Innovative Manufacturing Technology Research Articles

Direct Melt-Calendaring of Highly Textured (Bi,Sb)2Te3 Thick Films: Superior Thermoelectric and Mechanical Performance via Strain Engineering.

The evolutions of chip thermal management and micro energy harvesting put forward urgent need for micro thermoelectric devices. Nevertheless, low-performance thermoelectric thick films as well as the complicated precision cutting process for hundred-micron thermoelectric legs still remain the bottleneck hindering the advancement of micro thermoelectric devices. In this work, an innovative direct melt-calendaring manufacturing technology is first proposed with specially designed and assembled equipment, that enables direct, rapid, and cost-effective continuous manufacturing of Bi2Te3-based films with thickness of hundred microns. Based on the strain engineering with external glass coating confinement and controlled calendaring deformation degree, enhanced thermoelectric performance has been achieved for (Bi,Sb)2Te3 thick films with highly textured nanocrystals, which can promote carrier mobility over 182.6 cm2 V-1 s-1 and bring out a record-high zT value of 0.96 and 1.16 for n-type and p-type (Bi,Sb)2Te3 thick films, respectively. The nanoscale interfaces also further improve the mechanical strength with excellent elastic modules (over 42.0GPa) and hardness (over 1.7GPa), even superior to the commercial zone-melting ingots and comparable to the hot-extrusion (Bi,Sb)2Te3 alloys. This new fabrication strategy is versatile to a wide range of inorganic thermoelectric thick films, which lays a solid foundation for the development of micro thermoelectric devices.

Applications and Advancement of 3D Printing in Pharmaceutical Manufacturing and Drug Delivery

Three-dimensional (3D) printing is an innovative additive manufacturing technology that has tremendous potential to revolutionize various aspects of the pharmaceutical industry including drug development, product design, manufacturing and delivery. 3D printing enables precise fabrication of complex drug products with customized compositions and geometries that cannot be produced through conventional processes. It facilitates rapid prototyping thereby accelerating drug development process. 3D printed dosage forms with capability of controlled, delayed and triggered drug release have potential to enhance patient compliance and therapeutic outcomes. Further, 3D printed personalized medications tailored to individual patient needs hold promise to improve medication accessibility and efficacy. Though 3D printing in pharmaceuticals is still in its infancy, ongoing research efforts aim to address key challenges including regulatory compliance, process optimization, material characterization and scale-up. As the technology advances further, 3D printing is expected to significantly transform pharmaceutical manufacturing by making on-demand, decentralized production a reality

Potential of 3D Printing for Heat Exchanger Heat Transfer Optimization—Sustainability Perspective

In just a few short years, the additive manufacturing (AM) technology known as 3D printing has experienced intense growth from a niche technology to a disruptive innovation that has captured the imagination of mainstream manufacturers and hobbyists alike. The purpose of this article is to introduce the use of 3D printing for specific applications, materials, and manufacturing processes that help to optimize heat transfer in heat exchangers, with an emphasis on sustainability. The ability to create complex geometries, customize designs, and use advanced materials provides opportunities for more efficient and stable heat transfer solutions. One of the key benefits of incremental technology is the potential reduction in material waste compared to traditional manufacturing methods. By optimizing the design and structure of heat transfer components, 3D printing enables lighter yet more efficient solutions and systems. The localized manufacturing of components, which reduces the need for intensive transportation and associated carbon emissions, can lead to reduced energy consumption and improved overall efficiency. The customization and flexibility of 3D printing enables the integration of heat transfer components into renewable energy systems. This article presents the key challenges to be addressed and the fundamental research needed to realize the full potential of incremental manufacturing technologies to optimize heat transfer in heat exchangers. It also presents a critical discussion and outlook for solving global energy challenges through innovative incremental manufacturing technologies in the heat exchanger sector.

