Advances in Science and Technology Vol. 180

Abstract: Fused deposition modelling (FDM) is a widely adopted additive manufacturing (AM) technique known for its accessibility and versatility. However, FDM parts exhibit anisotropy and layer-dependent variability in mechanical properties, complicating material behavior prediction. In this study, the effect of the following key FDM parameters, build orientation, printer setup, and layer deposition time on the mechanical performance of PLA specimens, will be examined. Standard ISO 527 tensile tests were performed, and the values of Young’s modulus, ultimate tensile strength, and interlayer bonding strength (IBS) were obtained. The analysis has shown that increased layer laying times result in increased cooling between layers, which in turn reduces IBS and interlayer adhesion. A finite element (FEA) numerical model that accurately represents the anisotropic and nonlinear response of printed parts has been developed based on microstructural analysis. The findings are expected to enable predictive modelling and optimization of FDM process parameters and provide practical guidelines for improved interlayer bonding and overall print reliability.

Abstract: In this study, 17-4PH precipitation-hardening stainless steel specimens were fabricated via FDM metal 3D printing followed by debinding and sintering. The effects of printing pattern (cubic, linear, and grid) and infill density (90% and 100%) on mechanical performance and porosity were systematically investigated. Experimental results indicate that printing parameters have a significant influence on mechanical performance, with different properties exhibiting varying sensitivities to process conditions. Hardness is strongly affected by printing pattern and infill density; the cubic lattice path combined with 90% infill density achieved the highest hardness of 52.52 HRB, suggesting enhanced densification and internal structural uniformity after sintering. Tensile test results show that the grid printing pattern with 90% infill density provides superior mechanical performance, yielding a maximum tensile load of 1895.33 kgf and an elongation of 6.07 mm, indicating improved ductility. Yield strength and Poisson’s ratio analysis further reveal a maximum yield strength of 228.825 kgf and a Poisson’s ratio of 0.697 under the same conditions. Porosity analysis demonstrates that the linear printing pattern at 100% infill density produces the lowest porosity of 30.80%. Although higher infill density effectively reduces porosity, the overall mechanical behavior of FDM-printed and sintered 17-4PH specimens exhibits characteristics typical of brittle materials. These findings provide valuable insights for optimizing FDM process parameters in metal additive manufacturing.

Abstract: This study investigates the synthesis of low-melting-point calcium aluminate fluxes via the electrofusion of recycled aluminum dross and CaO, aiming to develop a sustainable alternative to CaF₂ in secondary steel refining. Seven flux formulations with a target CaO/Al₂O₃ ratio of 0.92 and varying additions of B₂O₃ (0–5 wt.%) and MgO (0–3 wt.%) were characterized using XRD and DTA. The results indicate that the synergistic effect of B₂O₃ and MgO promotes the formation of the C₁₂A₇ phase, effectively lowering the melting point by up to 167°C compared to additive-free formulations. When integrated into CaO/Al₂O₃-based desulfurizers, the optimal flux (3 wt.% B₂O₃ and 3 wt.% MgO) demonstrated superior fluxing kinetics and achieved a desulfurization efficiency of 52–55% within 20 minutes, which is highly comparable to the performance of conventional 10 wt.% CaF₂-bearing agents (57%). This research provides a dual solution for high-value aluminum dross recycling and the development of eco-friendly, fluoride-free steel refining agents.

Abstract: A 0.035mm thickness copper foil stacked on adhesives was cut off using a WC wedge keen knife when changing the apex angle of the knife and the cutting velocity. When changing the velocity, the sinking state and the detaching of adhesives affected the bending and wedging state of the copper foil, while the apex angle of the knife affected geometrically and plastically the bending angle and the cutting line force in the cutting process. The residual warpage was affected by the cutting velocity.

Abstract: Upper Backer Press is one of the key production processes in piano manufacturing at PT. XYZ Indonesia. In the current configuration, the pressing process uses pneumatic pressure that acts directly on the upper surface of the sideboard. Surface defects, known as “uki” were observed on the sideboard after pressing due to an uneven distribution of contact pressure. To address the problem, a modified mechanical jig has been proposed, and a finite element simulation has been conducted to predict the contact distribution for each jig configuration. The results indicate that the optimized design of the modified jig distributes contact pressure uniformly. The modified design reduces defects and improves the quality of the piano sideboard.

