Journal articles: 'DMLS'

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Ranjan Pradhan, Smruti, Rupinder Singh, and Sukhwant Singh Banwait. "Comparison of DMLS and DMLS-waste assisted investment casting." Materials Letters 324 (October 2022): 132782. http://dx.doi.org/10.1016/j.matlet.2022.132782.

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Mangano, Francesco, Carlo Mangano, Adriano Piattelli, and Giovanna Iezzi. "Histological Evidence of the Osseointegration of Fractured Direct Metal Laser Sintering Implants Retrieved after 5 Years of Function." BioMed Research International 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/9732136.

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Background. Direct metal laser sintering (DMLS) is an additive manufacturing technique that allows the fabrication of dental implants layer by layer through the laser fusion of titanium microparticles. The surface of DMLS implants is characterized by a high open porosity with interconnected pores of different sizes; therefore, it has the potential to enhance and accelerate bone healing. To date, however, there are no histologic/histomorphometric studies in the literature evaluating the interface between bone and DMLS implants in the long-term. Purpose. To evaluate the interface between bone and DMLS implants retrieved after 5 years of functional loading. Methods. Two fractured DMLS implants were retrieved from the human jaws, using a 5 mm trephine bur. Both the implants were clinically stable and functioned regularly before fracture. The specimens were processed for histologic/histomorphometric evaluation; the bone-to-implant contact (BIC%) was calculated. Results. Compact, mature lamellar bone was found over most of the DMLS implants in close contact with the implant surface; the histomorphometric evaluation showed a mean BIC% of 66.1% (±4.5%). Conclusions. The present histologic/histomorphometric study showed that DMLS implants were well integrated in bone, after 5 years of loading, with the peri-implant bone undergoing continuous remodeling at the interface.

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Krishnan, Manickavasagam, Eleonora Atzeni, Riccardo Canali, Flaviana Calignano, Diego Manfredi, Elisa Paola Ambrosio, and Luca Iuliano. "On the effect of process parameters on properties of AlSi10Mg parts produced by DMLS." Rapid Prototyping Journal 20, no. 6 (October 20, 2014): 449–58. http://dx.doi.org/10.1108/rpj-03-2013-0028.

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Purpose – The aim of this research is to reach a deep understanding on the effect of the process parameters of Direct Metal Laser Sintering process (DMLS) on macroscopic properties (hardness and density) of AlSi10Mg parts and resulting microstructure. Design/methodology/approach – A full factorial design of experiment (DOE) was applied to determine the most significant process parameter influencing macroscopic properties of AlSi10Mg parts manufactured by DMLS process. The analysis aims to define the optimum process parameters and deduce the process window that provides better macroscopic properties of AlSi10Mg parts. Optical microscopy observations are carried out to link the microstructure to macroscopic properties. Findings – Macroscopic properties of DMLS parts are influenced by the change in process parameters. There is a close correlation between the geometry of scan tracks and macroscopic properties of AlSi10Mg parts manufactured by DMLS process. Originality/value – The knowledge of utilizing optimized process parameters is important to fabricate DMLS parts with better mechanical properties. The present research based on applying experimental design is the first analysis for AlSi10Mg parts produced in DMLS process.

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Śliwa, Romana Ewa, Jacek Bernaczek, and Grzegorz Budzik. "The Application of Direct Metal Laser Sintering (DMLS) of Titanium Alloy Powder in Fabricating Components of Aircraft Structures." Key Engineering Materials 687 (April 2016): 199–205. http://dx.doi.org/10.4028/www.scientific.net/kem.687.199.

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This study presents detailed characteristics of the DMLS method as used for titanium alloy powder with reference to a possible intended use in aeronautics applications.In the present study test models were made, designed for trials in which the model material properties are to be determined and which specify the basic features of the RP/DMLS technique. In order to evaluate the ultimate use of the DMLS technique in fabricating titanium alloy parts, the following procedures were conducted: tensile and upsetting tests for Ti6Al4V alloy samples (a comparative analysis for DMLS models and models fabricated, respectively, from titanium sheet and bar was carried out), an SEM analysis of the microstructure of the fragments of the surface of polished and etched samples, a Vickers hardness test and an analysis of the accuracy of the reproduction of the shape and roughness of the model fabricated in the DMLS procedure. A detailed analysis of the DMLS method significantly supplements the existing body of knowledge on innovative rapid prototyping techniques [1–4], and the results allow us to specify a group of aircraft structure components which may be fabricated using this method. Excellent strength properties of DMLS models and the possibility of improving surface quality by mechanical working enable the fabrication of advanced aircraft structure components operated in target conditions (under load).

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Konečná, Radomila, Ludvík Kunz, Pavel Pokorný, and Gianni Nicoletto. "Fatigue Crack Growth and Threshold Behavior of DMLS Ti6Al4V." Solid State Phenomena 267 (October 2017): 157–61. http://dx.doi.org/10.4028/www.scientific.net/ssp.267.157.

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Growth of long fatigue cracks in Ti6Al4V alloy manufactured by direct metal laser sintering (DMLS) was investigated. Two DMLS systems, EOSINT M270 and EOSINT M290, with different process parameters were used for production of CT specimens having three different orientations of crack propagation with respect to the DMLS build direction. The as-built specimens were stress relieved at 740 °C. The fatigue crack growth curve and the threshold values of the stress intensity factor for crack propagation were experimentally determined. It has been found that the chosen DMLS processing parameters and the used stress relieving procedure results in material exhibiting isotropic crack growth behavior, i.e. the crack growth was found to be independent of the DMLS build direction. The fatigue crack growth rates and the threshold values for the crack growth were compared with published results characterizing the as-built material and material after different post processing heat treatments.

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Walker, S. B. "The Defence Medical Library Service and Military Medicine." Journal of The Royal Naval Medical Service 91, no. 3 (December 2005): 170–76. http://dx.doi.org/10.1136/jrnms-91-170.

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AbstractThe Defence Medical Library Service (DMLS) supports the clinical practice and career development of military health professionals across the world. Clinical governance and the need for medical knowledge to be evidence-based means the DMLS has a central role to play in support of defence medicine. The DMLS is important for enabling health professionals to make sense of the evidence-based pyramid and the hierarchy of medical knowledge. The Royal Centre for Defence Medicine (RCDM) in Birmingham is recognised as an international centre of excellence. The information, knowledge and research requirements of the RCDM will provide opportunities for the DMLS to support and engage with the academic community.

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Raj, B. Anush, J. T. Winowlin Jappes, M. Adam Khan, V. Dillibabu, and N. Rajesh Jesudoss Hynes. "Studies on Mechanical Attrition and Surface Analysis on Heat-Treated Nickel Alloy Developed through Additive Manufacturing." Advances in Materials Science and Engineering 2022 (April 9, 2022): 1–8. http://dx.doi.org/10.1155/2022/4861346.

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In this paper, the nickel-based superalloy SU718 is developed through the Direct Metal Laser Sintering (DMLS), an additive manufacturing process. Further, the material has been focused to study the effect of heat treatment and abrasive particle erosion. Two different heat treatment (HT) cycles are planed with ageing and annealing to enrich the metallurgical quality of the DMLS processed SU718 alloy. The heat treatment is performed with two different combinations of temperatures for annealing/solutionizing followed by ageing to improve the metallurgical properties. The influence of heat treatment on additively manufactured IN718 is imparting variations in the hardness, microstructure, and erosion resistance. Vickers hardness for as built, HT 1, and HT 2 of DMLS alloy is 264.15, 385.55, and 352.43 Hv; which has been increased for 45% for HT 1 and 33% for HT 2 from the as built DMLS alloy. After solutionizing, the grains are refined within the track boundary and the majority of the grains are homogenized. The air jet erosion test arrangement is used to conduct the study at a velocity of 250 m/s and impact angle of 90° at room temperature. The hardness of the treated samples has taken vital role to resist the erosion. The rate of erosion is higher for bare DMLS alloy whereas HT 1 has low erosion rate when compared with HT 2 and bare DMLS alloy. The erosion morphology of the samples was carried out by SEM images, and erosion mechanism is discussed. The ploughing and microcutting were found in all the impact angles, whereas erodent impingement is found in the bare DMLS alloy in additional. The good erosion resistance is observed for HT 1 DMLS alloy in all the impact angles.

