Geometric accuracy of models made using rapid prototyping methods. Part 1. Cylindrical and cuboidal elements

ObjectivesThe aim of this systematic review and network meta-analysis was to compare the flexural strength of provisional fixed dental prostheses (PFDPs) fabricated using different 3D printing technologies, including digital light processing (DLP), stereolithography (SLA), liquid crystal display (LCD), selective laser sintering (SLS), Digital Light Synthesis (DLS), and fused deposition modeling (FDM).Materials and methodsA comprehensive literature search was conducted in databases including PubMed, Web of Science, Scopus, and Open Grey up to September 2024. Studies evaluating the flexural strength of PFDPs fabricated by 3D printing systems were included. A network meta-analysis was performed, using standardized mean differences (SMDs) and 95% confidence intervals (CIs) to assess the effects of each system on flexural strength.ResultsA total of 11 in vitro studies were included, with 9 studies contributing to the network meta-analysis. SLS (77.70%) and SLA (63.82%) systems ranked the highest in terms of flexural strength, while DLP ranked the lowest (23.40%). Significant differences were observed between SLS and multiple other systems, including DLP (-14.58, CI: -22.67 to -6.48), LCD (-14.65, CI: -25.54 to -3.59), FDM (-12.87, CI: -23.30 to -2.52), SLA (-11.41, CI: -18.74 to -4.01), and DLS (-10.89, CI: -21.23 to -0.67). Direct comparisons were limited, with DLP vs. SLA having the most data. Other comparisons were predominantly indirect.ConclusionsSLS and SLA systems exhibited superior flexural strength compared to other systems. However, the limited number of direct comparisons and reliance on indirect evidence suggest that further research is necessary to confirm these findings.

The adoption of open-source digital manufacturing technologies in small art workshops may improve their competitiveness. Pieces modeled by computer and made with FDM (Fused Deposition Modeling) 3D printers that use PLA (polylactic acid) can be implemented in the procedures of artistic casting. However, models printed by PLA are limited to approximate minimum sizes of 3 cm, and the optimal layer height resolution is 0.1 mm. These sizes and resolutions are not suitable for creating microsculptures used, in many cases, in jewelry. An alternative to solve this limitation, is to use a DMLS (Direct Metal Laser Sintering) 3D printer. However, due to its high cost, it is a technology that is difficult to introduce in small artistic foundries. This work detailed the design and validation of a DLP (Digital Light Processing) 3D printer, using backlit LCD (Liquid Crystal Display) screens with ultraviolet light. Its development is totally “open source” and is proposed as a kit made up of electronic components, based on Arduino and easy to access mechanical components in the market. Most parts can be manufactured in low cost FDM (Fused Deposition Modeling) 3D printers. The result is an affordable, high resolution (0.021 mm), and open-design printer that can be implemented in artistic contexts.

In today's conditions, 3D printing is used to create unique models, prototypes, and equipment necessary for conducting experiments and studying various phenomena and processes, for the rapid prototyping of various parts and devices in scientific and engineering research. 3D printing technologies are actively used to create individual medical implants, prostheses, and organ models for training and planning operations, which significantly improves the quality of medical care. In the aerospace and automotive industries, additive manufacturing is used to create lightweight and durable parts helping to reduce weight and improve vehicle efficiency. The use of additive manufacturing methods, technologies, and tools allows you to check and test designs and concepts before mass production. In this work, a detailed analysis of various existing 3D printers is carried out depending on the tasks, and modern technologies of additive manufacturing are investigated depending on the set goals and scientific and applied tasks. Such technologies include Fused Deposition Modeling, Stereolithography, Selective Laser Sintering, Direct Metal Laser Sintering, and Digital Light Processing. In the work, a comparative analysis of these technologies was carried out according to various criteria, such as principle of operation, materials, resolution, surface finish, accuracy, speed, strength, application, cost, complexity of parts, and post-processing. For each technology, the advantages and disadvantages of its use are determined depending on the goals and objectives. It should be noted that some materials may not be suitable for printing complex parts or require additional support during the printing process. This can lead to complexity in the processing of products and increase the time and costs of printing. Improper selection of materials for 3D printing can be harmful to the environment or human health when used incorrectly. For example, some plastic materials may emit toxic elements or have low biodegradability. Also, using excess expensive material unnecessarily can increase the cost of the project. Keywords: additive manufacturing, 3D printing, additive manufacturing technologies, Fused Deposition Modeling, Stereolithography, Selective Laser Sintering, Direct Metal Laser Sintering, Digital Light Processing.

