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.
Experimental research in both medical sciences and material science rely in many situations on a reduced quantity of available data, due to limited number of patients or high costs of samples. Some statistical data manipulation methods are discussed regarding their applicability, information content, value and limits. A special attention is given to the extreme values eliminated by the GRUBBS test. The necessity of the elimination of the extreme values is demonstrated.
The paper presents a study on how the orientations of the building layers are influencing the mechanical properties and the structure of the part. In this way, a cylindrical part was built in three positions: vertical, horizontal an 45 degrees using EOS Formiga P100 machine. The samples were both mechanical tested on compression and subjected to metallographic analysis. The compression tests reveal the particular behaviour of the samples, according to the layer orientation in relation to direction of the load. The metallographic analysis shows structural aspects of alumide, the presents of pores, the shape and orientation of the aluminium particles. The study concludes that by using various orientations of the part in the building process, we may establish a compromise relation between the geometrical accuracy of the part and its mechanical properties.
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