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Nicoletto, Gianni, Radomila Konečná, Ludvík Kunz, and Martin Frkáň. "Influence of as-built surface on fatigue strength and notch sensitivity of Ti6Al4V alloy produced by DMLS." MATEC Web of Conferences 165 (2018): 02002. http://dx.doi.org/10.1051/matecconf/201816502002.

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Direct Metal Laser Sintering (DMLS) is one of the additive manufacturing technologies involving a metal powder bed and a laser source to obtain components of complex geometry. The fatigue life of an as-built DMLS part is negatively influenced by the rough surface compared to a machined surface. Since most DMLS components are expected to have also stress concentrations, here the combined effect on fatigue of a as-built surface and a geometrical notch in as-built DMLS Ti6Al4V was investigated using a new test methodology. Miniature specimens having three different directions with respect to build direction were fabricated and tested determining the directional fatigue notch sensitivity of as-built DMLS Ti6Al4V Optical inspection of notch surface quality and roughness measurements demonstrated a ranking of the directional notches that inversely correlated to the measured fatigue performance. The link among the curved surface orientation, the peculiar layer-wise additive manufacturing fabrication and the fatigue notch sensitivity is clarified.

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Mangano, F., L. Chambrone, R. van Noort, C. Miller, P. Hatton, and C. Mangano. "Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature." International Journal of Biomaterials 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/461534.

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Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices.Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties.Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, andin vitrocell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used.Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality.Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed.

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Mangano, Carlo, Francesco Mangano, Jamil Shibli, Leandro Roth, Gianmaria d’ Addazio, Adriano Piattelli, and Giovanna Iezzi. "Immunohistochemical Evaluation of Peri-Implant Soft Tissues around Machined and Direct Metal Laser Sintered (DMLS) Healing Abutments in Humans." International Journal of Environmental Research and Public Health 15, no. 8 (July 30, 2018): 1611. http://dx.doi.org/10.3390/ijerph15081611.

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Background: Direct metal laser Sintering (DMLS) is an additive manufacturing technique that allows fabrication of dental implants and related components with a highly porous surface. To date, no human studies have investigated the soft tissue adhesion and presence of inflammatory infiltrate with porous DMLS healing abutments (HAs), nor have they compared these with the classic machined ones. Purpose: To evaluate the degree of cell adhesion (integrin expression) and the quantity/quality of inflammatory infiltrate, on HAs with different surfaces; full DMLS, full machined, and hybrid (half DMLS and half machined). Methods: Fifty implant patients were randomly assigned to receive one of these different Has: T1, full DMLS (11 subjects); T2, machined in the upper portion and DMLS in the lower one (10 subjects); T3, DMLS in the upper portion and machined in the lower one (19 subjects); T4, full machined (10 patients). Thirty days after placement, circular sections of soft tissues around HAs were retrieved for immunohistochemical evaluation. Results: With regard to the adhesion molecules, the samples showed different intensity of integrin expression, with a statistically significant difference (p < 0.001) between T1 and the other groups. All the samples were positive for the different clusters related to the inflammatory infiltrate (T lymphocytes, CD3; B lymphocytes, CD20; and macrophages, CD68), but a lower infiltrate was found in T1, with statistically significant differences (p < 0.001) among the groups. Conclusions: The HA surface seems to influence the degree of cell adhesion and the inflammatory infiltrate of the surrounding soft tissues.

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Żaba, Krzysztof, Lechosław Tuz, Piotr Noga, Stanislav Rusz, and Rostislav Zabystrzan. "Effect of Multi-Variant Thermal Treatment on Microstructure Evolution and Mechanical Properties of AlSi10Mg Processed by Direct Metal Laser Sintering and Casting." Materials 15, no. 3 (January 27, 2022): 974. http://dx.doi.org/10.3390/ma15030974.

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This article presents a study on the influence of temperature and time of multi-variant heat treatment on the structure and properties of materials produced in direct metal laser sintering (DMLS) and casting technology. The materials were manufactured in the form of cuboidal elements with a cross-section of 1.5 mm × 15 mm and a length of 60 mm. The samples prepared in this way had a similar volume, but due to the production technology the metal crystallization took place at different rates and directions. In the cast, the direction of heat transfer was toward the mold, and the DMLS was directed locally layer by layer. The small thickness of the cast material allowed reaching conditions similar to the DMLS cooling process. Both DMLS and cast samples show similar mechanical properties (hardness) achieved after long ageing time, i.e., 16 h at 170 °C. The maximum hardness was observed for 8 h. In the DMLS samples, in contrast to cast samples, no lamellar precipitates of silicon were observed, which indicates their better resistance to cracking

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Sitek, Ryszard, Krzysztof Kulikowski, Krystian Paradowski, Kamil Gancarczyk, Monika Losertová, Akira Kobayashi, Joanna Moneta, and Janusz Kamiński. "Influence of Ion Nitriding on Microstructure and Properties of Haynes 282 Nickel Superalloy Specimens Produced Using DMLS Technique." Materials 16, no. 14 (July 15, 2023): 5020. http://dx.doi.org/10.3390/ma16145020.

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The paper investigates the influence of the ion-nitriding process on the microstructure, corrosion resistance, and tensile strength at elevated temperatures of Haynes 282 nickel superalloy specimens produced by the Direct Metal Laser Sintering (DMLS) technique. The study was performed for two conditions, i.e., as-built by DMLS method and as-built by DMLS method + covered by a layer containing CrN + Cr2N phases. An analysis of the surface morphology revealed that the ion-nitriding process significantly affects the physical and chemical phenomena occurring on the specimen’s surface. The XRD measurement of the specimens showed that preparing them with the DMLS method as well as following a nitriding process produced residual tensile stresses. Based on the measurement of the nanohardness distribution through the layer approximatively of 7 μm in width and the superalloys substrate, the results of the nanohardness showed the maximum values of 27 GPa and 13.5 GPa for the nitrided layer and the substrate, respectively. The surface protection from the nitrided layer proved a positive effect on the corrosion resistance of the DMLS specimens in the solution of 0.1 M Na2SO4 + 0.1 M NaCl at room temperature. The results of the tensile tests at 750 °C showed that the ion-nitriding process did not significantly affect the elevated-temperature tensile strength of the superalloy specimens produced with the DMLS technique.

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Ai, R., D. Boyle, D. Hammaker, K. Deane, V. M. Holers, A. Matti, W. Robinson, et al. "OP0337 DIFFERENTIAL METHYLATION OF PERIPHERAL BLOOD ADAPTIVE IMMUNE CELLS IN INDIVIDUALS AT HIGH RISK FOR RA AND WITH EARLY RA COMPARED WITH CONTROLS IDENTIFIES PATHWAYS IMPORTANT IN TRANSITION TO ARTHRITIS." Annals of the Rheumatic Diseases 79, Suppl 1 (June 2020): 207.2–207. http://dx.doi.org/10.1136/annrheumdis-2020-eular.2989.

