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This study aims to make foamed polylactic acid (PLA) structures with different densities by varying deposition temperatures using the material extrusion (MEX) additive manufacturing process.

The extrusion multiplier (EM) was calibrated for each deposition temperature to control foaming expansion. Material density was determined using extruded cubes with the optimal EM value for each deposition temperature. The influence of deposition temperature on the tensile, compression and flexure characteristics of the foamable filament was studied experimentally.

The foaming expansion ratio, the consistency of the raster width and the raster gap significantly affect the surface roughness of the printed samples. Regardless of the loading conditions, the maximum stiffness and yield strength were achieved at a deposition temperature of 200°C when the PLA specimens had no foam. When the maximum foaming occurred (220°C deposition temperature), the stiffness and yield strength of the PLA specimens were significantly reduced.

The obvious benefit of using foamed materials is that they are lighter and consume less material than bulky polymers. Injection or compression moulding is the most commonly used method for creating foamed products. However, these technologies require tooling to fabricate complicated parts, which may be costly and time-consuming. Conversely, the MEX process can produce extremely complex parts with less tooling expense, reduction in energy use and optimised material consumption.

This study investigates the possibility of stiff, lightweight structures with low fractions of interconnected porosity using foamable filament.

High silicon Si–Al alloys (50–70 wt% Si) have been developed by Osprey Metals Ltd for use in electronic packaging. They have the advantages of a coefficient of thermal expansion that can be tailored to match ceramics and electronic materials (6–11 ppm/K), low density (<2.8 g/cm³) high thermal conductivity (>100 W/m K). These alloys are also environmentally friendly and are easy to recycle.These Osprey alloys can be fabricated readily into electronic packages by conventional machining with tungsten‐carbide or polycrystalline diamond (PCD) tools and electro‐discharge machining (EDM). Generally more than one of these conventional machining operations is required in the fabrication process. A new and much faster method has been developed which has been used to produce complete electronic packages from plates of Si–Al alloys in a single machining step. In this novel method, known as thin‐shell electroforming (TSE), an accurate model of the package is produced directly from the drawing in wax using a 3D Systems ThermoJet Modeller. This model is mounted into a frame and it is then plated with a thin copper electroform. The wax model is then melted leaving the electroform attached to the frame. This is backfilled with solder and used as the EDM tool for machining the package from a plate of Si–Al alloy.

The purpose of this paper is to produce electric discharge machining (EDM) electrodes by using stereolithography (SLA) rapid prototyping technique and investigate the machining performance of these electrodes. In the experimental part of the study, the performance of solid copper and copper‐coated SLA (cc/SLA) electrodes are observed and compared.

The performance outputs such as material removal rate, machining depth, workpiece surface roughness and electrode front surface wear are used as metrics of comparison. The temperature measurements taken from the face of both solid copper and cc/SLA electrodes indicated that the heat build up during machining significantly accelerated the failure of cc/SLA electrodes.

The paper finds that circulating the cooling liquid inside the internal cooling channels formed with SLA technique, elongated the life of cc/SLA electrodes by dissipating the heat from the coating.

The Fluent Computational Fluid Dynamics (CFD) Software is used to numerically analyze various aspects of cooling of cc/SLA electrodes. The key findings of the study are presented in this paper.

Cu‐ZrB₂ shell electrodes were fabricated by composite electroforming to improve the spark‐resistance of the electrical discharge machining (EDM) electrodes made by rapid tooling.

Cu‐ZrB₂ shell electrodes were fabricated using composite electroforming, separating and backing. EDM performance evaluation of the Cu‐ZrB₂ shell electrodes is performed using tool steel as the cathode workpiece and the Cu‐ZrB₂ composite as the anode tool. The effects of ZrB₂ content on the electrode and workpiece removal rate, wear ratio of the electrode to workpiece, and surface quality of workpiece and electrode were studied.

Compared with the conventional electroformed copper tools, Cu‐ZrB₂ shell electrodes yield higher workpiece removal rate and lower tool wear ratio. Scanning electron microscopy (SEM) and electron microprobe analysis reveal that, due to the large difference between the melting point of ZrB₂ and copper, the heat generated by the sparks is conducted mainly through the copper matrix, reducing the erosion of ZrB₂ particles. The refractory ZrB₂ particles then act as barriers to the flowing and outburst of melted copper and enhance the resistance to erosion of the electrodes.

The use of Cu‐ZrB₂ shell electrodes improves the anti‐erosion properties of the EDM electrodes made by rapid tooling, especially in finish machining conditions. Such electrodes will not only reduce the failure of the EDM electrodes but also improve the machining precision due to the less dimension loss of the electrodes during machining.

The paper aims to explore the potential for using 3D printing technology as a more sustainable tool in various areas of the tourism and hospitality industry in Cyprus.

For the purpose of this study, qualitative research was conducted to explore the potential for 3D printing technology deployment in Cyprus and specifically in tourism and hospitality settings. Interviews were conducted with industry professionals and practitioners using a snowball sampling method.