Advancements in Lightweight Materials for Aerospace Structures: A Comprehensive Review

The aerospace engineering field is witnessing an evolution towards lightweight materials driven by the unwavering pursuit of improved performance and efficiency. Lightweight materials play a critical role in aerospace structures, and this thorough examination explores their significant influence on mission success, design, and fuel efficiency. Key developments in several material categories such as composites, metals, and polymers are methodically examined in this study, revealing their special qualities and potential uses. The historical viewpoint lays out a chronology of the development of materials, charting significant turning points that have influenced the use of lightweight materials in aerospace. The following sections delve into each lightweight material in great detail, explaining composites, alloys (including titanium, aluminium, and high-strength steel), and sophisticated polymers, along with their features, production methods, and uses. An examination of particular varieties and production nuances in the context of aerospace composite materials highlights their benefits in achieving unmatched strength-to-weight ratios. By elucidating their qualities and expanding uses in aircraft constructions, advanced metallic alloy research reveals the most recent advancements in materials like titanium and aluminium. A thorough examination of polymeric materials and nanocomposites reveals their critical role in the creation of lightweight structures. Their distinctive qualities and new uses are emphasized, highlighting their role in the ongoing revolution in aeronautical design. With a comprehensive examination of additive manufacturing and sophisticated machining methods essential to the realization of lightweight aircraft structures, innovative manufacturing technologies take center stage. Additionally, the assessment thoroughly evaluates the longevity and structural integrity of lightweight materials, addressing issues related to corrosion, fatigue, and other crucial elements. Investigations from actual applications provide concrete instances of lightweight materials being successfully used in aerospace projects, shedding light on the materials' performance and tangible advantages in various situations. Looking ahead, the paper's conclusion forecasts forthcoming developments in lightweight materials and clarifies possible obstacles and future research avenues that may influence the course of aerospace engineering. To underscore the critical role that lightweight materials play in aeronautical constructions, this paper synthesizes a variety of knowledge. It highlights the revolutionary potential of lightweight materials in influencing the future of aeronautical engineering, not only synthesizing current knowledge but also laying out a path for further study and innovation.

Experimental investigation on a lightweight, efficient, counter-rotating fan with and without boundary layer ingestion

AbstractThe experimental investigations on the counter-rotating CRISPmulti fan with boundary layer ingestion are presented in this paper. The Counter Rotating Integrated Shrouded Propfan (CRISP) was designed, aerodynamically optimized and manufactured in lightweight material by the German Aerospace Center (DLR). The main task was to maximize the aerodynamic efficiency under restricted static, dynamic and acoustic properties of the blade designed with lightweight carbon-fiber material and to apply it as a demonstrator for the development of a new innovative blade manufacturing technology. The rotors were manufactured at the DLR Institute of Structures and Design and tested on the Multi-stage 2-shaft Compressor Test Facility (M2VP) at the DLR Institute of Propulsion Technology. The instrumentation enabled the measurement of the aerodynamic, static, dynamic and acoustic behavior of the fan. In general, the targets of the experimental investigation were to validate the optimization results, the numerical calculational methods and the acoustic tools. Additionally, inlet distortion measurements were carried out on the fan rig to investigate the effect of the boundary layer ingestion on a real counter-rotating propfan. A radially traversable disturbance body, designed to simulate the boundary layer of the aircraft fuselage on an aircraft architecture with embedded engines, enables a comprehensive measurement program to be carried out for both undisturbed and disturbed inflow.

Emerging Multiscale Biofabrication Approaches for Bacteriotherapy.

Bacteriotherapy is emerging as a strategic and effective approach to treat infections by providing putatively harmless bacteria (i.e., probiotics) as antagonists to pathogens. Proper delivery of probiotics or their metabolites (i.e., post-biotics) can facilitate their availing of biomaterial encapsulation via innovative manufacturing technologies. This review paper aims to provide the most recent biomaterial-assisted strategies proposed to treat infections or dysbiosis using bacteriotherapy. We revised the encapsulation processes across multiscale biomaterial approaches, which could be ideal for targeting different tissues and suit diverse therapeutic opportunities. Hydrogels, and specifically polysaccharides, are the focus of this review, as they have been reported to better sustain the vitality of the live cells incorporated. Specifically, the approaches used for fabricating hydrogel-based devices with increasing dimensionality (D)-namely, 0D (i.e., particles), 1D (i.e., fibers), 2D (i.e., fiber meshes), and 3D (i.e., scaffolds)-endowed with probiotics, were detailed by describing their advantages and challenges, along with a future overlook in the field. Electrospinning, electrospray, and 3D bioprinting were investigated as new biofabrication methods for probiotic encapsulation within multidimensional matrices. Finally, examples of biomaterial-based systems for cell and possibly post-biotic release were reported.

Application of 4D printing in dentistry: A narrative review.

