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Due to their low cost, lightweight, antifouling and anticorrosion properties, polymer heat exchangers (PHXs) are replacing metal heat exchangers in a variety of applications. Nowadays, 3D printing technology is gaining increasing attention to fabricate these PHXs. This study employs Fused Deposition Modeling (FDM), a popular 3D printing technique, to construct PHXs from ABS material (i.e., Acrylonitrile Butadiene Styrene) and investigates some of the important parameter effects on their heat transfer performance under varied operating conditions. Experiments were performed for the shell side flow rates varying from 0.6 to 3 L/min and tube side flow rates varying from 1.2 to 3.6 L/min. The overall heat transfer coefficient (U) ranged from 66 to 121 W/m2 K in these printed PHXs, thereby showing the effect of printing and operating conditions. The results showed that the printing temperature (PT) and tube wall thickness (WT) had a significant influence on the thermal performance of PHXs while the printing speed (PS) demonstrated a trivial effect. Apart from enhancing the thermal performance, higher printing temperature also resulted in lowering the dimensional variations. The roughness analysis of the tubes revealed that the PHXs with smooth surfaces interestingly had better heat transfer performance than tubes with rougher surfaces. Further, such smooth surfaces were realized with a high printing temperature. These findings conclude that higher roughness does not necessarily improve the thermal performance of layered PHXs, contrary to continuous structure HXs. Also, high printing temperature, small wall thickness, and low printing speed are conducive conditions to produce printed PHXs with greater thermal performance, and reduced roughness and dimensional variations. This study can act as a guideline for printing precise and high-performance PHXs. [ABSTRACT FROM AUTHOR]

Typical additive manufacturing (AM) processes for producing metal and ceramic parts are highly energy-consuming and expensive to install and maintain. On the other hand, material extrusion AM (MEAM) technologies are conventionally used to produce polymeric parts but only marginally to process metallic materials. A feasible alternative is to process polymeric filaments loaded with metal particles. Debinding and sintering processes are then required to join the metal particles and obtain the final parts. In recent years, highly filled metal filaments consisting of a polymer loaded with a high concentration of metal powder have been commercialized for this purpose. In this study, the printability of a commercial CuSn12 filament was investigated by evaluating the influence of the process parameters on the density, shrinkage, porosity, and mechanical properties of the additively manufactured samples using a low-cost desktop 3D printer. Parameters such as the flow rate and ironing had the greatest influence on the density of the green samples. The correct selection of these parameters may reduce shrinkage after sintering. Furthermore, the obtained bronze had a notable ultimate tensile strength (mean value of 107 MPa), high stiffness (E values range from 38 to 50 GPa), and a greater elongation at break (mean value of 13%) than that of cast bronze of the same CuSn12 type. In this case, the extrusion pattern and ironing had the most significant influence on the final mechanical performance. The study provides insights into the use of highly filled bronze filaments combined with MEAM to produce functional parts for engineering applications. [ABSTRACT FROM AUTHOR]

By the term, lattice structures are intended topologically ordered open-celled structures consisting of one or more repeating unit cells. Technological development and especially the growth of the additive manufacturing (AM) industry allows innovative structural design, including complex lattice structure. Selective laser melting (SLM) is an AM process that enables the manufacture of space filling structures. This work investigated the influence of the most important process parameter settings on lattices printability, focusing on the geometrical accuracy, the quantity of powders adhered to the main frame (satellites) and their compression behaviour. The process parameters such as the laser power, scan speed and layer height affect vigorously the design, quality and mechanical properties of the part. The aim of the paper is to evaluate how different parameter combinations affect the cellular structures' printing. Twenty-four lattice structures with cubic and rhombic dodecahedron unit cells made of stainless steel 17-4PH (AISI-630) were printed using different combinations of SLM process parameters. Each structure was analysed considering its geometrical, topological and mechanical properties. Finally, the best parameter combination was evaluated comparing results achieved. Although this work investigated the 17-4PH stainless steel, physical principles related to the printing process described are generally true for the SLM process. Therefore, the adopted approach could still be suitable also for all the other materials commonly used with this AM technology. [ABSTRACT FROM AUTHOR]

Low-cost metal additive manufacturing remains difficult but would be of great practical value. To prepare slurry distributed evenly and stably, the present study thoroughlymixed metal powder, as a basematerial, with corresponding monomers, crosslinking agents, dispersant, initiator, and catalysts. A complex three-dimensional structure of iron powder slurry was built using a pneumatic injection additive manufacturing system. The effects of the injection pressure, platform speed, and nozzle diameter on the width of printed lines were studied. The stability of the width of a single printed line was investigated. It was found that the line width increases with an increase in the injection pressure or nozzle diameter and decreases with an increase in the moving speed of the platform. A reasonable drying, debinding, and sintering schedule was established, and the microstructures of dried, debinding, and sintered parts were analyzed. The sintered parts were denser than dried and debinding parts. The pneumatic injection additive manufacturing technology adopted in this study has the advantages of lowmanufacturing costs and a wide range of printing materials, and is applicable in the additive manufacturing of iron powder and a variety of other metal powders, thus widening the range of materials used in additive manufacturing. [ABSTRACT FROM AUTHOR]