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Background:The “Targeting Immune Responses for Prevention of RA” (TIP-RA) collaboration studies individuals at high risk for developing RA because of serum anti-citrullinated protein antibody positivity in absence of arthritis, and is focused on defining how they transition from at-risk to classifiable disease. One potential mechanism is through alterations in epigenetics patterns in adaptive immune cells.Objectives:Previous studies showed that DNA methylation patterns of early RA (ERA) synoviocytes differ from long-standing RA, suggesting that abnormal methylation occurs early in synovium and evolves over time. To extend these observations, we performed a cross-sectional analysis in TIP-RA of DNA methylation signatures in peripheral blood cells in ERA, at-risk anti-CCP3+ individuals and demographically matched CCP- controls.Methods:Genomic DNA was isolated from two independent cohorts of CCP- (cohorts 1 and 2, respectively: B cell: n = 17/34; memory T cell: n = 21/34; and naïve T cell: n = 21/33), CCP3+ (B cell: n = 18/37; memory T cell: n = 20/36; and naïve T cell: n = 20/35), and CCP3+ ERA (B cell: n = 4/18; memory T cell: n = 5/18; and naïve T cell: n = 5/18) after separating PBMCs using antibodies and magnetic beads. Methylation was measured by Illumina Infinium MethylationEPIC chip. Differentially methylated loci (DMLs) were identified using Welch’s t-test and mapped to gene promoter regions to define DM genes (DMGs). Principal component analysis (PCA) was used to represent relationship among groups. Pathway analysis was applied by Reactome.Results:For the initial cohort, 1494, 1097 and 1330 DMLs were identified among CCP+, CCP- and ERA in B cells, memory T cells and naïve T cells, respectively. For the confirmatory cohort, 523, 793 and 548 DMLs were found in corresponding cell populations. The DML overlap between the 2 cohorts was highly significant (p= 2.48E-77). The DMLs were combined for both groups and corresponded to 411, 412, and 351 DMGs in B cells, memory T cells and naïve T cells. Of these, we found 246, 198 and 195 DMGs between CCP3+ and ERA in each peripheral blood cell population, respectively. PCA showed separation of CCP+, CCP- and ERA in each of the three blood cell types by DMLs (Fig. 1). DMGs were mapped to biological pathways to identify DM pathways. Although most were not significant, there were several highly significant differences comparing CCP+, ERA and CCP- in memory T cells involving pathways, including “Interferon gamma signaling” (FDR 7.48E-14), “PD-1 signaling” (FDR 8.71E-10), “Translocation of ZAP-70 to Immunological synapse” (FDR 4.75E-10), and “Phosphorylation of CD3 and TCR zeta chains” (FDR 8.71E-10).Figure 1.PCA shows the separation of CCP+, CCP- and ERA patients in memory T cells in confirmatory cohort.Conclusion:We identified reproducible methylation signatures of CCP-, CCP+, and ERA in peripheral blood B cells, memory T cells and naïve T cells in initial and confirmatory cohorts. The methylome of ERA also demonstrated a distinctive pattern from CCP+, indicating that progression to RA is accompanied by epigenetic remodeling, especially in T cell signaling and interferon responses. These signatures identify critical pathways in CCP positivity and classifiable RA and could provide the basis of novel interventions to prevent disease.Disclosure of Interests:Rizi Ai: None declared, David Boyle: None declared, Deepa Hammaker: None declared, Kevin Deane Grant/research support from: Janssen, Consultant of: Inova, ThermoFisher, Janseen, BMS and Microdrop, V. Michael Holers Grant/research support from: Janssen, Celgene, and BMS, Andre Matti: None declared, William Robinson: None declared, Jane Buckner Grant/research support from: Bristol-Myers Squibb, Janssen, Navin Rao Shareholder of: Janssen Pharmaceuticals, Employee of: Janssen Pharmaceuticals, Frederic Baribaud Shareholder of: Janssen Research & Development, LLC, Employee of: Janssen Research & Development, LLC, Alyssa Johnsen Employee of: Janssen, Sunil Nagpal Shareholder of: Janssen Pharmaceuticals, Employee of: Janssen Pharmaceuticals, Wei Wang: None declared, Gary Firestein Grant/research support from: Lilly, Janssen, Abbvie

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Lapcevic, Ana R., Danimir P. Jevremovic, Tatjana M. Puskar, Robert J. Williams, and Dominic Eggbeer. "Comparative analysis of structure and hardness of cast and direct metal laser sintering produced Co-Cr alloys used for dental devices." Rapid Prototyping Journal 22, no. 1 (January 18, 2016): 144–51. http://dx.doi.org/10.1108/rpj-04-2014-0051.

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Purpose – The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM samples) and additive direct metal laser sintering technology (DMLS samples), and to compare the results. Design/methodology/approach – CCM samples were made in a conventional casting machine, using remanium 800+ Co-Cr dental alloy (Dentaurum, Ispringen, Germany). DMLS samples were fabricated out of EOS CC SP2 Co-Cr alloy (EOS, GmbH, Munich, Germany) using DMLS technology. Samples for structural analysis were plate-shaped (10 × 10 × 1.5 mm3) and for the hardness test were prismatic-shaped (55 × 10.2 × 11.2 mm3). Structure was analysed via an inverting microscope and colour metallography method. Findings – CCM samples have a dense, irregular dendritic mesh, which is typical for the metallic phase of the Co-Cr dental alloy. DMLS alloy has a more homogenous and more compact structure, compared to CCM. Metals, the alloy basis consists of, form semilunar stratified layers, which are characteristic for the additive manufacturing (AM) technique. Hardness values of DMLS (mean value was 439.84 HV10) were found to be higher than those of CCM (mean value was 373.76 HV10). Originality/value – There are several reports about possible use of AM technologies for manufacturing dental devices, and investigation of mechanical properties and biocompatibility behaviour of AM-produced dental alloys. Microstructure of Co-Cr alloy made with DMLS technology has been introduced for the first time in the present paper.

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BOJKO, Łukasz, Wojciech RYNIEWICZ, Anna M. RYNIEWICZ, and Marcin KOT. "STUDY OF THE IMPACT OF INCREMENTAL TECHNOLOGY ON MECHANICAL AND TRIBOLOGICAL PROPERTIES OF BIOMATERIALS." Tribologia 273, no. 3 (June 30, 2018): 29–38. http://dx.doi.org/10.5604/01.3001.0010.6117.

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The latest method for creating denture replenishment in CAD / CAM systems is Direct Metal Laser Sintering (DMLS) technology. With the use of DMLS, prosthodontics, implant prosthetics, and facial-cranialjaw surgery adapted to individual patient conditions can be realized. The aim is to evaluate the strength, microstructure, and tribological properties of Ti6Al4V and CoCrMo alloys obtained from DMLS technology in the aspect of therapeutic constructions. The conducted tests show that, in the DMLS technology, as compared to milling technology preceded by casting and forging or pressed powder and sintering, for the same percentage composition of elements, the micromechanical properties, microstructural and tribological change. This procedure, from which constructions for various dental applications are obtained, is the new technology preferred for making permanent restorations faced with ceramics, producing intravascular implants, and implants of the temporomandibular joint. It can be an alternative to conventional cast-based methods and CAD / CAM based milling.

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Karolewska, Karolina, and Bogdan Ligaj. "Mechanical properties comparison of Ti6Al4V produced by different technologies under static load conditions." MATEC Web of Conferences 290 (2019): 08010. http://dx.doi.org/10.1051/matecconf/201929008010.

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The most commonly used technology among the additive manufacturing is Direct Metal Laser Sintering (DMLS). This process is based on selective laser sintering (SLS). The method gained its popularity due to the possibility of producing metal parts of any geometry, which would be difficult or impossible to obtain by the use of conventional manufacturing techniques. Materials used in the elements manufacturing process are: titanium alloys (e.g. Ti6Al4V), aluminium alloy AlSi10Mg, etc. Elements printed from Ti6Al4V titanium alloy find their application in many industries. Details produced by additive technology are often used in medicine as skeletal, and dental implants. Another example of the DMLS elements use is the aerospace industry. In this area, the additive manufacturing technology produces, i.a. parts of turbines. In addition to the aerospace and medical industries, DMLS technology is also used in motorsport for exhaust pipes or the gearbox parts. The research objects are samples for static tests. These samples were made of Ti6Al4V alloy by the DMLS method and the rolling method from a drawn rod. The aim of the paper is the mechanical properties comparative analysis of the Ti6Al4V alloy produced by the DMLS method under static loading conditions and microstructure analysis of this material.

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Sitek, Ryszard, Sandra Puchlerska, Ilona Nejman, Kamil Majchrowicz, Zbigniew Pakieła, Krzysztof Żaba, and Jarosław Mizera. "The Impact of Plastic Deformation on the Microstructure and Tensile Strength of Haynes 282 Nickel Superalloy Produced by DMLS and Casting." Materials 15, no. 21 (October 27, 2022): 7545. http://dx.doi.org/10.3390/ma15217545.