4D printing is an innovative digital manufacturing technology that originated by adding a fourth dimension, i.e., time, to pre-existing 3D technology or additive manufacturing (AM). AM is a fast-growing technology used in many fields, which develops accurate 3D objects based on models designed by computers. Dentistry is one such field in which 3D technology is used for manufacturing objects in periodontics (scaffolds, local drug-delivering agents, augmentation of ridges), implants, prosthodontics (partial and complete dentures, obturators), oral surgery for reconstructing jaw, and orthodontics. Dynamism is a vital property needed for the survival of materials used in the oral cavity since the oral cavity is constantly subjected to various insults. 4D printing technology has overcome the disadvantages of 3D printing technology, i.e., it cannot create dynamic objects. Therefore, constant knowledge of 4D technology is required. 3D printing technology has shortcomings, which are discussed in this review. This review summaries various printing technologies, materials used, stimuli, and potential applications of 4D technology in dentistry.

Review on High-Energy Beam Based Processing Technologies for Fabrication of Small Modular Reactor

The development of small modular reactors (SMRs) has attracted significant attention owing to the increasing interest in energy security and carbon neutrality worldwide. An SMR is an advanced nuclear reactor with a power capacity of up to 300 MWe per unit. To fabricate the SMR, innovative manufacturing technologies such as powder metallurgy hot isostatic pressing (PM-HIP), electron beam welding (EBW), and diode laser cladding (DLC) were introduced to reduce the fabrication cost and time. Particularly, this replaced arc-based welding and cladding with high-energy beam-based EBW and DLC. The EBW could provide one pass welding for extremely thick specimens. In addition, in the case of using the DLC, only one layer cladding was acceptable for corrosion protection owing to its low dilution rate. However, studies on the innovative manufacturing technologies were less reported because of technology security. In this study, recently reported research articles regarding the EBW and DLC were reviewed. In particular, local vacuum and reduced pressure electron beam studies were discussed by comparing their the arc welding results. Process parameter studies on the DLC were also reviewed to introduce appropriate optimized conditions for the industry application.

Barriers to sustainable innovation adoption: A qualitative investigation of metal additive printing from supply and demand perspectives

Metal additive printing (MAP) is an innovative manufacturing technology with promising sustainability performance standards, including increased supply chain efficiency and responsiveness. Yet, while MAP offers some sustainable advantages over other manufacturing methods, it faces various barriers to widespread adoption. This study used a qualitative research methodology to generate an in-depth understanding of the perceived barriers to MAP adoption. It explored the perspectives of various stakeholders, including MAP researchers and machine manufacturers (supply side), as well as end users (demand side) via 40 in-depth interviews. Study participant responses were analysed using thematic analysis and NVivo to identify key barrier themes and sub-themes. The findings revealed seven main barrier categories: production constraints, quality and standards, cost, social conservatism, education and skills, bureaucratic inertia, and marketing and distribution. Further analysis of these findings generated a unique framework that depicts MAP adoption barriers from both the supply and demand perspectives. This framework can help researchers, manufacturers and marketers to systematically categorise and evaluate MAP adoption barriers and identify ways to overcome them.

Innovations in cooking technologies using non-traditional raw materiais

The priority direction of the development of food industries of the 21st century is the production of healthy-prophylactic, functional purpose food, which get due to using the innovation technologies and also the use of non- traditional plant raw materials, including the wild plants, with the aim improving the qualitative adequacy of food rations namely ensuring compliance their chemical composition to the physiological needs of human body, improvement of their taste, aroma and other properties. Nowadays, the action of biologically active substances of plant origin for the creation of dishes with a health-improving, preventive functional effect remains insufficiently studied. Therefore, one of new recipes with an improved composition of raw materials, and also using new methods of processing and preparation of products which will allows to keep all nutrients and enriching the body with the necessary nutrients. In this context, in order to expand the range of dishes, we searched for non-traditional raw materials with a significant content of biologically active substances among the biodiversity of the vegetation of the Carpathian region and improved the technologies for the introduction them into Ukrainian cuisine. The properties of non-traditional raw materials of local origin are considered and proposed the priority of directions its use in the development of dishes with health-improving properties for sanatorium – resort complex and restaurants. Changes have been made to innovative manufacturing technologies dishes using traditional vegetable raw materials. Llingonberry and cranberry berries, and green leaves of stinging nettle were used as innovative ingredients taken to improve and expand the assortment of dishes with health-improving properties. Using innovative ingredients with the application of high technologies expands the possibilities of obtaining a technologically new product enriched with biologically active substances, macro- and micronutrients, vitamins, dietary fibers, and other functional additives. The nutritional and biological value of food products using unconventional raw materials of plant origin is given, and the priority directions of its use in the development of dishes with health-improving properties for sanatorium-resort complexes and restaurant establishments of the Western region of Ukraine are proposed.

