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Dimensional deviations in Ti-6Al-4V discs produced with different process parameters during selective laser melting
Snehashis Pal, Marijana Milković, Riad Ramadani, Janez Gotlih, Nenad Gubeljak, Radovan Hudak, Igor Drstvenšek, Matjaž Finšgar, Tomaž Brajlih, 2023, original scientific article

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: 96; Downloads: 2
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Razvoj in izdelava višinsko prilagodljivega stopnišča : diplomsko delo
David Trstenjak, 2023, undergraduate thesis

Abstract: V zaključnem delu smo konstruirali in izdelali višinsko prilagodljivo stopnišče. Za izdelavo tega smo se odločili zaradi neravnega in težko dostopnega terena v podjetju, ki je stopnišče naročilo. Tako smo konstruirali logično razstavljivo stopnišče. S pomočjo računalniškega programa SolidWorks smo izdelali 3D model in vso potrebno dokumentacijo za razrez na cevnem laserju ter CNC plazmi. Znotraj naloge smo izdelek tudi izdelali in dosegli vse zadane cilje.
Keywords: Stopnišče, cevni laser, CNC plazma, CNC upogibni stroj, MIG MAG varjenje.
Published in DKUM: 28.02.2024; Views: 196; Downloads: 14
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Efficiency of laser-shaped photovoltaic cells
Ewa Korzeniewska, Mariusz Tomczyk, Łukasz Pietrzak, Miralem Hadžiselimović, Bojan Štumberger, Klemen Sredenšek, Sebastijan Seme, 2020, original scientific article

Abstract: The main aim of this paper is to analyze the influence of laser shaping of the photovoltaic cell based on its efficiency. The authors described both process of the monocrystalline photovoltaic cell manufacturing, its efficiency, and the possibilities of usage in architecture and the process of creating the photovoltaic cells of unconventional shapes by using laser technology. A method for cutting photovoltaic cells using a fiber laser was presented as well as the parameters of the laser cutting process. The described method allows cutting the massively produced silicon cells according to the predetermined trajectory. Using the proposed process parameters, satisfactory cutting edge quality, and negligible impact of the laser beam on changes in the structure of the photovoltaic cell active layers were achieved. In each cycle of structure cutting, only a small part of the material is removed (from 1 to 2 mikro), and depending on the thickness, the process is repeated from 50 to 300 times. It has been shown that the efficiency of the modified cells depends on the ratio of their surface area to the laser cutting line.
Keywords: photovoltaic cells, efficiency, photovoltaic cell modification, laser modification, silicon cells
Published in DKUM: 15.11.2023; Views: 304; Downloads: 15
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The use of selective laser melting in mandibular retrognathia correction
Andrej Čretnik, Anita Fekonja, 2022, original scientific article

