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Purpose: Conventional powder bed fusion systems, with their high costs, proprietary nature and restrictive fees, limit research opportunities. This study aims to unveil an affordable, open-source hardware, open-source software laser-based metal powder bed fusion system. Recognizing the distinction between DIY and open-source hardware is crucial for widespread acceptance. Design/methodology/approach: The authors present a comprehensive system architecture using object process methodology for functions and architecture, a design structure matrix to model system dependencies and classical technical drawing exploded views for select subsystems. Modularization enables high adaptability, fostering potential adoption. Findings: The fully open system enables unrestricted research, mirroring common industrial metal laser-based powder bed fusion (L-PBF) systems. While "open" systems are available for purchase, they remain closed-source, lacking source code and technical drawings sharing, hindering contribution and co-development. The authors' is the pioneering and sole open-source metal L-PBF system, boasting 1,500+ print hours. A series of industrial and academic adopters are currently implementing the system. Originality/value: The open system, slicer software and controller offer unique process control, supporting multimaterial printing. The authors shared the design on the OpenAM GitHub page under the CERN-OHL-P v2 Open Source Hardware license. While it is functional for additive manufacturing (e.g. aluminum, tool steel, titanium and stainless steel), the entire process chain is actively evolving, ideal for co-development with the additive manufacturing community. [ABSTRACT FROM AUTHOR]

Selective laser sintering (SLS) is a well-established technology that is used for additive manufacturing. Significant efforts have been made to improve SLS by optimizing the powder deposition, laser beam parameters, and temperature settings. The purpose is to ensure homogeneous sintering and prevent geometric and appearance inaccuracies in the manufactured objects. We evaluated the differences in the surface roughness and grain size of curved objects manufactured by using upcoming SLS technology that features two CO laser sources. Our analysis was carried out on polyamide 11 (PA11), which is a sustainable biobased polymer that has been gaining popularity due to its high-performance properties: its low melting point, high viscosity, and excellent mechanical properties. By using a Taguchi experimental design and analysis of variance (ANOVA), we examined the influence on the surface roughness and grain size of the build setup, the presence of thin walls, and the position of the sample on the powder bed. We found significant differences in some surface roughness and grain size measurements when these parameters were changed. [ABSTRACT FROM AUTHOR]

In-situ co-axial meltpool monitoring has become a popular tool for digitising the laser powder bed fusion (L-PBF) process, providing baseline data for certification. Each layer produces an image where the pixel position represents the laser coordinates and the pixel intensity denotes the sensor response. The 3D image stacks represent the infrared emission during the manufacturing of the physical component. However, interpreting monitoring data remains a challenge. To address this issue, this study evaluates the performance of a near-infrared photodiode in detecting typical geometrical features such as porosity and overhanging structures ranging from the micro-to-meso scale. Monitoring data is highly sensitive to heat accumulation around overhanging structures and can quantify dross formation based on hotspots. Cold spots, which represent a lack of fusion porosity at scan track intersections, can indicate a probability of defect formation. However, the sensitivity and predictive value of monitoring data for porosity are low due to the healing of defects in subsequent layers. Local process variables, such as the scan strategy and part orientation, significantly influence dross and hot spot formation. This study shows the potential of NIR photodiodes in deriving metrics for in-line certification of L-PBF components, leading to improved process control and quality assurance. [ABSTRACT FROM AUTHOR]

Objective: 3D-printed models hold great potential for temporal bone surgical training as a supplement to cadaveric dissection. Nevertheless, critical knowledge on manufacturing remains scattered, and little is known about whether use of these models improves surgical performance. This systematic review aims to explore (1) methods used for manufacturing and (2) how educational evidence supports using 3D-printed temporal bone models. Data Sources: PubMed, Embase, the Cochrane Library, and Web of Science. Review Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, relevant studies were identified and data on manufacturing and validation and/or training extracted by 2 reviewers. Quality assessment was performed using the Medical Education Research Study Quality Instrument tool; educational outcomes were determined according to Kirkpatrick's model. Results: The search yielded 595 studies; 36 studies were found eligible and included for analysis. The described 3D-printed models were based on computed tomography scans from patients or cadavers. Processing included manual segmentation of key structures such as the facial nerve; postprocessing, for example, consisted of removal of print material inside the model. Overall, educational quality was low, and most studies evaluated their models using only expert and/or trainee opinion (ie, Kirkpatrick level 1). Most studies reported positive attitudes toward the models and their potential for training. Conclusion: Manufacturing and use of 3D-printed temporal bones for surgical training are widely reported in the literature. However, evidence to support their use and knowledge about both manufacturing and the effects on subsequent surgical performance are currently lacking. Therefore, stronger educational evidence and manufacturing knowhow are needed for widespread implementation of 3D-printed temporal bones in surgical curricula. [ABSTRACT FROM AUTHOR]