Numerical modelling of 3D concrete printing: material models, boundary conditions and failure identification

3D concrete printing (3DCP) attracts significant attention as an innovative manufacturing technology for the construction industry. As one of the challenges in 3DCP, failure mechanisms of 3D printed concrete structures were not well understood yet and hard to predict. The three-dimensional finite element (FE) method is an effective method to simulate such a layer-by-layer process. However, some existing technical issues in FE modelling, including additional initial deformations, failure identification, selection of material models, concrete foundation interactions and initial imperfections, need to be addressed for accurate simulation of 3DCP. In this study, FE models using a novel tracing element approach are developed to capture mechanical behaviours and failure modes of typical 3D printed concrete structures. The developed FE models was validated by comparing the obtained numerical results with those data available in literature. Furthermore, four material constitutive models are investigated analytically and numerically to compare their applicability in modelling 3D printed concrete structures. The obtained results show that the Mohr-Coulomb and Concrete Damage Plasticity (CDP) models can accurately predict failure behaviours of 3D printed concrete structures.

Special Issue on Recent Progress in Precision Engineering

In recent years, the field of manufacturing has become increasingly diversified and complex to meet various requirements, such as improved manufacturing accuracy, productivity, environmental friendliness, and automation/intelligence in manufacturing sites. Consequently, the fusion of different fields as well as interdisciplinary research has become indispensable for the creation of innovative manufacturing technologies that can realize advanced production systems. This special issue comprises seven outstanding research papers that focus on advanced precision engineering in manufacturing systems, covering the following topics: - Advanced cutting technologies - Advanced machine tools and elements - Surface finishing technologies - Non-traditional machining and additive manufacturing - Nano-scale surface finishing - Advanced surface processing All research papers were originally presented at the 19th International Conference on Precision Engineering (ICPE2022), held in Nara, Japan, in 2022. The editors hope that the research papers included in this special issue will offer valuable insights to readers for their future research in the field of manufacturing technology. Each paper underwent a rigorous peer-review process, and the editors would like to express their deep appreciation for the efforts and excellent work of all the authors and anonymous reviewers who contributed to the realization of this special issue. Finally, it is our sincere hope that the papers in this special issue will further contribute to the advancement of our future society.

Investigation on the microstructures, mechanical properties and impact initiation characteristics of Al/PTFE reactive materials reinforced by TiH2 particles

Aluminum/Polytetrafluoroethylene (Al/PTFE) is a representative energetic material, which can be used in many fields including defense weapon fragments, insensitive penetrator or oil-well perforation. However, the insufficient mechanical strength of traditional ingredient has seriously restricted its penetration ability, and traditional additives improve its compressive strength at the expense of reactivity. Hence, innovative component design and advanced manufacturing technology should be applied to Al/PTFE composite. In this investigation, TiH2 as a new reinforcement is introduced into Al/PTFE to improve both strength and reactivity. Quasi-static and dynamic compressive tests were conducted, and the impact reaction process was recorded by high-speed camera. The results shown Al/PTFE/TiH2 composites are all elasto-plastic materials, significant strain hardening and strain rate hardening phenomenon were observed. The compressive strength increased first and then decreased with increase in TiH2 content, reached the maximum of 185.1 MPa at the strain rate of 5000 s−1 when TiH2 content was 30 %, which increased by 30.4 % compared to traditional Al/PTFE. A newly-developed drop-weight device was used to quantitatively characterize reactivity, and the reaction efficiency reached 8.2 % when TiH2 content was 30 %, increased by 43.2 % compared to Al/PTFE. The formation of oriented PTFE nano-fibers was considered the important strengthening mechanism. The established Johnson–Cook model was agreed well with experimental results. Combining the results of thermogravimetry-differential scanning calorimetry (TG-DSC) tests with X-ray diffraction (XRD) analysis of reaction residues, the reaction mechanism was clarified. The impact initiation reaction was in a mechano-chemical manner and the reactivity was speculated to be the results of multiple actions between Al/PTFE and TiH2.