Thermal conductive composites for FDM 3D printing: A review, opportunities and obstacles, future directions

Milling-based, subtractive fabrication of digital complete dentures represents the computer-engineered manufacturing method of choice. However, efficient additive manufacturing technologies might also prove beneficial for the indication. The aim of the present study was to evaluate the accuracy of surface adaptation of complete denture bases fabricated using subtractive, additive, and conventional manufacturing techniques. A standardized edentulous maxillary model was digitally designed and milled. Twelve duplicated plaster casts were scanned and virtual denture bases designed accordingly. Physical complete denture bases (n = 12 per technique) were manufactured applying different digital and conventional fabrication methods: 1) CNC milling (MIL); 2) material jetting (MJ); 3) selective laser sintering (SLS); 4) digital light processing (DLP); and 5) conventional injection molding (INJ). The INJ group served as control. The intaglio surfaces of the denture bases were digitized and superposed with the surface data of the casts using a best-fit algorithm. Accuracy of surface adaptation was assessed by examining deviations. Statistical analysis was conducted using SPSS (P < 0.05). The milling of denture bases led to significantly better surface adaptation compared with all the other technologies (P < 0.001). The other fabrication methods in the study, including conventional manufacturing, revealed no considerable overall differences. As regards the accuracy of surface adaptation, all the investigated technologies adequately produced complete denture bases, with milled denture bases presenting the most superior results.

Comparison of DLP and LCD 3D printing technologies: effects on denture base accuracy, weight, residual material, resin consumption, and production time.

Purpose: The aim of this work was to define the influence of manufacturing technology on the chemical composition, surface topography, physicochemical and electrochemical properties of CoCr alloys obtained by casting technology and Direct Metal Laser Sintering. Design/methodology/approach: This work presents microstructural and chemical compositions obtained by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). Additionally, corrosion pitting analysis and roughness measurement were conducted on the samples. Findings: On the basis of the investigations, it can be stated that the prosthetic restorations are different depending on the type manufacturing technology. Based on the obtained results it was found that the structures of both materials are chemically inhomogeneous. The investigated alloy exhibited similar polarization curve character. Practical implications: The rapid prototyping methods are a new technology used for getting details e.g. by CAD/CAM procedure. Using Direct Metal Laser Sintering (DMLS) method can simplify the technology of producing prosthetics restrictions and is an alternate way for standard casting technology. Originality/value: The paper presents comparative research of two Co-Cr alloys, from which the samples were obtained in conventional casting and DMLS technology.

The field of three-dimensional (3D) printing has witnessed significant advancements in recent years, and its potential for revolutionizing medical applications is rapidly emerging. This review aims to provide an overview of the current state and scope of 3D printing in the medical field. The review begins by highlighting the various 3D printing technologies currently employed in healthcare settings, including stereolithography, selective laser sintering, fused deposition modeling, and inkjet printing. Each technology's advantages and limitations are discussed, shedding light on their suitability for different medical applications. Next, the review delves into the diverse range of medical applications where 3D printing has shown promise. These applications include the fabrication of patient-specific anatomical models for preoperative planning, surgical guides and tools, customized implants and prosthetics, tissue engineering scaffolds, and drug delivery systems. The potential benefits of using 3D printing in these areas, such as enhanced surgical accuracy, improved patient outcomes, reduced surgery time, and personalized medicine, are explored. Furthermore, the review addresses the challenges and limitations associated with implementing 3D printing in medical settings. These challenges include regulatory concerns, standardization of processes, material biocompatibility, cost-effectiveness, and scalability. The ongoing efforts to overcome these barriers and the future directions of 3D printing in medicine are also discussed. In conclusion, 3D printing holds immense potential for transforming various aspects of medical practice. While considerable progress has been made, there are still challenges to be addressed before widespread adoption can be achieved. With continued research and development, coupled with regulatory support and collaboration between academia, industry, and healthcare professionals, 3D printing is poised to International Journal of Scientific Research in Engineering and Management (IJSREM) Volume: 07 Issue: 07 | July - 2023 SJIF Rating: 8.176 ISSN: 2582-3930 © 2023, IJSREM | www.ijsrem.com DOI: 10.55041/IJSREM24845 | Page 2 make a substantial impact in the field of medicine, improving patient care and treatment outcomes. Key words: Additive manufacturing (AM); Bio-medical; Fused Deposition Modelling (FDM); Selective Laser Sintering (SLS); Stereolithography (SLA); Digital Light Processing (DLP); Binder Jetting; Material Jetting; Direct Energy Deposition (DED).

