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Abstract: This study investigates the predictive modelling of weld bead geometry in wire arc additive manufacturing (WAAM) through advanced machine learning methods. While WAAM is valued for its ability to produce large, complex metal parts with high deposition rates, precise control of the weld bead remains a critical challenge due to its influence on mechanical properties and dimensional accuracy. To address this problem, this study utilized machine learning approaches—Ridge regression, Lasso regression and Bayesian ridge regression, Random Forest and XGBoost—to predict the key weld bead characteristics, namely height, width and cross-sectional area. A Design of experiments (DOE) was used to systematically vary the welding current and travelling speed, with 3D weld bead geometries captured by laser scanning. Robust data pre-processing, including outlier detection and feature engineering, improved modelling accuracy. Among the models tested, XGBoost provided the highest prediction accuracy, emphasizing its potential for real-time control of WAAM processes. Overall, this study presents a comprehensive framework for predictive modelling and provides valuable insights for process optimization and the further development of intelligent manufacturing systems.
Keywords: wire arc additive manufacturing, WA AM, predictive modelling, machine learning, weld bead geometry, XGBoost
Published in DKUM: 13.03.2025; Views: 0; Downloads: 6
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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: Tema diplomskega dela je bila narediti simulacijo postopka obdelave kovinskega izdelka z robotom. V prvem delu diplomskega dela smo preučevali, kateri postopki so primerni za obdelavo z robotom, kateri niso in zakaj je temu tako. V drugem delu pa je sledila simulacija obdelave z robotom kovinske plošče, ki služi kot premični del Z-osi na CNC usmerjevalniku. Pri tem smo po korakih opisali postopek kako pripraviti delovno celico, orodje in robota ter kako definirati obdelovalne postopke in jih prikazati kot simulacijo. Na koncu so prikazani rezultati simulacije.
Keywords: obdelava z robotom, simulacija, načrtovanje proizvodnega procesa
Published in DKUM: 09.10.2024; Views: 0; Downloads: 19
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Abstract: Tema diplomskega dela je narediti simulacijo postopka brizganja plastike s prelivanjem. Najprej sem zapisal, kaj je postopek brizganja plastike s prelivanjem, kakšne tehnike poznamo, kateri materiali se uporabljajo in na katerih področjih se uporablja brizganje plastike s prelivanjem. V drugem delu diplomske naloge sem naredil simulacijo za brizganja plastike s prelivanjem za ročaj izvijača. Tu sem naprej po korakih opisal, kako sem izdelal celotno simulacijo. Opisal sem tudi, katere nastavitve za simulacijo sem uporabil. Na koncu so opisani in razloženi rezultati začetne simulacije, ki niso bili primerni. Zato sem naredil drugo simulacijo, pri kateri sem spremenil nastavitve in jo potem primerjal z začetno simulacijo.
Keywords: brizganje plastike s prelivanjem, simulacija, čas cikla, primerjalna študija
Published in DKUM: 03.07.2024; Views: 147; Downloads: 37
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Abstract: It is well known that Selective Laser Melting (SLM) does not provide the same mechanical properties in all directions of the part. This is due to the microstructural grain orientation and pore shape in SLM products. Therefore, depending on the direction of the pressure applied to the SLM product, a different manufacturing orientation is required to achieve the best mechanical properties. Changing the microstructural grain orientation is difficult through SLM, but a process to reduce the size and number of the pores can be discovered through different combinations of manufacturing parameters. In prosthodontics, pressure is usually applied in the vertical direction, which leads to compression and bending of crowns with bridges. The compressive load can be easily absorbed in the crowns, but the bending force has a significant effect here. Therefore, a product with high tensile strength and high ductility is needed to survive longer. Considering these requirements, this study determined the best parameters for laser processing by SLM method to reduce porosity and improve mechanical strength and ductility of Co-CrW-Si alloy products. The result is a relative product density of 100% for cubic specimens and a yield strength, ultimate tensile strength, and elongation at break of the tensile specimens of 900 MPa, 1200 MPa, and 15%, respectively, obtained in specimen build-up in the Z direction with a laser power of 60 W and a scanning speed of 450 mm/s. Eventually, the best orientation for the production of dental prosthetic elements using the SLM process was determined.
Keywords: cobalt-chromium alloy, dental implant, density, tensile strength, ductility, selective laser melting
Published in DKUM: 03.07.2024; Views: 78; Downloads: 14
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