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Abstract: Knowledge of defect formation mechanisms in the manufacturing process helps improve product quality. In this study, defect formation due to re-melting of each layer in selective laser melting of Ti-6Al-4V demonstrated the physical behavior in the manufacture of metallic parts. The re-melting strategy was based on scanning with low energy density (ED) and increased ED with various combinations of laser processing parameters. The increased EDs and their parameters, namely laser power, scanning speed, and hatch distance, were selected based on the previous research experience by the authors. The concept of selecting a low ED followed by a high ED was to reduce the spattering of the powder material during the process. The low ED caused partial sintering of the powder, while the high ED caused the melting of the material, resulting in different metallurgical properties of the manufactured parts. Densities, pore properties, porosity in the initial layers, surface morphologies, and microstructures in the defective areas of the samples were studied to determine the effects of re-melting. Advantages and disadvantages were found with respect to the range of applications of the products
Keywords: re-melting, pore properties, defect, surface morphology, Ti-6Al-4V, selective laser melting
Published in DKUM: 14.03.2025; Views: 0; Downloads: 2
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Abstract: This study applied a holistic approach to the problem of controlling the temperature of critical areas of tools using conformal cooling. The entire injection molding process is evaluated at the tool design stage using four criteria, one from each stage of the process cycle, to produce a tool with effective cooling that enables short cycle times and ensures good product quality. Tool manufacturing time and cost, as well as tool life, are considered in the optimization by introducing a novel tool-efficiency index. The multi-objective optimization is based on numerical simulations. The simulation results show that conformal cooling effectively cools the critical area of the tool and provides the shortest cycle times and the lowest warpage, but this comes with a trade-off in the tool-efficiency index. By using the tool-efficiency index with non-dominated sorting, the number of relevant simulation cases could be reduced to six, which greatly simplifies the decision regarding the choice of cooling system and process parameters. Based on the study, a tool with conformal cooling channels was made, and a coolant inlet temperature of 20 °C and a flow rate of 5 L/min for conformal and 7.5–9.5 L/min for conventional cooling channels were selected for production. The simulation results were validated by experimental measurements.
Keywords: conformal cooling, injection molding, tooling, additive manufacturing, numerical simulation, non-dominated sorting
Published in DKUM: 05.12.2024; Views: 0; Downloads: 5
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Abstract: When manufacturing complicated products where both material and design play a role, especially thin and curved components, it is difcult to maintain accurate dimensions in Selective Laser Melting. Considering these difculties, this article presents the dimensional errors in the fabrication of Ti-6Al-4V discs and their thermomechanics during manufacturing. Various combinations of laser processing parameters were used to fabricate the 2.00 mm thick discs with a diameter of 5.70 mm. It was found that the thickness shortened and the round shape changed to an oval shape for most of the discs. The thickness decreased along the build-up direction from the bottom to the top and formed a taper that increased with increasing energy density (ED). The horizontal diameter of the discs changed slightly, while the vertical diameters changed remarkably with increasing ED. On the other hand, reducing the laser power resulted in a reduction of the roundness error, while it caused a reduction of the thickness. The hatch spacing signifcantly afected the volume of the melt pool and caused a change in the vertical diameter. The central part of the curved surface of the discs became concave and the concavity increased due to the increasing ED.
Keywords: dimension, Ti-6Al-4V, lase power, scanning speed, hatch spacing, selective laser melting
Published in DKUM: 29.03.2024; Views: 219; Downloads: 9
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Abstract: Diplomsko delo opisuje snovanje procesa po površinskem zaščitnem nanosu v podjetju Hanželič d.o.o.. Reševanje problema smo se lotili tako, da smo izkoristili sredstva, katera so že prisotna v samem podjetju. Cilj je bil, da s čim manj vloženega časa in denarja oblikujemo zanesljiv proces, ki bo kompatibilen z ostalo proizvodnjo. Pri samem snovanju smo upoštevali izkušnje starejših delavcev ter znanje mlajših, kar je pripomoglo k rešitvi problematike naročila.
Keywords: zasnova procesa, vrtanje, serijsko delo, izdelava navojev
Published in DKUM: 28.02.2024; Views: 198; Downloads: 35
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Abstract: V diplomskem delu je zajeta zgodovina podjetja ter opis njihovih izdelkov, opisana je zgodovina in razvoj NC-obdelovalnih strojev, prav tako tudi možnosti programiranja ter postopek obdelave. Diplomsko delo govori predvsem o programiranju CNC obdelovalnega stroja. Predhodni način dela je predstavljal dolgotrajnejši postopek izdelave, saj je bil pred vsako namensko izdelavo panelov potreben ponovni izris in določitev parametrov na samem stroju. Izdelan je bil izris tlorisov, med drugim je bilo izvedeno programiranje CNC obdelovalnega stroja, na koncu pa je sledila še izdelava ter vgraditev panela v bivalno enoto.
Keywords: bivalne enote, CNC, programiranje, izdelava, paneli
Published in DKUM: 07.07.2023; Views: 355; Downloads: 60
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