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The article presents the results of research on the influence of plastic deformation on the microstructure and tensile strength of Haynes 282 nickel superalloy produced by direct metal laser sintering (DMLS) and a conventional technique (casting). Samples were tested for dimensional accuracy using a 3D scanner. Then, the samples were subjected to plastic deformation by rolling. The microstructures of the DMLS and the as-cast samples were analysed using a scanning electron microscope. The strength properties of the samples were determined in a static tensile test. Microhardness measurements of the samples were also performed. Based on the analysis of the dimensional accuracy, it was found that the surface quality of the components produced by DMLS is dependent on the input parameters of the 3D printing process. Using the DMLS method, it is possible to produce Haynes 282 with a fine-crystalline microstructure containing dendrites. The fine-crystalline dendritic microstructure and low porosity showed very good tensile strength compared to the as-cast material. It was also found that the increase in the degree of plastic deformation of the as-cast Haynes 282 and the samples produced by the DMLS technique resulted in an increase in the strength of the tested samples, with reduced ductility.

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Ciftci, Jakub, Ryszard Sitek, and Jarosław Mizera. "Analysis of direct metal laser sintering ‒ DMLS and heat treatment influence on the Inconel 713C nickel alloy structure." Welding Technology Review 93, no. 3 (August 6, 2021): 49–56. http://dx.doi.org/10.26628/wtr.v93i3.1142.

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The group of nickel based superalloys produced in the DMLS (Direct Metal Laser Sintering) process is limited to materials, which produced conventionally do not have properties to allow to use them for rotating components of aircraft engines. This work attempts to optimize the technological parameters of the DMLS process for the Inconel 713C nickel superalloy. A heat treatment was performed for selected samples to investigate the effect on the morphology of the Ni3Al phase. The microstructure analysis and hardness tests were carried out. The material after the DMLS process was characterized by the presence of much smaller dendrites than the cast material and exceeded its hardness. For the tested variants of heat treatment, the material was characterized by smaller sizes of the Ni3Al phase. In order to ensure the stability of the microstructure, an optimization of the dedicated heat treatment after the DMLS process is required, as the standard heat treatment for Inconel 713C cast nickel superalloy does not fully recrystallize the material.

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Sharma, Monica, Ajay Bansal, Sunny Panthi, Shefali Malik, and Atulya Sharma. "To Evaluate the Marginal Fit of Metal Copings Fabricated by Conventional Casting Procedure and Direct Metal Laser Sintering Technology – an In Vitro Study." Dental Journal of Advance Studies 05, no. 01 (April 2017): 039–46. http://dx.doi.org/10.1055/s-0038-1672079.

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Abstract Purpose: The purpose of this in vitro study was to evaluate marginal fit of cobalt- chromium (Co-Cr) copings fabricated by direct metal laser sintering system (DMLS) and conventional lost-wax technique (LW). Materials and method: Forty tooth preparations were carried out over extracted mandibular molars. They were divided into two groups A and B of 20 each. For group A Co-Cr copings were fabricated by direct metal laser sintering (DMLS) and for group B by lost wax technique (LW). Glass –ionomer cement (GIC) was used to tack the copings over their preparations. Marginal fit was then evaluated directly under the stereomicroscope. Results: The mean marginal gap of group A was 27.9 ± 2.4 μm and group B was 40.4 ±6 μm. Statistical analysis using t - test showed highly significant difference (P>.05) between the marginal mean of the DMLS (group A) compared to LW (group B). Conclusion: The DMLS copings demonstrated superior marginal fit compared to that of conventional Co-Cr casted copings.

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Crowe, Kathryn, and Mark Guiberson. "Professionals’ Perspectives on Supporting Deaf Multilingual Learners and Their Families." Journal of Deaf Studies and Deaf Education 26, no. 1 (August 26, 2020): 70–84. http://dx.doi.org/10.1093/deafed/enaa025.

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Abstract Parents frequently report that advice from professionals is important in making decisions about how their child with hearing loss will communicate. Little is currently known about how professionals support parents raising children with hearing loss in spoken language multilingual environments, children who are described as d/Deaf multilingual learners (DMLs). The purpose of this phenomenological study was to gain insight into professionals’ perspectives and experiences working with such families, particularly in relation to supporting parents in decision-making about multilingualism and language choice. Nineteen professionals discussed their experiences working with DMLs and their families, the role of professionals in decision-making about multilingualism and language choice, and the factors that they considered were important when supporting DMLs and their families. Inductive thematic analysis yielded three themes: child characteristics (language, development), negotiating and supporting language (information, parents’ language, role of language, timing, leadership, language management), and professional issues (knowledge, resources). This paper provides an important insight into professional considerations in supporting DMLs and their families, such as the role and functioning of evidence-based practice.

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Wirwicki, Mateusz. "Effect of the aging process at a temperature of 300 degrees Celsius of Ti6Al4V alloy on mechanical strength under static loading conditions." MATEC Web of Conferences 290 (2019): 08017. http://dx.doi.org/10.1051/matecconf/201929008017.

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Conventional construction of components is slowly being replaced by rapid prototyping and the use of DMLS technology. The development of DMLS requires conducting experimental studies that build a knowledge base that allows for the averaging of mechanical properties. verification of how the initiation of the crack occurs in the material and how the energy is propagated in the samples that were made by a conventional method compared to the samples, where the method of sintering titanium layers will be used. The literature analysis showed no research results relating to the impact of values of strength parameters on the structure of materials produced by the DMLS method. Titanium samples made with the additive method and the conventional titanium grade 5 Ti6Al4V titanium method, which is used, among others, in medicine, were used for the tests. The article presents the influence of material structure on mechanical properties (Re, Rm, A, Z). The presented research is preliminary research defining the properties of the material, which are gaining more and more application by using the DMLS method in the construction of machines and in medicine.

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Băilă, Diana Irinel. "Experimental Researches of Co-Cr Alloys Powders Manufactured by Sintering Process DMLS and Ni-Cr Alloys Used in Dentistry." Advanced Materials Research 1119 (July 2015): 433–37. http://dx.doi.org/10.4028/www.scientific.net/amr.1119.433.

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The purpose of this study was to evaluate the chemical and metallurgical aspects, mechanical properties and hardness of the Co-Cr alloy powders manufactured by sintering process DMLS and compared with Ni-Cr alloys used for personalized dental crowns.In dentistry are develop new methods to obtain personalized dental crowns quickly, the cost is not expensive and is identically with the dental scan realized by dentist. DMLS sintering manufacturing is a new method who permits to realize in the same day the dental crowns with the first control.Powders of Co-Cr alloys presents good sintered properties, good mechanical properties and the sintered probes don’t present tensile strength in the material after DMLS process.

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Bača, Adrián, Radomila Konečná, and Gianni Nicoletto. "Influence of the Direct Metal Laser Sintering Process on the Fatigue Behavior of the Ti6Al4V Alloy." Materials Science Forum 891 (March 2017): 317–21. http://dx.doi.org/10.4028/www.scientific.net/msf.891.317.

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Direct Metal Laser Sintering (DMLS) is additive manufacturing (AM) process that can produce near net shape parts from metal powders such as titanium alloys. DMLS is a layer by layer additive manufacturing technique based on high power fiber laser that creates solid layers from loose powder material and joins them in an additive manner. The specific DMLS process conditions, lead to a specific and complex microstructure and to mechanical properties that show a degree of directionality. It was found that microstructural characteristics are related to the building process parameters. The aim of this work is to evaluate the fatigue performance of the Ti6Al4V alloy depending on the process parameters, building orientations and post-process heat treatment.

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Diamantopoulos, Nikolaos-Panteleimon (Pandelis), Suguru Yamaoka, Takuro Fujii, Hidetaka Nishi, Koji Takeda, Tai Tsuchizawa, Takaaki Kakitsuka, and Shinji Matsuo. "47.5 GHz Membrane-III-V-on-Si Directly Modulated Laser for Sub-pJ/bit 100-Gbps Transmission." Photonics 8, no. 2 (January 27, 2021): 31. http://dx.doi.org/10.3390/photonics8020031.