This paper presents a process chain of powder injection moulding with sacrificial moulds. The mould is fabricated by vat polymerization based additive manufacturing, which enables production of complex metal parts. A special metal feedstock is developed, which allows near-zero injection pressure. The part is ejected together with the polymer mould. After the mould is dissolved, the released part is debinded and sintered. Micro features are printed on the mould surfaces, and the quality of the part is correlated with the replicated features in each process step. In this way the micro features are used as quality indicator, namely, a fingerprint. [ABSTRACT FROM AUTHOR]

This paper introduces two new deposition-strategies for five degrees of freedom (5DOF) and 6DOF extrusion-based additive manufacturing (AM), called the tool path projection- and parent-child-approach, respectively. The tool path projection method can be automated, and allows for the generation of concentric shells layers, which remedy geometrical deviations (known as the stair-case effect) that are typically seen in 3DOF AM processes that potentially require secondary post treatment by machining or grinding of the final part. In the parent-child approach, the designer specifies the manufacturing direction for each distinct feature, thereby helping to remove the need for support material, as well as enabling new features to be dynamically added to the part. [ABSTRACT FROM AUTHOR]

There is a growing interest for integrating additive manufacturing (AM) technology in different manufacturing processes such as injection moulding (IM) due to the possibility of achieving shorter manufacturing times and increased cost effectiveness. This paper evaluates IM inserts fabricated by the AM vat photopolymerisation method. The inserts are directly manufactured with a photopolymer material, integrated on an injection moulding tool and subsequently used for IM. Therefore, particular attention has to be paid in order to develop the soft tooling process chain and the IM experimental procedure as detailed in this study. Different combinations of IM parameters are investigated in this work in order to determine the influence of the various process settings on the inserts' performance (lifetime, crack propagation, consistency of the mould surface features). The mould inserts were analysed by three-dimensional optical metrology and evaluated with regard to the different surface features that were affected by the IM process. A three-dimensional thermo-mechanical with phase change model for the analysis of the effects of the IM process on the additive manufactured tools was accomplished in the FE software COMSOL Multiphysics. The potential causes for the insert failure are identified both by means of the IM experiments and the numerical model. The developed model could also predict the thermally induced deformations produced in the mould and identify where this phenomenon would eventually lead to defects in the shape of the parts. The influence of three different temperatures of the insert at 25 °C, 50 °C and 100 °C on the failure of the insert was investigated. Also a detailed discussion about the solidification and temperature changes is given. [ABSTRACT FROM AUTHOR]

Additive manufacturing technologies are these years entering the market of functional final parts. Initial research has been performed targeting the integration of fibers into additive manufactured plastic composites. Major advantages, among others, are for example increased tensile strength and Young's modulus. Key challenges in the field, as of now, are proper fiber placement, fiber seizing, an increased knowledge in the used materials and how they are applied into engineering solutions through proper control of the additive manufacturing process. The aim of this research is the improved understanding of fiber-reinforcement in additive manufacturing in terms of production and application. Vat polymerization and material extrusion techniques for composite additive manufacturing were investigated with respect of increasing adhesion between the matrix material and the fibers. Process optimization was performed in order to avoid matrix cracks and delamination. [ABSTRACT FROM AUTHOR]

A delta-type parallel kinematics system for Additive Manufacturing has been created, which through a probing system can recognise its geometrical deviations from nominal and compensate for these in the driving inverse kinematic model of the machine. Novelty is that this model is derived from a virtual machine of the kinematics system, built on principles from geometrical metrology. Relevant mathematically non-trivial deviations to the ideal machine are identified and decomposed into elemental deviations. From these deviations, a routine is added to a physical machine tool, which allows it to recognise its own geometry by probing the vertical offset from tool point to the machine table, at positions in the horizontal plane. After automatic calibration the positioning error of the machine tool was reduced from an initial error after its assembly of ±170 µm to a calibrated error of ±3 µm. Excelling by speed, the calibration was executed in less than 3 min. [ABSTRACT FROM PUBLISHER]