4D Printing Shape-Morphing Hybrid Biomaterials for Advanced Bioengineering Applications.

Four-dimensional (4D) printing is an innovative additive manufacturing technology used to fabricate structures that can evolve over time when exposed to a predefined environmental stimulus. 4D printed objects are no longer static objects but programmable active structures that accomplish their functions thanks to a change over time in their physical/chemical properties that usually displays macroscopically as a shapeshifting in response to an external stimulus. 4D printing is characterized by several entangled features (e.g., involved material(s), structure geometry, and applied stimulus entities) that need to be carefully coupled to obtain a favorable fabrication and a functioning structure. Overall, the integration of micro-/nanofabrication methods of biomaterials with nanomaterials represents a promising approach for the development of advanced materials. The ability to construct complex and multifunctional triggerable structures capable of being activated allows for the control of biomedical device activity, reducing the need for invasive interventions. Such advancements provide new tools to biomedical engineers and clinicians to design dynamically actuated implantable devices. In this context, the aim of this review is to demonstrate the potential of 4D printing as an enabling manufacturing technology to code the environmentally triggered physical evolution of structures and devices of biomedical interest.

Special Issue on the Latest Machine Tool and Manufacturing Technologies

The social demands for manufacturing systems are constantly changing with the times. In recent years, environmental and social issues have been complicating these demands. For example, all industrial sectors need to consider environmentally responsible ways to achieve sustainable development goals in a time of paradigm shifts. The demands in the manufacturing field include high productivity, high quality, low energy consumption, and help for aging operators. To meet these various demands for manufacturing systems, we must create innovative manufacturing technologies to realize advanced production systems. This special issue focuses on state-of-the-art machine tools and manufacturing technologies to accelerate production engineering innovation. This issue consists of eleven research papers covering the following fields. - Advanced structure and drive systems in machine tools - Industrial robot applications - Advanced cutting technologies - Evaluation and calibration technologies of motion error - Surface finishing technologies - Grinding of hard and brittle materials All of these research contributions were presented at IMEC2022, a joint event with JIMTOF2022, held in Tokyo, Japan in 2022. I would like to sincerely thank all the authors for their contributions, and I sincerely hope that the papers in this special issue further contribute to the development of our future society.

A Study on the Wake Evolution of a Set of RIM-Driven Thrusters

In the current paper, high-fidelity improved delayed detached-eddy simulations (IDDES) using the OpenFOAM library are employed to characterize the performances and the wake dynamics of RIM-driven thrusters. Despite their relatively old conception, this type of propulsors has gained attention only recently thanks to innovative manufacturing technologies and materials, which finally have made possible their practical implementation. Fostered by stringent regulations on radiated noise and emissions enforced in protected areas, they are also replacing conventional thrusters and main propulsors. By mitigating the tip vortex cavitation and, more in general, by reducing the strength of tip vortices, indeed, these propulsors may grant a reduction in the induced pressure pulses and of the radiated noise without excessively sacrificing the efficiency of the equivalent ducted propellers they replace. To provide proof of this, three different RIM-driven thrusters (one four-bladed, two six-bladed) are analyzed and compared to a reference decelerating ducted propeller delivering the same thrust at identical functioning conditions. The evolution of the trailing wakes of the propulsors, the role of the leakage vortex, and the nozzle wake destabilizing effects, are highlighted, and the superior performances of RIM-driven thrusters, in terms of less intense tip vortices, are discussed. Near-field pressure pulses, as a measure of the radiated noise, are compared, showing a reduction in the sound pressure levels of the selected RIM propulsors up to 15 dB (non-cavitating case) with respect to the reference ducted propeller.

Characterization of Microchannels Produced by Friction Stir Channeling: An Experimental Study

Friction Stir Channeling (FSC) is a recent and innovative solid state manufacturing technology that allows, in a single pass, the opening of continuous internal channels in monolithic components and can be used in the mold and heat exchanger industries. However, the development of reliable Non-Destructive Testing (NDT) for the characterization of the channels is a major challenge. The focus of this work is the non-destructive characterization of micro channels, and the main goal was to experimentally validate which NDT techniques can be used to identify the presence of microchannels, their regularity along the section, and also their location, size, and path. Five NDT techniques were studied: digital radiology; eddy currents; ultrasounds; thermography; and dye penetrants. These techniques were applied to specimens with linear and curvilinear channels. The specimens were produced using tool pins with 0.5 mm diameter which obtained channels with 0.4 mm width and depths of 0.53 mm. Digital radiology and ultrasounds were effective in detecting channels regardless of its dimensions. Eddy currents did not allow to confirm the exclusive presence of the channels due to microstructural changes caused by the FSC process. Thermography using cold fluid injection was not successful in the channel’s characterization due to the extremely low flow. The dye penetrants confirmed the presence of the channels of all dimensions due to the liquid having traveled along the entire path of the curvilinear channel without reaching the surface.

