled components and elastic by additive technology SLS using a polyamide powder PA 2200. The characteristics of the selected elements and the results of their strength tests are presented. The research focuses on the anisotropy of the materials in the various models. Printing processes were investigated on surfaces perpendicular and parallel to the axis of the model. Based on measurements of deformation, coefficients of elasticity, and the influence of selected parameters of the printing process, the accuracy of tested elements were determined. Comparing results of the research indicated that there is a significant influence of direction and printing process parameters on elastic properties. Research can be helpful in the future in the design process of elastic and thin-walled components such as springs and bellows.

Abstract: Selective Laser Sintering/Selective Laser Melting (SLS/SLM) is one of Additive Manufacturing (AM) processes that utilize layer by layer powder deposition technique and successive laser beam irradiation based on Computer Aided Design (CAD) data. During laser irradiation on metal powders, melt pool was formed, which then solidified to consolidated structure. Therefore, melt pool is an important behavior that affects the final quality of track formation. The study investigates the melt pool behavior through visualization of the consolidation process during the single track formation on the first layer. In order to understand the transformation process of metal powder to consolidated structure and mechanism involved, high speed camera was used to monitor the process. Yb:fiber laser beam was irradiated on metal powder at maximum power of 150W. The laser processing parameters such as laser power, scan speed and layer thickness were varied in order to investigate their influence on the consolidation process. The result shows the size of melt pool increased with laser power and decreasing with increment in scan speed. Furthermore, with the increase of layer thickness, melt pool formation was unstable with chaotic movement. Significant amount of molten powder splattering was recorded from the melt pool. At high layer thickness also, the molten powder formed spherical shaped and the solidified molten powder failed to wet with the substrate.

Abstract: Based on mechanism of SLS, the scanning speed, laser power, preheat temperature and thickness of spreading layer are main factors to part quality in Selective Laser Sintering(SLS). With manufactured specimen pieces by Molding machine AFS-450, orthogonal experimental design and analysis of variance were adopted to post-treatment. Three indexes, including sintering strength, constriction percentage and sintering density, were studied. So an optimized project can be determined. This work can provide process parameters in SLS for ABS power. It will be of benefit to improve the part dimensional precision and strength.

Abstract: This paper presents an experimental study about the influence of the Selective Laser Sintering process parameters on the surface and cross-section porosity of parts sintered in polyamide PA2200 material two times recycled. Using of recycled powder affects the part structure and mechanical properties. Therefore, the paper aims to develop a suitable strategy to improve the part structure by controlling the most important SLS process parameters. The main process parameter whose influence was studied is the energy density of the laser beam. Special sample was designed and prototyped using EOS P100 prototyping machine. Three repetition jobs with different energy density of the laser beam were performed. Scanning Electron Microscopy was used to analyze the surface morphology and microstructure of the sintered benchmark parts. The relationship between the SLS parameters and part quality will extend the use of PA2200 recycled material.

Abstract: Material removal, forming, casting and joining are the established manufacturing approaches and processes based on these approaches are being practiced even in modern industries with appropriate automation. Layer by layer material deposition method to produce prototypes from a solid model is relatively new and was developed during last 10-15 years of 20th century. These processes were named as Rapid Prototyping (RP) or Solid Freeform Fabrication (SFF). Today there are many commercial RP system and most of these able to deposit liquid or solid/powder polymer based materials. Some systems are also able to deposit blends of polymer and metal or ceramic. Latest trend in this area is to deposit metals or alloys with variable composition and hence to produce functionally graded material. This paper describes in general the details related to RP processes, data preparation, and various commercial RP technologies. The article also discusses applications these processes.