To investigate the impact of 3D-printed temporal bone models with two different material transparencies on trainees' mastoidectomy performance. Eleven ORL residents performed two anatomical mastoidectomies with posterior tympanotomy on two 3D-printed models with different transparency and VR simulation training. Participants where divided into two groups based on their experience. Within each group participants were randomized to start with the model printed in a completely opaque material or in a material featuring some degree of transparency. After drilling on 3D-printed models, the participants performed two similar mastoidectomies on human cadavers: one on the left side of one cadaver and one on the right side of another cadaver. After drilling 3D-printed models and cadavers, the final-product performances were evaluated by two experienced raters using the 26-item modified Welling Scale. Participants also evaluated the models using a questionnaire. Overall, the participants performed 25 % better on the 3D-printed models featuring transparency compared to the opaque models (18.6 points vs 14.9 points, mean difference = 3.7, 95 % CI 2.0–5.3, P < 0.001)). This difference in performance was independent of which material the participants had drilled first. In addition, the residents also subjectively rated the transparent model to be closer to cadaver dissection. The experienced group starting with the 3D-printed models scored 21.5 points (95 % CI 20.0–23.1), while the group starting with VR simulation training score 18.4 points (95 % CI 16.6–20.3). We propose that material used for 3D-printing temporal bone models should feature some degree of transparency, like natural bone, for trainees to learn and exploit key visual cues during drilling. [ABSTRACT FROM AUTHOR]

• Fabrication of the components with injection molding (IM), soft tooling method. • Influence of thermal ageing on the fracture and lifetime behavior of polymer printed inserts. • The surface roughness of the unaged, aged before IM and aged after IM experiments were evaluated. • Measurement and comparison of the IM unaged and aged parts components. • Thermal ageing leads to crack formations in different areas in the mold inserts. Due to the significant technical benefits of additive manufacturing (AM), its application has grown considerably in recent years. In this respect, the integration of AM in the injection molding (IM) process chain for tooling purposes is an ongoing research topic. In the current study, the design, fabrication and use of a tool inserts for injection molding process fabricated by a vat photopolymerisation technique. Since molds during the injection molding process are subjected to cyclic thermal variation, accelerated thermal ageing was applied on the AM mold inserts to emulate the effect of continuous production on the tool lifetime. The additively manufactured mold inserts were exposed to thermal cycling loading in the range between room temperature up to 100 °C, and then, they were used in the actual injection molding process. According to the obtained results, effects of thermal ageing on behavior of the mold inserts are demonstrated. Moreover, fractographic analysis is performed on the fractured surfaces to determine crack initiation and propagation on the mold inserts. The current study provides insight about ageing and fracture of IM mold inserts produced by vat photopolymerisation , and these results can be used for the development of computational models, future material design and load-carrying capabilities of additively manufactured mold inserts to expand the use of AM for tooling purposes. [ABSTRACT FROM AUTHOR]

This work presents an Additive Manufacturing (AM) based method for production of components with micro-structured surfaces. Vat photopolymerization was used for the experiments by an AM custom-build machine at the Technical University of Denmark (DTU). Components with micro holes were printed in different sizes and the uniformity of them analyzed. Subsequently, in order to assess the functionality of the surface, the water droplet contact angle was measured to evaluate the wettability of the different components with micro holes. It was found that it was possible to fabricate the components with micro holes using precision AM process. The printed substrate exhibited hydrophobicity as a hydrophilic material (intrinsic contact angle of 65°). A hydrophobic surface was achieved with the printed features exhibiting a maximum contact angle of 113°. Additionally, the volume of fluid (VOF) method was employed to predict the surface contact angle. The predicted results were validated by comparison against the experiments. The average value from experiments was predicted by the model. However, it was noted that the cross-sectional height profile of the structures and the surface roughness of the printed samples, were not precisely replicated as designed, which slightly affects the prediction results, though, similar prediction trend was observed. Unlabelled Image • Direct fabrication of the components with micro structured surfaces by digital light processing method. • Digital Light Processing method was pushed to its limit for fabrication of the components with micro holes. • Measurement of the components with micro holes present uniformity of the print in different areas of the structure. • The printed substrate realized hydrophobicity on the hydrophilic materials (intrinsic contact angle of 65°). • 3D dynamic impact behavior simulation for contact angle prediction was used to estimate wettability of the surface. [ABSTRACT FROM AUTHOR]