Abstract: Digitalization and additive manufacturing offer new possibilities in the manufacturing of individualized medical and dental products. In the paper we present the results of the first 30 consecutive growing patients (15 males and 15 females), with a mean age of 13.69 years (SD = 1.26), who were treated for mandibular retrognathia (skeletal Class II malocclusion), using fixed sagittal guidance (FSG) appliance, individually manufactured by selective laser melting (SLM). Lateral cephalometric radiographs were taken before (T0) and after (T1) treatment and a detailed cephalometric analysis was performed. with a special focus on a time period for malocclusion correction. The analyzed data were compared with the control group (CG; treated with intermaxillary Class II elastics) that was matched for pretreatment age and pretreatment cephalometric measurements. Both methods were effective in the correction of Class II malocclusion, but the time period of correction was significantly shorter (16.03 ± 1.09 months vs. 20.65 ± 4.12 months) with the FSG appliance. After treatment visual skeletal and dentoalveolar effects were achieved, with statistically significant differences measured in mandibular incisors inclination (0.45° in FSG and 2.84° in CG) and distance (−0.61 mm in FSG and 0.13 mm in CG), in mandibular first molar inclination (−1.07° in FSG and 1.18° in CG) and overbite (−3.82 mm in FSG and −2.46 mm in CG), all in favor of FSG appliance. After the final mean treatment time of 16.03 ± 1.09 months, visual skeletal and dentoalveolar effects were achieved, with significant differences in sagittal (SNB angle, SNPg angle, mandibular length (CoGn) and consequently decrease in ANB angle) as well as in vertical (lower anterior facial height (LAFH) and gonial angle) measurements noted, with no reported complications. As the time needed for malocclusion correction was comparable with the reports in the traditional use of the functional appliance and as all the cosmetical and functional changes in all the treated patients remained stable after a 2-year observational period, growing patients with Class II malocclusion could benefit with this type of treatment. As all the cosmetical and functional changes in all the treated patients remained stable after a 2-year observational period, growing patients with Class II malocclusion could benefit from the treatment with FSG appliance.
Keywords: selective laser melting, individualized manufacturing technology, mandibular retrognathia
Published in DKUM: 18.09.2023; Views: 412; Downloads: 18
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Comparative study of the microstructure and properties of cast-fabricated and 3D-printed laser-sintered Co–Cr alloys for removable partial denture frameworks
Dejan Stamenković, Miljana Popović, Rebeka Rudolf, Milorad Zrilić, Karlo Raić, Kosovka Obradović-Đuričić, Dragoslav Stamenković, 2023, original scientific article

Abstract: Since additive technologies in dentistry are gradually replacing metal casting technology, it is necessary to evaluate new dental constructions intended for the development of removable partial denture frameworks. The aim of this research was to evaluate the microstructure and mechanical properties of 3D-printed, laser-melted and -sintered Co–Cr alloys, and perform a comparative study with Co–Cr castings for the same dental purposes. The experiments were divided into two groups. The first group consisted of samples produced by conventional casting of the Co–Cr alloy. The second group consisted of 3D-printed, laser-melted and -sintered specimens produced from a Co–Cr alloy powder divided into three subgroups, depending on the technological parameters chosen for manufacturing (angle, location and heat treatment). Examination of the microstructure was carried out by classical metallographic sample preparation, using optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) analysis. A structural phase analysis was also performed by XRD. The mechanical properties were determined using a standard tensile test. The microstructure observation showed a dendritic character in the case of castings, while in the case of 3D-printed, laser-melted and -sintered Co–Cr alloys, the microstructure was typical for additive technologies. The XRD phase analysis confirmed the presence of Co–Cr phases (ε and γ). The results of the tensile test showed remarkably higher yield and tensile strength values and slightly lower elongation of the 3D-printed, laser-melted and -sintered samples than those produced by conventional casting.
Keywords: Co–Cr dental alloys, 3D printing, laser melting and sintering, casting, microstructure, mechanical properties, characterization
Published in DKUM: 21.04.2023; Views: 371; Downloads: 32
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Robotska celica za odrez dolivkov z laserjem in merjenje dimenzij brizganega kosa : diplomsko delo
Nejc Derča, 2023, undergraduate thesis

Abstract: Diplomsko delo predstavi načrtovanje in izdelavo robotske celice za obdelavo stekel za luči za avtomobilski bok. Tehnološka problema v diplomskem delu sta odstranitev hladnega doliva iz stekla in zagotavljanje dimenzijsko ustreznih kosov. Diplomsko delo predstavi projekt izdelave zadnjih avtomobilskih luči in zahteve za izdelavo stekla. Izdelava robotske celice zajema brizgalni stroj, robot za manipulacijo kosov, laser za odstranjevanje dolivkov in merilni sistem za dimenzijsko merjenje kosov. Vse dele robotske celice povezujeta medsebojna komunikacija in robotski program.
Keywords: robot, brizganje plastike, laser
Published in DKUM: 13.03.2023; Views: 672; Downloads: 69
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Izdelava mikrostruktur s femtosekundnim laserjem : magistrsko delo
Jure Javornik, 2022, master's thesis