Abstract: Bending copper tubing is a common operation in building mechanical installations, particularly in heating, ventilation, and air-conditioning (HVAC) and refrigeration systems, where accurate pipe alignment is required to ensure proper system performance. Conventional manual bending methods are widely used in field applications; however, they often require significant physical effort and may produce inconsistent bending angles, leading to installation errors, material damage, and reduced work efficiency. To address these limitations, a motorized copper-tube bending system was developed to improve bending accuracy, reduce manual workload, and enhance productivity during mechanical installation work. This study evaluates the performance of the developed motorized bending system in comparison with the conventional manual bending method. Experimental testing was conducted using standard copper tubes commonly used in building mechanical installations. The evaluation focused on bending angle accuracy, time efficiency, and operational consistency. Multiple trials were performed for both manual and motorized bending, and the results were analyzed using statistical methods to determine the significance of the observed differences. The results showed that the motorized bending system provided more consistent bending angles and reduced the required bending time compared to manual operation. The motorized device also minimized physical effort and improved repeatability during successive bending tasks. Statistical analysis confirmed that the motorized bending system's performance is significantly better in terms of accuracy and efficiency under the tested conditions. The findings of this study indicate that the developed motorized copper-tube bending system can be effectively used in building mechanical installations to improve work quality and productivity. However, the study is limited to a single tube size and short-term testing conditions; further evaluation across different tube diameters and long-term operation is recommended for future research.

Abstract: Aluminum melting furnaces in automotive wheel manufacturing consume substantial amounts of energy, contributing significantly to the overall carbon footprint. This study introduces a novel AI-based optimization framework that dynamically controls furnace operations, leveraging real-time process data to reduce energy consumption without compromising material quality. Experimental deployment in a production environment demonstrated energy savings of up to 18.5%, confirming the potential of AI in sustainable industrial metallurgy.

Abstract: Rifled barrels exhibit highly complex internal geometries and inevitably undergo wear and erosion damage under high-temperature, high-pressure, and severe friction conditions during service. Accurate and efficient finite element modeling of rifled barrels with different damage states is therefore essential for investigating projectile engraving behavior and interior ballistic performance. In this study, an automated parametric finite element modeling method for rifled barrels and damaged barrels is developed in a Python environment. By directly generating node and element data and exporting standard INP files, the proposed method eliminates geometric inaccuracies and topological inconsistencies. A graphical user interface is further developed and packaged as a standalone executable, allowing user-oriented visual parameter input and rapid generation of both intact and damaged barrel finite element models. Using the generated models, barrel-projectile coupled finite element simulations are conducted to investigate the effects of different barrel damage periods on projectile engraving resistance, in-bore motion, and muzzle exit characteristics. The results show that bore damage significantly degrades the centering capability of the rifling, resulting in increased projectile center-of-mass displacement and nutation angle during interior ballistics. The proposed parametric modeling framework provides an efficient and robust tool for interior ballistic analysis and damage sensitivity assessment of rifled barrels.

Abstract: Since the thermal expansion affects seriously the thermodynamic properties of the materials, a firm understanding and description of the thermal expansion phenomena are of primordial importance in any field of materials science. In the present study, an analytical model for the thermal expansion coefficient is developed based on a parametrized form of the interatomic potential and a modified Debye model for the distribution of atomic oscillations. In the model, it is hypothesized that the effect of anharmonicity can be incorporated through a variation of the Debye temperature. The deduced analytical expression indicates that the thermal expansion coefficient consists of a Debye-like component plus additional terms. The functional form of the derived expressions seems to grasp the gross trend of experimental observations. In view of this character, the derived analytical expression is promising, because it could be applied and extended to analyze the thermal expansion coefficient of different materials.

Abstract: Concrete, a widely used building material, faces challenges due to high demand, strain on resources, and environmental impact. As a result, the construction sector is shifting towards renewable resources and creative use of recycled materials. Construction and demolition waste, including concrete, wood, asphalt, and metals, contributes significantly to waste production. Using construction and demolition waste as aggregate in concrete production could be a potential solution to mitigate environmental impact and resource scarcity. This research aimed to provide an alternative approach for construction by experimenting with recycled coarse aggregates from concrete road pieces to determine high-performing mix proportion for concrete. The goal was to create a durable and cost-effective structure with comparable compressive strength, flexural strength, and water absorption to natural concrete. The study conducted tests on concrete cylinders and beams with different percentages (50%, 75%, and 100%) of recycled concrete road debris as coarse aggregate. The results demonstrated that mixtures with 50% and 75% of concrete road debris exhibited comparable strength and durability to conventional concrete. However, a mix with 100% concrete road debris showed a significant decrease in performance and was not recommended. This research underscored the possibility of utilizing recycled concrete road debris as a partial replacement for natural aggregates.