Key Engineering Materials Vol. 1058

Abstract: In this present work, a newly emerging manufacturing process, namely metal additive manufacturing, is discussed in detail. The review work considers articles that describe the impact of ultrasonic vibration assistance on the laser-based Directed Energy Deposition (LP-DED) process, a promising approach in metal additive manufacturing. The incorporation of high-frequency ultrasonic vibrations during deposition enhances melt pool dynamics, promotes refined grain structures, and significantly reduces the formation of porosity and residual stress. Ultrasonic-assisted DED contributes to improved interlayer bonding, uniform particle dispersion, and enhanced mechanical properties of the printed part. Results indicate that this hybrid approach can optimise deposition quality and mechanical performance, making it suitable for critical applications across aerospace, biomedical, and energy sectors. The findings highlight ultrasonic assistance as a valuable tool for overcoming key challenges in conventional DED processes.

Abstract: Wire arc additive manufacturing (WAAM) with the Gas Metal Arc Welding (GMAW) method has a high deposit rate. It is more efficient and capable of producing small and medium-sized components economically. In addition to parameter selection, the WAAM process is also influenced by the choice of the filler wire types to determine the process stability, quality of the results, and desired dimensions. Filler wire selection in the WAAM process is important because it uses aluminum alloys commonly used in ER4043 and ER5356 fillers. This research method employs experiments using ER4043 and ER5356 filler wires and AA6061 substrate to determine suitable parameters for a stable WAAM process. It then measures bead dimensions, surface roughness, and tests for damage-free operation using dye penetrant. The experimental results obtained using the ER4043 wire with a diameter of 1 mm, a current of 80 A, and a voltage of 14 V were unstable. In contrast, using the ER5356 filler, the stable experimental process. The arc length affects the bead geometry. Some of the impacts that occur due to the arc length are defects such as porosity, protrusions, and collapse areas in the final bead area, as well as the absence of fusion defects on the bead edges.

Abstract: Recent developments in 3D-printed prosthetic and bionic hands are reviewed in this study with an emphasis on anthropomorphic design that attempts to mimic the structure, dexterity and mobility of a human hand. Because people with limb loss face obstacles that affect their everyday functioning and confidence, the development of accessible, functional and aesthetically pleasing bionic hands is an important goal in biomedical research. Researchers have found that Polylactic Acid (PLA) and Thermoplastic Polyurethane (TPU) blended composites are the most popular materials in a number of studies. As PLA has mechanical limits despite being a biodegradable material derived from renewable resources, it is frequently mixed with TPU for more flexibility and adaptability while maintaining comfort and light weight. Additionally, the experimental results in this review hint that tiny servos may produce enough mechanical output for gripping operations without overheating or using too much energy. The resulting performance, strength and durability of bionic hands are strongly affected by the material choice and design customization, which also opens the door for further improvements in this area.

Abstract: Secondary machining of Carbon Fibre-Reinforced Polymer (CFRP) is crucial for achieving precise dimensions and high-quality finishes in manufacturing. However, CFRP's anisotropic and heterogeneous properties present challenges, including delamination, high thrust forces, and excessive tool wear, which can compromise the final products' mechanical integrity and durability. Optimizing machining processes to minimize these issues and enhance tool life is a significant area of research. This study focuses on CFRP drilling operations, investigating the effects of varying feed rates and spindle speeds on critical machining parameters such as delamination factors. Experiments utilize CFRP made of TRH50 fibre and NCT 301 resin, with a solid carbide-tip and diamond-coated tool featuring a stainless-steel body. The research aims to provide insights into the interactions between machining parameters and CFRP properties, contributing to the development of optimized machining strategies for improved performance and product quality. Preliminary findings revealed visible exit and entry delamination during the drilling operation.

Abstract: Wire Electrical Discharge Machining (WEDM) is a non-traditional machining method for fabricating hard and conductive materials. This study investigates the influence of four key process parameters such as pulse on-time, pulse off-time, wire feed rate, and current on machining performance using stainless steel 316. The effect of these process parameters is studied in terms of volumetric material removal rate (VMRR), surface roughness (Ra), and side gap. Experiments were conducted using a CNC WEDM setup, and the results were analyzed using Response Surface Methodology (RSM) via Minitab 17 to develop regression models. The results show that wire feed and the current predominantly influence VMRR, pulse on-time has the strongest effect on Ra, while pulse off-time and the current are most significant for controlling side gap. The study offers a data-driven reference for optimizing WEDM process while contributing to improved machining performance, energy efficiency, and surface integrity to machine hard materials.

Abstract: In deep-hole drilling using long drills (L/D >= 40), chip evacuation becomes poor, and step-feed drilling is therefore employed, resulting in reduced machining efficiency. Although the use of high-pressure coolant (HPC) machining technology is expected to improve chip evacuation as well as reduce tool damage, few studies have investigated the effects of applying a high-pressure coolant to deep-hole drilling with long drills, either domestically or internationally. Therefore, this study aimed to propose and experimentally demonstrate the combined use of a high-pressure coolant during drilling in order to achieve high-efficiency and high-precision deep-hole machining (L/D = 40) using a 5-mm-diameter drill. The results that (1) at a cutting speed of 60 [m/min], the flank wear on both cutting edges was significantly greater at a coolant pressure of 0.2 [MPa] than at 20 [MPa], (2) although the axial hole deviation varied with the number of holes, it was smaller at a cutting speed of 90 [m/min] than that at 80 [m/min], and so on, were obtained.

Abstract: Ripple marks are typical surface defects in aluminum alloy strip cast using a twin-roll caster. Ripple marks occur whether or not a nozzle is used, but become remarkably pronounced when a nozzle is used and the melt head increases. The ripple marks on strip cast using a vertical-type high-speed twin-roll caster were different from those formed when using a conventional horizontal-type twin-roll caster. The formation of ripple marks was influenced by Si content, indicating that ripple marks are affected by latent heat and viscosity in the semi-solid state. The occurrence of ripple marks was predicted and they were classified into three types based on Si content. Additionally, the shape of the nozzle tip, which might improve the occurrence of these defects, was discussed.

Abstract: Disulphide-containing polymers have recently been recognized as an invaluable material in delivering chemotherapeutic drug. Disulphide-based polymers are considered potential candidates because of their sensitivity to redox conditions and their stability in the challenging environment of the upper GI tract. In this study, three polymers have been successfully synthesised via oxidation of citric acid derivative-thiolated monomer and dithiol monomers. Three disulphide-based polymers were successfully synthesized and used to encapsulate docetaxel and salinomycin, demonstrating their applicability for colon-targeted drug delivery.

Abstract: In this experiment, nano-sucralfate for gastric mucosa protection was prepared by the pyridine method using sucrose, sulfuric acid and aluminum powder as raw materials. The product was characterized by Fourier transform infrared spectrometer (FTIR), thermogravimetric analyzer (TGA) and its surface micro-morphology was observed by scanning electron microscope (SEM).. Infrared spectroscopy and thermogravimetric analysis explored the physical and chemical properties of sucralfate, providing specific data support for its practical application. SEM images showed that sucralfate particles had a porous flower-like structure with high porosity. In addition, the synthesized product has high purity and good thermal stability, which play an important role in improving its protective effect on gastric mucosa.

Abstract: This study develops electrospun wound dressings using 8% PCL with 0–6% aloe vera (AV). SEM reveals uniform fibrous structures with thinner fibers (0.318–0.882 μm) as AV increases. FTIR confirms the presence of both components and absence of solvent residues. Antibacterial tests against E. coli and S. aureus reveal inhibition zones of 9–11 mm, with 6% AV showing the most substantial effect.