Technology of selective laser sintering / melting (SLS/SLM) is applied for manufacturing of net shaped objects from different powders : Inox 904L, Ni625, Cu/Sn, W. Experiments were carried out on PHENIX-100 machine : 50 W fibre laser, powder is spread by a roller over the surface of a build cylinder with 100 mm diameter.Width of laser sintered line from Inox 904L powder (powder layer thickness is 50 µm) on metallic substrate was studied applying different laser power P and beam velocity V (V=60-240mm/s) but keeping effective energy input constant P1/ V1∼P2/ V2. Accuracy of fabrication of thin walls and triangles applying different laser power and sintering velocity was studied. Critical beam velocity is defined when sintered lines start to be discontinuous and drops are produced.Different sintering strategies were applied and compared : (a) four different orientations of “vector” of beam displacement relatively given geometry of an object to be manufactured, (b) variation of distance between scanning lines, (c) application of different strategies to fabricate internal and external parts of an object. Performance and limitations of different strategies are analysed applying the following criteria : geometrical accuracy of fabrication, porosity, microhardness. Long term stability of SLM process was controlled by fabrication of thin walled objects during 36 hours. Finally the developed technology was applied for fabrication of parts for mechanical (mini pomp), medical (dental prosthesis, implants ?), bio-medical (diagnostic equipment) applications.The last part of the work was oriented for manufacturing of multi-material products. Two-component products (Stainless steel /Cu) with good material interface were fabricated in a two-step manufacturing cycle.Technology of selective laser sintering / melting (SLS/SLM) is applied for manufacturing of net shaped objects from different powders : Inox 904L, Ni625, Cu/Sn, W. Experiments were carried out on PHENIX-100 machine : 50 W fibre laser, powder is spread by a roller over the surface of a build cylinder with 100 mm diameter.Width of laser sintered line from Inox 904L powder (powder layer thickness is 50 µm) on metallic substrate was studied applying different laser power P and beam velocity V (V=60-240mm/s) but keeping effective energy input constant P1/ V1∼P2/ V2. Accuracy of fabrication of thin walls and triangles applying different laser power and sintering velocity was studied. Critical beam velocity is defined when sintered lines start to be discontinuous and drops are produced.Different sintering strategies were applied and compared : (a) four different orientations of “vector” of beam displacement relatively given geometry of an object to be manufactured, (b) variation of distance between scanning line...

Abstract3D printing manufacturing technology has garnered a lot of interest in recent years to simplify the fabrication of complex geometries and for its ability to work with a wide range of materials including but not limited to metals, ceramics, polymers, and composites. It also reduces the amount of material required and opens up the scope to print composites that are highly specific to the desired mechanical properties. This review article gives an overview of the common 3D printing methods such as fused deposition modeling, selective laser sintering, stereolithography, and digital light processing. Additionally, it focuses on the 3-D printer materials, the scope of the 3D printed parts and discusses the limitations of each technique in order to encourage further research in this field.KeywordsSelective Laser Sintering (SLS)Stereolithography (SLA)Fused Deposition Modeling (FDM)Digital Light Processing (DLP)Acrylonitrile Butadiene Styrene (ABS)Poly Lactic Acid (PLA)

At present there are various methods of rapid prototyping. Different physical processes and materials for making prototypes are employed: stereo-lithography - layered hardening of liquid monomers with UV-laser beam trough light influence: LOM method employs sheet materials cut with laser beams; FDIVI-method - layered covering of melted polymer fibers; selective laser sintering - SLS. At the last process prototypes are made from sintered powder materials under thermal effect of laser beam.

This review article provides a deep dive into the diverse landscape of Additive Manufacturing (AM) technologies and their significant impact on the automotive and aviation sectors. It starts by exploring various AM methodologies such as Fused Deposition Modeling (FDM), Stereolithography (SLA), Digital Light Processing (DLP), Selective Laser Sintering (SLS), Metal Jet Fusion (MJF), Binder Jetting (BJ), and Directed Energy Deposition (DED), with a specific focus on their applicability, strengths, and challenges within these industries. The article then delves into the practical applications of AM in rapid prototyping, functional part production, and component repair. The results highlight the versatility and precision of SLA and DLP, the strength and durability of SLS, and the potential of metal-based technologies like LPBF, SLM, EBM, and DMLS in manufacturing critical components. The integration of AM with automotive and aviation design underscores the transformative nature of these technologies, driving advancements in lightweight, intricate, and high-performance components. The review concludes by emphasising AM's significant opportunities and acknowledging the ongoing challenges in material properties, post-processing, and production scalability, thereby underscoring the necessity for future research and innovation in these sectors.