The tourism and hospitality industry currently uses 3D printing technology mainly to assist with the restoration of cultural heritage, sites but there is significant potential to implement 3D printing more widely in support of other building work, souvenirs and food items.

The paper explores current applications and the wider potential for using 3D technology in building, restoration of cultural heritage, souvenirs and food-related printing that together could contribute to a more sustainable tourism and hospitality industry in Cyprus.

This study aims to analyze the effect of the different common post-processes on the geometrical and dimensional accuracy of selective laser melting (SLM) parts.

An artefact has been designed including cubic features formed by planar surfaces orientated according to the machine axes, covering all the X-Y area of the working space. The artefact has been analyzed both geometrically (flatness, parallelism) and dimensionally (sizes, distances) from coordinate measuring machine measurement results at three stages, namely, as-built, after sand-blasting and after stress-relieving heat treatment.

Results from the SLM machine used in this study lead to smaller parts than the nominal ones. This effect depends on the direction of the evaluated dimension of the parts, i.e. X, Y or Z direction and is differently affected by the sandblasting post-process (average erosion ratio of 68, 54 and 9 µm, respectively), being practically unaltered by the HT applied after.

This paper shows the influence, from a geometric and dimensional point of view, of two of the most common post-processes used after producing SLM parts, such as sand-blasting and stress-relieving heat treatment, that have not been considered in previous research.

The study aims to map the links between Industry 4.0 (I-4.0) technologies and circular economy (CE) for sustainable operations and their role to achieving the selected number of sustainable development goals (SDGs).

The study adopts a systematic literature review method to identify 76 primary studies that were published between January 2010 and December 2020. The authors synthesized the existing literature using Scopus database to investigate I-4.0 technologies and CE to select SDGs.

The findings of the study bridge the gap in the literature at the intersection between I-4.0 and sustainable operations in line with the regenerate, share, optimize, loop, virtualize and exchange (ReSOLVE) framework leading to CE practices. Further, the study also depicts the CE practices leading to the select SDGs (“SDG 6: Clean Water and Sanitation,” “SDG 7: Affordable and Clean Energy,” “SDG 9: Industry, Innovation and Infrastructure,” “SDG 12: Responsible Consumption and Production” and “SDG 13: Climate Action”). The study proposes a conceptual framework based on the linkages above, which can help organizations to realign their management practices, thereby achieving specific SDGs.

The originality of the study is substantiated by a unique I-4.0-sustainable operations-CE-SDGs (ISOCES) framework that integrates I-4.0 and CE for sustainable development. The framework is unique, as it is based on an in-depth and systematic review of the literature that maps the links between I-4.0, CE and sustainability.

The purpose of this paper is to propose and demonstrate a new additive manufacturing approach that breaks the layer-based point scanning limitations to increase fabrication speed, obtain better surface finish, achieve material flexibility and reduce equipment costs.

The freeform additive manufacturing approach conceptually views a 3D article as an assembly of freeform elements distributed spatially following a flexible 3D assembly structure, which conforms to the surface of the article and physically builds the article by sequentially forming the freeform elements by a vari-directional vari-dimensional capable material deposition mechanism. Vari-directional building along tangential directions of part surface gives surface smoothness. Vari-dimensional deposition maximizes material output to increase build rate wherever allowed and minimizes deposition sizes for resolution whenever needed.

Process steps based on geometric and data processing considerations were described. Dispensing and forming of basic vari-directional and vari-dimensional freeform elements and basic operations of joining them were developed using thermoplastics. Forming of 3D articles at build rates of 2-5 times the fused deposition modeling (FDM) rate was demonstrated and improvement over ten times was shown to be feasible. FDM compatible operations using 0.7 mm wire depositions from a variable exit-dispensing unit were demonstrated. Preliminary tests of a surface finishing process showed a result of 0.8-1.9 um Ra. Initial results of dispensing wax, tin alloy and steel were also shown.

This is the first time that both vari-directional and vari-dimensional material depositions are combined in a new freeform building method, which has potential impact on the FDM and other additive manufacturing methods.

This paper provides a quantitative and qualitative assessment of the effects of electroplating on polymer parts made by stereolithography (SL) and laser sintering. A series of test samples were coated with copper and nickel with varying thickness. Thicker coatings (120 μm) were reproduced with a repeatability that should not adversely affect the tolerances with which such parts may be produced given the tolerances of the initial rapid prototyping processes themselves. Thinner coatings (20 μm) resulted in a smother surface finish than thicker coatings for SL parts, however the converse was true for laser‐sintered parts. Composite theory was used to predict that thicker coating would lead to higher Young's modulus in parts and this was shown to be true in physical tests although the practical values were lower than the predicted values especially for thicker coatings. Physical tests also confirmed that thicker coatings increased UTS and impact energy but had a minimal effect on the ductility of parts.