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Near-future upgrades of intra data center networks and high-performance computing systems would require optical interconnects capable of operating at beyond 100 Gbps/lane. In order for this evolution to be achieved in a sustainable way, high-speed yet energy-efficient transceivers are in need. Towards this direction we have previously demonstrated directly-modulated lasers (DMLs) capable of operating at 50 Gbps/lane with sub-pJ/bit efficiencies based on our novel membrane-III-V-on-Si technology. However, there exists an inherent tradeoff between modulation speed and power consumption due to the carrier-photon dynamics in DMLs. In this work, we alleviate this tradeoff by introducing photon–photon resonance dynamics in our energy-efficient membrane DMLs-on-Si design and demonstrate a device with a maximum 3-dB bandwidth of 47.5 GHz. This denotes a bandwidth increase of more than 2x times compared to our previous membrane DMLs-on-Si. Moreover, the DML is capable of delivering 60-GBaud PAM-4 signals under Ethernet’s KP4-FEC threshold (net data rate of 113.42 Gbps) over 2-km of standard single-mode fiber transmission. DC energy-efficiencies of 0.17 pJ/bit at 25 °C and 0.34 pJ/bit at 50 °C have been achieved for the > 100-Gbps signals. Deploying such DMLs in an integrated multichannel transceiver should ensure a smooth evolution towards Terabit-class Ethernet links and on-board optics subsystems.

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Ashwath, P., M. Anthony Xavior, P. Jeyapandiarajan, J. Joel, and Andre Batako. "Surface Finish and Property Evaluation of Direct Metal Laser Sintered (DMLS) Al-Si-10Mg alloy." Journal of Physics: Conference Series 2198, no. 1 (May 1, 2022): 012055. http://dx.doi.org/10.1088/1742-6596/2198/1/012055.

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Abstract Recently, Additive Manufacturing (AM) technique is widely recognized by engineering sectors for its novel capability to manufacture components directly from a Computer-Aided Model (CAM). Direct Metal Laser Sintering (DMLS) is an upcoming modernization among different AM techniques. DMLS is one of the AM techniques attuned to produce the three-dimensional components or expensive component by layer-by-layer powder deposition and laser sintering avoiding utilization of any alternative additional processes. Current research work focus on fabricating an Al-Si-10Mg aluminium alloy by DMLS process which is studied for the influence of specimen geometry, surface finish and build orientation on the mechanical strength. The importance of the sample studied for the geometry and surface finish is quite necessary specifically for dynamic applications.

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Konečná, Radomila, Gianni Nicoletto, Adrián Bača, and Ludvík Kunz. "Metallographic Characterization and Fatigue Damage Initiation in Ti6Al4V Alloy Produced by Direct Metal Laser Sintering." Materials Science Forum 891 (March 2017): 311–16. http://dx.doi.org/10.4028/www.scientific.net/msf.891.311.

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Direct Metal Laser Sintering (DMLS) is a complex process where a part is build-up by localized melting of gas atomized powder layers by a concentrated laser beam followed rapid solidification. The microstructure of DMLS produced material is substantially different from that of conventionally manufactured materials, although the ultimate strength is similar. However, yield strength and elongation and especially fatigue behavior may vary considerably according to the process parameters and post fabrication heat treatment because they affect structural heterogeneity, porosity content, residual stresses, and surface conditions. Fatigue tests of DMLS Ti6Al4V alloy are interpreted in the light of a thorough metallographic and fractographic investigation. The fatigue crack initiation for three different cyclic stress directions with respect to build direction is determined by fractography.

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Konečná, Radomila, Gianni Nicoletto, Adrián Bača, and Ludvík Kunz. "High Cycle Fatigue Life of Ti6Al4V Alloy Produced by Direct Metal Laser Sintering." Solid State Phenomena 258 (December 2016): 522–25. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.522.

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High cycle fatigue life of Ti6Al4V alloy specimens manufactured by Direct Metal Laser Sintering (DMLS) was experimentally determined. The DMLS fabrication process was characterized by a 400 W laser power and 50 μm layer melted thickness. Post-fabrication heat treatment consisted in stress relieving for 3 h at 720 °C in vacuum with subsequent cooling in argon atmosphere. Fatigue testing of specimens oriented in three different directions with respect to the material build direction was performed with the aim to examine the influence of the layered microstructure on the fatigue behavior. Results of measurement of surface roughness, metallographic examinations of the layered material and fractographic investigation of the fatigue fracture surfaces were employed in the discussion of fatigue crack initiation in DMLS fabricated Ti6Al4V alloy.

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Balaji, Bonothu, Dileep Nag Vinnakota, Vijaya Sankar V, and Srinivas Rao Pottem. "Thermal expansion and corrosion resistance of cobalt-chromium alloys fabricated by contemporary manufacturing processes. An in vitro study." Journal of Oral Research 11, no. 5 (October 30, 2022): 1–12. http://dx.doi.org/10.17126/joralres.2022.058.

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In Purpose: The fabrication technique can influence the mechanical properties of Cobalt-Chromium (Co-Cr) dental alloys. Hence, the present study aims to determine the corrosion resistance and thermal expansion of alloys manufactured using three contemporary techniques. Material and Methods: A total of nine specimens of Co-Cr alloy were prepared according to ISO 22674 by each one of the three manufacturing processes (three in each process); conventional casting, direct metal laser sintering (DMLS) and milling (MIL). All these specimens were tested for coefficient of thermal expansion and corrosion resistance. The data was tabulated and analyzed statistically. Results: The difference in the thermal expansion of alloys fabricated using three techniques was non-significant at almost all the temperatures from 50 ºC to 950 ºC (p>0.05), except 450 ºC and 600 °C. The polarization resistance of specimens manufactured using the conventional method was more compared to DMLS and MIL at pH 5 (Conventional>MIL>DMLS) (p<0.001). Conclusion: The thermal expansion behavior of alloys manufactured using the three selected techniques were similar, whereas, at acidic pH, the corrosion resistance of conventional and MIL were better than the DMLS.

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Yılmaz, Mustafa Safa, Gökhan Özer, Zafer Çağatay Öter, and Onur Ertuğrul. "Effects of hot isostatic pressing and heat treatments on structural and corrosion properties of direct metal laser sintered parts." Rapid Prototyping Journal 27, no. 5 (June 10, 2021): 1059–67. http://dx.doi.org/10.1108/rpj-10-2020-0245.

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Purpose This paper aims to investigate the effects of various heat treatments on microstructure, hardness, porosity and corrosion properties of the parts. Design/methodology/approach Hot isostatic pressing (HIP) process, various heat treatments and their combinations were applied to the AlSi10Mg parts produced by direct laser metal sintering (DMLS). Findings It has been found that the HIP process, which is a post-processing process, reduces the amount of porosity in DMLS-AlSi10Mg material, thus improves corrosion resistance significantly. Originality/value In this study, the HIP process and subsequent T6 heat treatments were applied to AlSi10Mg parts produced by the DMLS technique. The study aims to increase the corrosion resistance of AlSi10Mg parts by reducing porosity with the HIP process and by altering the microstructure with the T6 process.

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Naiju, C. D., K. Annamalai, P. K. Manoj, and K. M. Ayaz. "Investigation on the Effect of Process Parameters on Hardness of Components Produced by Direct Metal Laser Sintering (DMLS)." Advanced Materials Research 488-489 (March 2012): 1414–18. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.1414.

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Direct metal laser sintering (DMLS) is one of the methods in layer manufacturing technologies by which metal powder can be directly used to produce both prototype and production tools. The components manufactured by DMLS should have essential hardness for its application in the industry. This study was carried out to determine the optimum process parameters influencing the hardness of the components produced by DMLS. Sintering speed, hatch spacing, post contouring, infiltration and hatch type are the process parameters taken up for study. Statistical design of experiments using Taguchi’s orthogonal array was employed for this study. The experimental data obtained were analyzed using ANOVA. From the results, it is found that one of the process parameters; scan spacing affects the hardness of the parts produced by this technology to a significant extent.