Abstract: Magistrsko delo opisuje sistem za obdelovanje optičnih vlaken in steklenih kapilar, ki je bil izdelan kot razširitev že obstoječega fs laserskega sistema. Opisana sta metoda pridobivanja ultrakratkih laserskih sunkov in teoretično ozadje njihove interakcije z obdelovanim materialom. Nadalje je obravnavan postopek izdelave senzorjev, ki uporabljajo odprto mikrocelico, izdelano iz steklene kapilare na obdelovalnem sistemu. Podani so spektralni odzivi izdelanih senzorjev in rezultati meritev njihovih mehanskih lastnosti. Predstavljeni so mikrofluidni kanali, mikrovijaki in mikroresonatorji, ki so bili izdelani na vrhu optičnega vlakna. Prav tako smo opozorili na zmožnost vpisovanja zrcal v jedro optičnega vlakna s fs laserjem s povzročanjem lokalne spremembe lomnega količnika. Izmerjene so bile optične in mehanske lastnosti vpisanih zrcal pri različnih energijah ultrakratkih sunkov in pri različnih konfiguracijah zrcal. Predstavljena sta bila dva primera uporabe vpisanih zrcal v praktičnih primerih.
Keywords: Ultrakratki sunki, femtosekudni laser, mikrostrukture, vpisana zrcala, mikrocelica
Published in DKUM: 24.10.2022; Views: 515; Downloads: 95
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Primerjava postopkov CNC razreza pločevine za potrebe industrije tovornih nadgradenj : diplomsko delo
Kristijan Muhič, 2022, undergraduate thesis

Abstract: Za doseganje proizvodnih in poslovnih ciljev podjetja, dejavnega v industriji tovornih nadgradenj, je pomembna tudi prva faza proizvodnega procesa, to je razrez pločevine. Diplomska naloga se ukvarja s problemom izbire ustrezne tehnologije razreza pločevine, ki lahko bistveno zniža proizvodne stroške, poveča produktivnost in s tem tudi konkurenčnost podjetja. V diplomski nalogi so predstavljeni različni postopki razreza pločevine, ki so primerne za razrez pločevin, ki se uporabljajo v industriji tovornih nadgradenj. Opisane so prednosti in slabosti posamezne tehnologije, opravljena je analiza tehnoloških značilnosti in opredelitev najprimernejše tehnologije za podjetje, ki se ukvarja s tovornimi nadgradnjami.
Keywords: razrez pločevine, plazma, laser, vodni curek, nadgradnja vozil
Published in DKUM: 28.02.2022; Views: 866; Downloads: 81
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Simulation of Dual-Beam Laser Metal Deposition : magistrsko delo
Matej Kočevar, 2021, master's thesis

Abstract: Laser metal deposition process plays an important role in the coating and additive manufacturing of the components. Implementation of dual-beam process represents a further development and offers the advantage of laser ablation process, which provides exert force on the melt pool and increases absorption properties of the workpiece for laser light in comparison to conventional laser metal deposition processes. The main goal of the present work is to predict temperature distribution on the surface and in the cross-section during a dual-beam laser metal deposition. A better understanding of temperature distribution of the dual-beam laser metal deposition is crucial for analyzing the impact of different process parameters on the process. The prediction of temperature distribution was done using the version 6.14-6 of finite element software ABAQUS/Standard from Dassault Systèmes. The results of the simulations show that the temperature distribution in the case of dual-beam laser metal deposition can be determined with minimum deviation by utilizing the finite element analysis.
Keywords: Laser Metal Deposition (LMD), dual-beam process, wire-based Laser Metal Deposition (LMD-w), Finite Element Method (FEM)
Published in DKUM: 23.09.2021; Views: 1112; Downloads: 62
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