Search Results (3)

One of the most popular alloys for biomedical applications is TiAl6V4. Even though TiAl6V4 is widely used, it faces several challenges. Firstly, TiAl6V4 is prone to stress shielding caused by the difference in Young’s moduli of the alloy (110 GPa) and human bones (20–30 GPa). Secondly, there is the presence of cytotoxic elements, aluminum and vanadium. Researchers have proposed Ti-35Nb-7Zr-5Ta (TNZT) alloy to overcome these disadvantages, an excellent substitute for natural human bones. This alloy offers a lower elastic modulus (up to 81 GPa), much closer to human bones than TiAl6V4 alloy. Also, TNZT alloy contains no cytotoxic elements and has excellent biocompatibility and high corrosion resistance. Given the positive outcomes on powder-mixed micro electro-discharge machining (PM-μ-EDM) of Ti alloy using hydroxyapatite (HA) powder, we studied the machinability of TNZT alloy using HA powder mixed-μ-EDM by changing the HA powder concentration (0, 5, and 10 g/L), gap voltage (90, 100, and 110 V), and capacitance (10, 100, and 400 nF) according to the Taguchi L9 method. Machining performance metrics such as material removal rate (MRR), overcut, and circularity were examined using a tungsten carbide tool of 237 µm diameter. The results showed an overcut of 10.33 µm, circularity of 8.47 µm, and MRR of 6030.89 µm³/s for the lowest energy setup. Full article

The powder-mixed electro-discharge machining (PM-EDM) technique has shown its advantages in forming surfaces and depositing elements on the machined surface. Moreover, using hydroxyapatite (HA) powder in PM-EDM enhances the biocompatibility of the implant’s surfaces. Ti-6Al-4V alloy has tremendous advantages in biocompatibility over other metallic biomaterials in bone replacement surgeries. However, the increasing demand for orthopedical implants is leading to a more significant number of implant surgeries, increasing the number of patients with failed implants. A significant portion of implant failures are due to bacterial inflammation. Despite that, there is a lack of current research investigating the antibacterial properties of Ti-6Al-4V alloys. This paper focuses on studying the performance of HA PMEDM on Ti-6Al-4V alloy and its effects on antibacterial properties. By changing the capacitance (1 nF, 10 nF and 100 nF), gap voltage (90 V, 100 V and 110 V) and HA powder concentration (0 g/L, 5 g/L and 10 g/L), machining performance metrics such as material removal rate (MRR), overcut, crater size and hardness were examined through the HA PM micro-EDM (PM-μ-EDM) technique. Furthermore, the surface roughness, contact angle, and antibacterial properties of HA PM micro-wire EDM (PM-μ-WEDM)-treated surfaces were evaluated. The antibacterial tests were conducted for Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Bacillus subtilis bacteria. The key results showed a correlation between the discharge energy and powder concentration with the antibacterial properties of the modified surfaces. The modified surfaces exhibited reduced biofilm formation under low discharge energy and a 0 g/L powder concentration, resulting in a 0.273 μm roughness. This pattern persisted with high discharge energy and a 10 g/L powder concentration, where the roughness measured 1.832 μm. Therefore, it is possible to optimize the antibacterial properties of the surface through its roughness. Full article

Micro-electro-discharge machining (μEDM) plays a significant role in miniaturization. Complex electrode manufacturing and a high wear ratio are bottlenecks for μEDM and seriously restrict the manufacturing of microcomponents. To solve the electrode problems in traditional EDM, a µEDM method using liquid metal as the machining electrode was developed. Briefly, a liquid-metal tip was suspended at the end of a capillary nozzle and used as the discharge electrode for sparking the workpiece and removing workpiece material. During discharge, the liquid electrode was continuously supplied to the nozzle to eliminate the effects of liquid consumption on the erosion process. The forming process of a liquid-metal electrode tip and the influence of an applied external pressure and electric field on the electrode shape were theoretically analyzed. The effects of external pressure and electric field on the material removal rate (MRR), liquid-metal consumption rate (LMCR), and groove width were experimentally analyzed. Simulation results showed that the external pressure and electric field had a large influence on the electrode shape. Experimental results showed that the geometry and shape of the liquid-metal electrode could be controlled and constrained; furthermore, liquid consumption could be well compensated, which was very suitable for µEDM. Full article