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Kumpaty, Subha, Sheku Kamara, Brandon Tomlin, Jisun Yoo, Hephzibah Kumpaty, Daniel Anderson, M. Govindaraju, Nitin Kanoongo, and K. Balasubramanian. "Effect of Heat Treatment on Mechanical/Metallurgical Properties of Direct Metal Laser Sintered 17-4 Precipitate Hardened Stainless Steel." Advanced Materials Research 699 (May 2013): 795–801. http://dx.doi.org/10.4028/www.scientific.net/amr.699.795.

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Greatbatch Medical, specializing in orthopedic implants and instruments, is currently utilizing direct metal laser sintering (DMLS) technology to develop concept prototypes. Greatbatch uses EOS GP1 Stainless Steel which adheres to the American standard for 17-4 Precipitation Hardened SS. Following DMLS, Greatbatch heat treats its parts to obtain desirable mechanical properties. In this study, three different heat treatment methods were examined: heat treatment and stress relief (HT+SR), stress relief (SR), and solution aging and annealing (SAA). The Vickers Hardness Test and the Tensile Strength Test were used to assess the mechanical properties of each sample. The research also included grain structure analysis using a Scanning Electron Microscope and surface roughness studies via profilometer measurements. For example, the HT+SR sample yielded 456 HV (hardness), an ultimate tensile strength of 1319 MPa, an yield strength of 1120 MPa, and 6.36% elongation. It was found that compared to the untreated sample, HT+SR decreased the total elongation by 73% and SAA decreased total elongation by 17% and additionally decreased hardness by 17%. It was learnt that stress relieving the part after DMLS was the superior method of choice based on its resulting mechanical properties. It was found that the grain structure of the non-treated sample resembled a solution treated sample and the stress-relieved sample actually matched an age-hardened sample. The sample that was precipitation hardened was actually over-aged. Thus it was found that the DMLS process seemed to be acting as an aging process while simultaneously building the part. Further studies in examining specific effects of DMLS and how it impacts what order heat treatments should follow would be appropriate.

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Dolinsek, Slavko. "Direct Metal Laser Sintering Some Improvements of the Materials and Process." Materials Science Forum 539-543 (March 2007): 2681–86. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.2681.

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For a comprehensive understanding of the direct metal laser sintering (DMLS) process and for the successful introduction of this technology, some investigations related to the characteristics of the powders and the individual sintered layers were therefore performed. Also possibilities of hard coatings deposition for further improvements the wear and temperature resistance of tool inserts, and investigations particularly focused into the industrial applications of DMLS tooling inserts are presented.

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Márquez, C., J. D. López, L. Cabrera, L. González, and J. Botana. "Study of the influence of laser energy density on the surface roughness of Scalmalloy^® samples manufactured by DMLS technology." IOP Conference Series: Materials Science and Engineering 1193, no. 1 (October 1, 2021): 012036. http://dx.doi.org/10.1088/1757-899x/1193/1/012036.

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Abstract Direct Metal Laser Sintering (DMLS) is an additive metal manufacturing technology that allows complex parts to be built without the design constraints of conventional technologies. In addition, the possibility of reusing powder reduces raw material consumption and the amount of waste generated. However, one of the disadvantages of this technology is that, in most cases, it requires post-processing tasks that increase manufacturing costs and delivery times. Some of these additional tasks are aimed at reducing the surface roughness of the parts obtained, using technologies such as grinding, mechanical polishing, shot blasting or electropolishing. This work proposes to improve the surface quality of parts manufactured by DMLS by controlling the processing parameters. In this way, the costs associated with these post-processing tasks could be reduced. Specifically, it is proposed to study the effect of the laser energy density applied to the surface of the parts during the manufacturing process on their surface quality. To carry out this study, powders of the Al-Mg-Sc alloy known as Scalmalloy®, developed to manufacture parts by means of DMLS with application in the aeronautical sector, have been used. In this sector, surface quality is one of the factors limiting the implementation of DMLS technology for the manufacture of parts considered critical.

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Jin, Max, Haseung Chung, Patrick Kwon, and Adil Akkouch. "Effects of Different Titanium Surfaces Created by 3D Printing Methods, Particle Sizes, and Acid Etching on Protein Adsorption and Cell Adhesion, Proliferation, and Differentiation." Bioengineering 9, no. 10 (September 28, 2022): 514. http://dx.doi.org/10.3390/bioengineering9100514.

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The surfaces of 3D printed titanium prostheses have major impacts on the clinical performance of the prostheses. To investigate the surface effects of the products generated by 3D printed titanium on osseointegration, six surface types of titanium discs produced by the direct metal laser sintering (DMLS) and electron beam melting (EBM) methods, with two sizes of titanium particles and post-printing acid etching, were used to examine the surface topography and to explore the protein adsorption, pro-inflammatory cytokine gene expressions, and MC3T3-E1 cell adhesion, proliferation, and differentiation. The EBM-printed disc showed a stripy and smooth surface without evidence of the particles used, while the DMLS surface contained many particles. After acid etching, small particles on the DMLS surface were removed, whereas the large particles were left. Moreover, distinct proteins with low molecular weights were attached to the 3D printed titanium discs but not to the pre-printing titanium particles. The small titanium particles stimulated the highest TNF-α and IL-6 gene expressions at 24 h. The alizarin red content and osteocalcin gene expression at day 21 were the highest in the groups of acid-etched discs printed by DMLS with the small particles and by EBM. Therefore, the acid-treated surfaces without particles favor osteogenic differentiation. The surface design of 3D printed titanium prostheses should be based on their clinical applications.

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Azevedo-Silva, Lucas José de, Brunna Mota Ferrairo, Renato José Berro-Filho, Fernanda Ferruzzi Lima, and José Henrique Rubo. "Lost-wax or laser sintering? Findings on marginal and internal adaptation of metallic copings." Research, Society and Development 10, no. 17 (December 22, 2021): e162101724429. http://dx.doi.org/10.33448/rsd-v10i17.24429.

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Marginal and internal adaptation are parameters of crucial importance to the success of prosthetic crowns. Automatized process creates an expectative of superior or equivalent results compared to restorations manufactured by conventional lost-wax technique. The purpose of this study was to evaluate the marginal adaptation and internal adaptation (cement space) of metal-ceramic crown copings produced by lost-wax (LW) and direct metal laser sintering (DMLS) techniques. An artificial lower first molar was prepared for a full crown, duplicated in plaster and scanned. Twenty metal-ceramic crown copings were fabricated in cobalt-chromium by the two techniques (n=10). The copings were filled with low viscosity silicone and seated on the prepared tooth, resulting in a replica of the internal space. The pellicle formed was embedded in heavy body silicone, sectioned and captured by means of a stereomicroscope at 50x magnification, according to replica technique (RT). Shapiro-Wilk test followed by Holm-Sidak test were used for statistical analysis (α=.05). Marginal adaptation presented no difference between LW (101.5 ± 41.6) and DMLS (86.3 ± 39.9) groups (p=0.24). Conventional LW technique showed significantly lower occlusal (p<0.008) and axial spaces (p<0.03). Measurements of all regions showed numerically larger adaptation values than that defined during design for DMLS group. Both the LW technique and the DMLS technique are within the clinically acceptable.

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Muiruri, Amos, Maina Maringa, and Willie du Preez. "Evaluation of Dislocation Densities in Various Microstructures of Additively Manufactured Ti6Al4V (Eli) by the Method of X-ray Diffraction." Materials 13, no. 23 (November 26, 2020): 5355. http://dx.doi.org/10.3390/ma13235355.

