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Manufacturing parameter influence on FDM polypropylene tensile properties
Aleksa Milovanović,Zorana Golubović,Snežana Kirin,Tomáš Babinský,Ivo Šulák,Miloš Milošević,Aleksandar Sedmak 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11
Polypropylene (PP) is a relatively new material in fused deposition modeling (FDM) technology. The main feature of this material is its ability to significantly elongate under applied load, unlike any other thermoplastic material used in FDM technology. Not much research has been conducted on this FDM material so far, hence, the subject of this paper is the investigation of printing parameters’ influence on PP tensile properties. Targeted parameters are layer height, infill density, and the orientation of raster lines, resulting in four different manufacturing regimes. To have a better insight into the experimental results, the data are analysed using ANOVA statistical method with Tukey HSD post hoc test. Obtained statistical results have proven the printing parameter’s influence on tensile results, emphasizing the influence on elastic modulus. Here, Tukey test results show the maximal number of homogeneous subsets evidencing that all printing parameters have an influence on elastic modulus values.
Mihajlo Popović,Miloš Pjević,Aleksa Milovanović,Goran Mladenović,Miloš Milošević 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2
High demand for part customization shifts industries toward AM technologies. Part customization in high-volume manufacturing is developed to its limits, whereas low-volume production using AM is still economically unjustified. FDM technology is quite common in lowvolume AM production, but the main issue is poor printing parameter optimization which may result in insufficient final part quality. The subject of this paper is the experimental determination of the optimal parameters for the PLA polymer FDM parts, focusing on nozzle temperature and printing speed. Part geometry and mechanical properties are evaluated for the temperature range of 170-210 °C and speeds of 40, 80, and 120 mm/min. Roughness measurements for part geometrical accuracy assessment and tensile tests for mechanical property estimation have shown the clear advantage of 190 °C and 40 mm/min over the other parameter combinations. However, for higher FDM process productivity 80 mm/min speed may also be considered with 190 °C.
Ivo Šulák,Tomáš Babinský,Alice Chlupová,Aleksa Milovanović,Luboš Náhlík 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3
This study investigated the effect of building direction (BD) and three-step heat treatment on the microstructure and mechanical properties of a nickel-based superalloy Inconel 939 produced by additive manufacturing (AM), and it revealed the differences to the conventional cast superalloy. Tensile specimens were printed in horizontal and vertical BDs, and tensile tests were performed at room temperature, 700 °C and 800 °C. Thorough microstructural scrutiny conducted through light and electron microscopy revealed microstructural differences between AM and cast Inconel 939. The columnar grain structure with a preferential orientation of <001> was typical for AM alloy, whereas polyhedral grain without any specific orientation was typical for cast alloy. Experiments showed that the AM material had much better mechanical properties than the cast material. Heat treatment resulted in a formation of a fine dispersion of spherical γ′ nanoprecipitates, triggering a considerable increase in tensile strength and a drop in ductility.
Printing orientation influence on tensile strength of PA12 specimens obtained by SLS
Ivana Jevtić,Zorana Golubović,Goran Mladenović,Filippo Berto,Aleksandar Sedmak,Aleksa Milovanović,Miloš Milošević 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11
Selective laser sintering (SLS) is one of the additive manufacturing technologies dedicated to the production of high-quality parts with complex geometries. Here, polyamide 12 (PA12) is a commonly used material, for manufacturing parts with sufficient mechanical and thermal properties. In SLS, many manufacturing parameters have an effect on the mechanical properties of final parts. Even the decision regarding the orientation of a part in a powder bed may have a significant effect on the mechanical properties. In this research, the influence of horizontal (H) and vertical (V) printing orientations on the ultimate tensile strength (UTS) of fabricated PA12 specimens are examined. Our research findings show that H specimens exhibit larger deformations and smaller UTS value scatter in comparison with V specimens. Also, worth pointing out is the fact that V-oriented specimens have a higher elastic modulus. One can assume that the sintering process is more effective in V specimens, due to a more uniform laser beam trajectory than in the H specimens’ case.