3D printing, also known as additive manufacturing, allows the creation of various products, including membrane elements made of different materials, namely polymers, metals, ceramics, etc., ensuring the production of elements with complex and desired geometries. This article proposes to consider the prospects and possibilities of additive technologies for the commercial production of ceramic membranes and membrane modules. The purpose of this work is to present the prospects, opportunities, and challenges of using 3D printing, in particular digital light processing (DLP) and selective laser sintering (SLS), to obtain ceramic membranes and membrane modules. A comparison of traditional methods of ceramic membrane production with additive technologies was carried out and shows that 3D printing is a promising area of development. It is already changing the field of membrane technologies. Analysis of the literature shows that additive technologies allow the creation of more efficient, customized, and multifunctional membranes, which is particularly relevant for high-tech industries. It has been shown that the quality of ceramic membranes obtained by DLP or SLS printing depends on the choice of ceramic material, the optimal settings of the slicer (software for preparing the model for printing), its calibration, and control of printing parameters such as temperature, printing speed, and others. In addition, the quality of printed parts is influenced by model preparation, the specifics of a particular printing technology, resolution, and much more. Despite the existing problems and challenges, both technologies are moving towards mass production and application: 3D printing will allow the production of ceramic membranes for micro-, ultra- and nanofiltration with optimized internal structures, which will increase filtration efficiency and reduce fouling.

Purpose: Success and safety of dental implants requires accurate treatment planning andprecise implant placement. There should be no deviation between the virtually planned implantposition and the actual implant position after the implant installation regardless the technique ofconstruction of the surgical-guide. So this study was to evaluate and compare the accuracy of twodifferent CAD/CAM surgical guides in placement of all-on-4 implants. Materials and methods:A prospective randomized controlled double blind clinical study was carried out, in which twentyfour implants were placed in 6 edentulous patients. Patients were randomly allocated into one of thetwo groups: control group where surgeries were done using digital light processing (DLP) surgicalguidesand study group where implants were placed using selective laser sintering (SLS) surgicalguides.Each patient received 4 implants in the anterior part of the mandible, 2 axial implants in thecenter and 2 tilted implants at the distal ends. CBCT were taken to the implants after the surgery andthe actual implant positions were compared to the planned implant position. The deviation betweenthe planned and actual implant positions were compared between the 2 techniques of surgical guideconstructions. Results: The results of comparison between the two groups showed a statisticallysignificant difference for all comparisons, with the SLS fabricated guides showing higher deviationfrom control than those fabricated by the DLP printer.Conclusion: Although the computer manufactured surgical guides simplifies surgery and helpin optimal implant placement, there is still evidence of degree of deviation from the planned implantspositions in both of the surgical guides, particularly the SLS fabricated guides so a safety zone so asafety zone is recommended during planning to avoid to avoid critical anatomical structures.

The SLS additive manufacturing industry enables the development of products for diverse applications with distinct properties due to its excellent surface finish and ability to create varied part geometries, but it consumes high-performance materials with high acquisition costs. An extensive quarrying of stone leads to the accumulation of mineral residues, posing environmental hazards by contaminating soil and water when disposed of in landfills. The primary objective of the study was to incorporate mineral waste into the SLS technique and investigate the influence of its addition, along with a silane-based chemical treatment, on the mechanical performance of polymer-mineral composites (PA12-slate). Additionally, the feasibility of producing a highly loaded printed prototype, employing 50 wt% of mineral waste, was examined. Samples of PA12, PA12 blended with 50 wt% slate waste, and slate waste treated with silane underwent fabrication via selective laser sintering (SLS) and subsequent mechanical characterization, including tensile, flexural, and compressive tests. Additionally, the samples underwent accelerated aging using a QUV weathering tester, followed by mechanical characterization. The geometric accuracy, stability, and processing feasibility of these formulations were evaluated through SLS-printed composite prototypes utilizing PA12_50Sla_Si. It was found that the addition of 50% of slate to the PA12 presented mechanical properties decreasing compared to the printed PA12 only. However, an increase was verified when using silane-induced mineral bonding. The incorporation of mineral agents and silane enhanced the resistance of PA12 to aging. However, after aging, both tensile and flexural strength decreased across all printed samples. Nonetheless, this study showcased the feasibility of producing complex PA12-slate waste specimens containing up to 50 wt% of mineral waste using the SLS printing technique. Therefore, SLS presents itself as a viable means of adding value to this mineral waste.