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Dislocations play a central role in determining strength and flow properties of metals and alloys. Diffusionless phase transformation of β→α in Ti6Al4V during the Direct Metal Laser Sintering (DMLS) process produces martensitic microstructures with high dislocation densities. However, heat treatment, such as stress relieving and annealing, can be applied to reduce the volume of these dislocations. In the present study, an analysis of the X-ray diffraction (XRD) profiles of the non-heat-treated and heat-treated microstructures of DMLS Ti6Al4V(ELI) was carried out to determine the level of defects in these microstructures. The modified Williamson–Hall and modified Warren–Averbach methods of analysis were used to evaluate the dislocation densities in these microstructures. The results obtained showed a 73% reduction of dislocation density in DMLS Ti6Al4V(ELI) upon stress relieving heat treatment. The density of dislocations further declined in microstructures that were annealed at elevated temperatures, with the microstructures that were heat-treated just below the β→α recording the lowest dislocation densities.

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Humnabad, Prashant S., R. Tarun, and Indraneel Das. "An Overview Of Direct Metal Laser Sintering (DMLS) Technology For Metal 3D Printing." Journal of Mines, Metals and Fuels 70, no. 3A (July 12, 2022): 127. http://dx.doi.org/10.18311/jmmf/2022/30681.

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<p>Additive manufacturing is the process of building a component or a product layer-by-layer, as opposed to casting the component and then performing various subtractive machining processes like turning, drilling, milling which are the approach of subtractive manufacturing. The term 3D printing refers to the family of additive manufacturing processes, which utilize different mechanisms in order to build the product from a sliced computer aided design (CAD) model fed to the machine. direct metal laser sintering (DMLS) is the one method of 3D printing functional metal parts are suitable for engineering applications and has the potential to provide a viable alternative to conventional methods of manufacturing and produce superior quality components with great flexibility in design using a wide range of materials. This paper presents the overview of DMLS technology, process parameters, design considerations, case studies of parts manufactured by DMLS and its applications in metal casting and rapid tooling.</p>

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Gu, Dongdong, and Yifu Shen. "Microstructures and properties of direct laser sintered tungsten carbide (WC) particle reinforced Cu matrix composites with RE–Si–Fe addition: A comparative study." Journal of Materials Research 24, no. 11 (November 2009): 3397–406. http://dx.doi.org/10.1557/jmr.2009.0419.

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The poor wettability between ceramics and metals is a main obstacle in obtaining high-performance metal-matrix composites (MMCs) parts using direct metal laser sintering (DMLS). Rare earth (RE) elements, due to their unique physical and chemical properties, have high potential for improving laser processability of MMCs. In this work, a comparative study was performed to investigate the influence of RE–Si–Fe addition on microstructural features and mechanical properties of DMLS processed tungsten carbide (WC) particle reinforced Cu MMCs parts. It showed that by adding 3 wt% RE–Si–Fe, the WC reinforcing particles were refined, the particle dispersion state was homogenized, and the particle/matrix interfacial compatibility was enhanced. The RE–Si–Fe-containing WC/Cu MMCs parts possessed significantly elevated mechanical properties, i.e., densification level of 95.7%, microhardness of 417.6 HV, fracture strength of 201.8 MPa, and friction coefficient of 0.8. The metallurgical functions of the RE–Si–Fe additive for the improvement of DMLS quality of MMCs parts were discussed.

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Daňa, Milan, Ivana Zetková, and Pavel Hanzl. "Printing of Thin Walls using DMLS." Manufacturing Technology 16, no. 5 (October 1, 2016): 883–89. http://dx.doi.org/10.21062/ujep/x.2016/a/1213-2489/mt/16/5/883.

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Petzoldt, F., H. Pohl, A. Simchi, and B. Alcantara. "DMLS gets an expert once-over." Metal Powder Report 61, no. 4 (April 2006): 10–13. http://dx.doi.org/10.1016/s0026-0657(09)70113-4.

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Fiuza, C., S. Fiuza, M. Aramfard, C. Deng, and R. França. "Physicochemical characterization of DMLS dental implants." Dental Materials 33 (2017): e31. http://dx.doi.org/10.1016/j.dental.2017.08.061.

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Băilă, Diana-Irinel, Răzvan Păcurar, Tom Savu, Cătălin Zaharia, Roxana Trușcă, Ovidiu Nemeș, Filip Górski, Ancuța Păcurar, Alin Pleșa, and Emilia Sabău. "Mechanical and Wetting Properties of Ta2O5 and ZnO Coatings on Alloy Substrate of Cardiovascular Stents Manufactured by Casting and DMLS." Materials 15, no. 16 (August 14, 2022): 5580. http://dx.doi.org/10.3390/ma15165580.

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In the last years, additive manufacturing technologies have been developed, especially direct metal laser sintering, and used in the dental and medical implant domains. Cardiovascular stents have evolved from bioinert, bare metal cages to biomimetic devices that promote tissue regeneration or healing. In this paper, comparisons concerning mechanical properties between Co–Cr alloy and cast 304L stainless steel were realized using FEM analysis, necessary for manufacturing cardiovascular stents by DMLS technology using Co–Cr alloy. The purpose of this paper consists of the evaluation of the contact angle at the interface of the Co–Cr alloy manufactured by DMLS, respectively, cast stainless steel 304L, and thin film deposition realized by the e-gun method (Ta2O5 and ZnO). Scanning electronic microscopy SEM and EDX techniques were employed for morphological investigation of the sintered samples manufactured by the DMLS process. They were also used for semi-quantitative and qualitative chemical and metallographic analyses. The e-gun coating was used to obtain thin films with the nanometer order of Ta2O5 and ZnO with a protective role to improve the corrosion resistance, roughness, and antiseptic role.

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Băilă, Diana-Irinel, Cătălin Vițelaru, Roxana Trușcă, Lidia Ruxandra Constantin, Ancuța Păcurar, Constantina Anca Parau, and Răzvan Păcurar. "Thin Films Deposition of Ta2O5 and ZnO by E-Gun Technology on Co-Cr Alloy Manufactured by Direct Metal Laser Sintering." Materials 14, no. 13 (June 30, 2021): 3666. http://dx.doi.org/10.3390/ma14133666.

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In recent years in the dental field, new types of materials and techniques for the manufacturing of dental crowns and analog implants have been developed to improve the quality of these products. The objective of this article was to perform the surface characterization and determine the properties of Co-Cr alloy samples fabricated by the direct metal laser sintering (DMLS) process and coated by e-gun technology with thin films of Ta2O5 and ZnO. Both oxides are frequently used for dental products, in pharmacology, cosmetics, and medicine, due to their good anticorrosive, antibacterial, and photo-catalytic properties. Following the deposition of thin oxide films on the Co-Cr samples fabricated by DMLS, a very fine roughness in the order of nanometers was obtained. Thin films deposition was realized to improve the hardness and the roughness of the Co-Cr parts fabricated by the DMLS process. Surface characterization was performed using SEM-EDS, AFM, and XRD. AFM was used to determine the roughness of the samples and the nanoindentation curves were determined to establish the hardness values and modulus of elasticity.

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Subrahmanyam, A. P. S. V. R., P. Srinivasa Rao, and K. Siva Prasad. "Enhancement of Surface Quality of DMLS Aluminium Alloy using RSM Optimization and ANN Modelling." Journal of Mechanical Engineering 18, no. 3 (September 15, 2021): 37–56. http://dx.doi.org/10.24191/jmeche.v18i3.15413.

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Direct Metal Laser Sintering (DMLS) is an additive manufacturing technology gaining popularity due to its ability to produce near net-shaped functional components. As there is a great need to improve the surface quality of DMLS components to upgrade their dynamic properties, an attempt was made to study the influence of process parameters like laser power, scan speed, and overlap rate on the surface quality of DMLS Aluminum alloy (AlSi10Mg) in as-built condition. The optimized process window to generate the best surface quality was achieved using Response Surface Method (RSM). Artificial Neural Network (ANN) modeling is also developed to map the influence of process parameters on surface quality. Conclusively, Scan speed is found to be most influential over surface quality as per the F and P test results. The optimized process parameters for best surface quality (3.52 µm) were 300 W laser power, 600 mm/sec scan speed, and 25% overlap rate. Both RSM and ANN models were accurate in prediction. However, ANN is recorded as superior with the highest coefficient of correlation (R).