Recent patent-based review on the role of three-dimensionalprinting technology in pharmaceutical and biomedical applications.

Three-dimensional printing (3DP) is emerging as an innovative manufacturing technology for biomedical and pharmaceutical applications, since the USFDA approval of Spritam as a 3D-printed drug. In the present review, we have highlighted the potential benefits of 3DP technology in healthcare, such as the ability to create patient-specific medical devices and implants, as well as the possibility of on-demand production of drugs and personalized dosage forms. We havefurther discussed future research to optimize 3DP processes and materials for pharmaceutical and biomedical applications. Cohesively, we have put forward the current state of active patents and applications related to 3DP technology in the healthcare and pharmaceutical industries including hearing aids, prostheses, medical devicesand drug-delivery systems.

Fabrication of Fe–30Al alloy using plasma arc welding powered twin-wire directed energy deposition-arc process: Droplet transfer, microstructure, and mechanical property investigation

Intrinsic brittleness and cold cracking sensitivity of Fe–Al intermetallic compounds make their fabrication and processing difficult. In recent years, an innovative additive manufacturing (AM) technology, twin-wire directed energy deposition-arc (TW-DED-arc), has been developed to prepare defect-free Fe–Al alloys via in-situ alloying of Fe and Al elements in a gas tungsten arc welding (GTAW) generated molten pool. However, unconstrained plasma of regular tungsten arc leads to excessive heating area and residual stress during AM buildup. And relatively weak arc pressure of GTAW makes composition inhomogeneity a concern in the in-situ alloying molten pool. To solve the two potential drawbacks, plasma arc welding (PAW) possessing higher energy density and arc pressure is used to power the TW-DED-arc process and fabricate Fe–30Al alloy. In the present research, a special wire-feeding strategy for stable twin-wire feeding of Fe and Al wires is successfully developed to overcome the droplet transfer difficulty induced by constrained arc of PAW and large thermophysical properties difference of heterogeneous filler wires. And according to microscopy characterization results, the innovative PAW powered TW-DED-arc process is capable of fabricating defect-free Fe–30Al bulk sample with homogeneous Al content and epitaxial columnar grain structures. The successful application of PAW-powered TW-DED-arc technique in fabrication of iron aluminide provides stabler and more efficient route for iron aluminide component.

Marginal and internal discrepancies associated with carbon digital light synthesis additively manufactured interim crowns

Statement of problemThe carbon digital light synthesis (DLS) or continuous liquid interface production (CLIP) technology is an innovative additive manufacturing technology using oxygen-inhibited photopolymerization to create a continuous liquid interface of unpolymerized resin between the growing component and the exposure window. This interface eliminates the need for an incremental layer-by-layer approach, allowing for continuous creation and increased printing speed. However, the internal and marginal discrepancies associated with this new technology remain unclear. PurposeThe purpose of this in vitro study was to evaluate the marginal and internal discrepancies by using the silicone replica technique of interim crowns fabricated by 3 different manufacturing technologies: direct light processing (DLP), DLS, and milling. Material and methodsA mandibular first molar was prepared, and a crown was designed with a computer-aided design (CAD) software program. The standard tessellation language (STL) file was used to create 30 crowns from the DLP, DLS, milling technologies (n=10). The gap discrepancy was determined using the silicone replica approach, with 50 measurements made with a ×70 microscope for each specimen for the marginal and internal gaps. The data were analyzed using 1-way ANOVA, followed by the Tukey HSD post hoc test (α=.05). ResultsThe DLS group had the least marginal discrepancy compared with the DLP and milling groups (P<.001). The DLP group showed the highest internal discrepancy followed by the DLS and milling groups (P=.038). No significant difference was found between DLS and milling in terms of internal discrepancy (P>.05). ConclusionsThe manufacturing technique had a significant effect on both internal and marginal discrepancies. The DLS technology showed the smallest marginal discrepancies.