Machining of Ti-6Al-4V biomedical alloy by WEDM: investigation and optimization of MRR and Rz using grey-harmony search

Purpose The purpose of this paper is to investigate the optimized setting of wire-cut electrical discharge machining (WEDM) parameters at which material removal rate (MRR) and mean roughness depth (Rz) set a compromise. The problem in the processing of Ti-6Al-4V by conventional processes is a high strength, high hardness, high tool wear. Due to which WEDM is adopted to machine Ti-6Al-4V biomedical alloy. Ti-6Al-4V alloy has a number of applications in the engineering and medical industries due to its high strength biocompatibility. Design/methodology/approach The effect of control factors (i.e. pulse on-time: Pon; pulse off-time: Poff; servo voltage: SV) on the MRR and Rz is investigated in the present research. The planning of experiments is done using a Taguchi-based L9 orthogonal array. The percentage influence of each factor on responses is also evaluated. The multi-objective optimization is done using the grey approach initially. After that, the results were also calculated using harmony search (HS). Therefore, a hybrid approach of grey and HS is used to find the optimized values of MRR and Rz. Findings The maximum value of grade calculated by grey-HS is 0.7879, while in the case of the experimental run the maximum value of grey grade is 0.7239. The optimized setting after improvisation at this grade value is Pon: 130 µs; Poff: 45 µs and SV: 70 V for MRR and Rz collectively. The validation of the suggested setting is completed by experimentation. The values of MRR and Rz are coming out to be 6.4 mm3/min and 13.84 µm, which represents improvised results after the implementation of the HS algorithm. Originality/value The integration of the grey approach with the HS principle in the manufacturing domain is yet to be explored. Therefore, in the present research hybrid approach of grey-HS is implemented in the manufacturing domain having applications in medical industries.

Biodegradation, Antibacterial Performance, and Cytocompatibility of a Novel ZK30-Cu-Mn Biomedical Alloy Produced by Selective Laser Melting

An antibacterial biomedical Mg alloy was designed to have a low biodegradation rate. ZK30-0.2Cu-xMn (x = 0, 0.4, 0.8, 1.2, and 1.6 wt.%) was produced by selective laser melting (SLM). Alloying with Mn had a significant influence on the grain size, hardness, and biodegradation rate. Increasing Mg content to 0.8 wt% decreased the biodegradation rate, attributed to the decreased grain size and the relatively protective manganese surface oxide layer. Higher Mn contents increased the biodegradation rate attributed to the presence of the Mn-rich particles. ZK30-0.2Cu-0.8Mn exhibited the lowest biodegradation rate, strong antibacterial performance and good cytocompatibility.