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Siddiqui, Sanna F., and Ali P. Gordon. "Cyclic shear response of additively manufactured Inconel 718." Rapid Prototyping Journal 26, no. 7 (June 13, 2020): 1237–48. http://dx.doi.org/10.1108/rpj-09-2018-0243.

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Purpose Additive manufacturing (AM) studies on Inconel 718 (IN718) have focused on exploring its tensile and fatigue response. As IN718 is used in the propulsion and energy sector, the impact of shearing is also critical to ensuring the durability of these components. As such, this study aims to explore the relation between build orientation on the shear cyclic response of direct metal laser sintered (DMLS) IN718. Design/methodology/approach IN718 torsion specimens were manufactured along six build orientations: (100)-X, (010)-Y, (001)-Z, (110)-XY45, (101)-XZ45 and (011)-YZ45, using the DMLS process. Torsional fatigue testing was performed on as-built specimens, from which fracture behavior, surface roughness, softening/hardening response and monotonic/cyclic shear torsional properties were assessed. Findings DMLS IN718 was found to exhibit transversely isotropic behavior. In terms of shear stress range and shear modulus, Z > (X, XY45, Y) > (XZ45, YZ45). Specimens cyclically hardened to stabilization and softened to fracture. In terms of torsional fatigue fracture response, the Z, XZ45 and YZ45 specimens exhibited crack initiation and propagation from internal defects, whereas cracks were found to initiate at the surface and propagate between and through build layers for the X, Y and XY45 specimens. Originality/value This study reports the torsional cyclic response and shear moduli exhibited by as-built DMLS IN718 manufactured along varying build orientations. The findings are applicable for researchers because of the wide use of IN718 in the gas turbine industry, and the current trend to replace conventional manufacturing with AM.

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CORANIC, TOMAS. "DESIGN AND MANUFACTURING OF AN OPTIMIZED MOULD INSERT BY DMLS TECHNOLOGY." MM Science Journal 2021, no. 6 (December 15, 2021): 5492–96. http://dx.doi.org/10.17973/mmsj.2021_12_2021186.

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Utilization of the DMLS technology in manufacturing of tools and moulds designed for injection and casting ranks among significant possibilities of use. The main advantage in case of DMLS in comparison to conventional methods rests in the fact that manufacturing time does not depend on geometrical complexity of shaping part of the mould. In case of low volume or prototype moulds it is advantageous to use a concept of combination of shaping intermediate pieces inserted in universal frames and as material the DM 20 alloy on bronze basis the service life of which in case of such application is several thousand pieces.

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Jagadish, C. A., and Nadig Priyanka. "Effect of Cryogenic Treatment on the Mechanical Properties of 18Ni-300 Grade Maraging Steel Built Using the Direct Metal Laser Sintering (DMLS) Technology." Key Engineering Materials 719 (November 2016): 114–21. http://dx.doi.org/10.4028/www.scientific.net/kem.719.114.

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Maraging steels belong to the class of steels that are found to have a unique combination of ultra-high strength and good fracture toughness, due to which they find uses in critical applications such as aircraft forgings, pressure vessels, missile casings, hydraulic hoses etc. Several studies on the effect of cryogenic treatment on various grades of Tool steels & Maraging steels have shown significant improvements in mechanical properties and dimensional stability.DMLS (Direct Metal Laser Sintering), an additive manufacturing technology, is increasingly becoming popular to build intricate high quality functional parts & rapid prototypes. DMLS technology uses a high intensity laser to build components layer by layer, directly from CAD data without the need for tooling. It is possible to build internal features and passages that are not possible in conventional manufacturing routes. Maraging Steel is used extensively to build functional parts by DMLS process especially for Tool and Die applications. However, very few findings have been reported on the effect of cryogenic treatment on the mechanical properties of Maraging steel built through this route. In this study, effect of cryogenic treatment on Maraging Steel grade 300 built by DMLS process is discussed. Test specimens were built in horizontal and vertical directions to see the effect of build direction on the properties. Half the specimens were given standard DMLS precipitation hardening heat treatment and the rest were given cryogenic treatment in addition to routine thermal treatment. Mechanical properties such as - tensile, impact properties , hardness, & density between the two sets of treatments are reported and discussed. Metallurgical structures are compared and findings are also reported.

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Walker, Malz, Trudel, Nosir, ElSayed, and Kok. "Effects of Ultrasonic Impact Treatment on the Stress-Controlled Fatigue Performance of Additively Manufactured DMLS Ti-6Al-4V Alloy." Applied Sciences 9, no. 22 (November 8, 2019): 4787. http://dx.doi.org/10.3390/app9224787.

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Additive manufacturing (AM) offers many advantages for the mechanical design of metal components. However, the benefits of AM are offset to a certain extent by the poor surface finish and high residual stresses resulting from the printing process, which consequently compromise the mechanical properties of the parts, particularly their fatigue performance. Ultrasonic impact treatment (UIT) is a surface modification process which is often used to increase the fatigue life of welds in ship hulls and steel bridges. This paper studies the effect of UIT on the fatigue life of Ti-6Al-4V manufactured by Direct Metal Laser Sintering (DMLS). The surface properties before and after the UIT are characterized by surface porosity, roughness, hardness and residual stresses. Results show that UIT enhances the fatigue life of DMLS Ti-6Al-4V parts by suppressing the surface defects originating from the DMLS process and inducing compressive residual stresses at the surface. At the adopted UIT application parameters, the treatment improved the fatigue performance by 200%, significantly decreased surface porosity, reduced the surface roughness by 69%, and imposed a compressive hydrostatic stress of 1644 MPa at the surface.

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Singh, Ramandeep, Ashish Suri, Sneh Anand, and Britty Baby. "Validation of Reverse-Engineered and Additive-Manufactured Microsurgical Instrument Prototype." Surgical Innovation 23, no. 6 (July 9, 2016): 606–12. http://dx.doi.org/10.1177/1553350616656282.

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With advancements in imaging techniques, neurosurgical procedures are becoming highly precise and minimally invasive, thus demanding development of new ergonomically aesthetic instruments. Conventionally, neurosurgical instruments are manufactured using subtractive manufacturing methods. Such a process is complex, time-consuming, and impractical for prototype development and validation of new designs. Therefore, an alternative design process has been used utilizing blue light scanning, computer-aided designing, and additive manufacturing direct metal laser sintering (DMLS) for microsurgical instrument prototype development. Deviations of DMLS-fabricated instrument were studied by superimposing scan data of fabricated instrument with the computer-aided designing model. Content and concurrent validity of the fabricated prototypes was done by a group of 15 neurosurgeons by performing sciatic nerve anastomosis in small laboratory animals. Comparative scoring was obtained for the control and study instrument. T test was applied to the individual parameters and P values for force ( P < .0001) and surface roughness ( P < .01) were found to be statistically significant. These 2 parameters were further analyzed using objective measures. Results depicts that additive manufacturing by DMLS provides an effective method for prototype development. However, direct application of these additive-manufactured instruments in the operating room requires further validation.

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Gajera, Hiren M., Komal G. Dave, and Veera P. Darji. "Experimental Investigation and Optimization of Direct Metal Laser Sintered CL50WS Material Using Desirability Function Approach." Advanced Materials Research 1150 (November 2018): 43–58. http://dx.doi.org/10.4028/www.scientific.net/amr.1150.43.

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The aim of the this study to determine optimal process parameter for the hardness of direct metal laser sintering (DMLS) process as the hardness plays a significant role in to DMLS made components and die or mould. In this manner, research is focused around determining the effect of process parameters like laser power, scanning speed, layer thickness and hatch spacing on the hardness of CL50WS (maraging18Ni300 steel) material. A response surface methodology based numerical model was proposed to predict hardness, and the adequacy of the created model was checked through the analysis of variance technique. Additionally, optimized conditions were set up to maximize the hardness through the desirability function theory.

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Journal articles on the topic 'DMLS'

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