Powder mixed-electro discharge machining (PM-EDM) is a new emerging trend in research on electro-thermal process that can simultaneously shape and deposit a coating on the surface of the workpiece. PM-EDM is a hybridized form of EDM in which metallic powders are amalgamated in dielectric liquid to enhance both the machined surface condition and machining performance. Migration of materials on the cutting surface occurs by melting and chemical reactions during the operation from both the electrodes and metallic powders. 316L stainless steel, Ti-based alloys, Co-Mo-Cr-based alloys, magnesium and magnesium-based alloys are commonly utilized in manufacturing biomedical devices. These biomaterials, however, release toxic particles due to corrosion, wear, tear, and tiredness of the joint replacements through repeated loads and relative movements. Surfaces of bio-implants made from these biomaterials are therefore protected using bioactive and biocompatible coating. Several methods of deposition are used for coating purposes which have both advantage and drawback. This study proposes that the PM-EDM coating enhances the biomaterials’ mechanical characteristics, surface morphology, and topography. Through reflecting critical and analytical concerns, this review focuses extensively on the current progress of the PM-EDM process. Moreover, following various research initiatives, this paper outlines the critical challenges and future research scopes.

Powder mixed-EDM is a newly emerging proposed manufacturing process which can simultaneously shape and coat the surface of conductive materials. Transformation of machined surface is occurred through melting and chemical reactions of the added powders, tools materials and dielectric fluid due to elevated temperature generation during the operation. Though the biomaterials such as titanium alloy, magnesium, 316 L SS and Co-Cr alloy attribute to higher mechanical strength, corrosion and wear resistance, and enough biocompatibility, these are limited to apply directly because of releasing the toxic elements and having inferior biological responses. Surfaces of bio-implants made from these biomaterials are therefore protected using bioactive and biocompatible coating. Hydroxyapatite is a bioceramic that possesses bone like element composition and excellent biocompatibility. The PM-EDM process with hydroxyapatite can enhance not only adhesion strength and roughness but also biocompatibility of the treated surface. It is proposed in this paper that carbide and oxide coating formation can improve the microhardness, bonding strength and roughness of surface of the substrates. This study comprehensively reports the current status of adhesion and surface coarseness of bio-ceramics based coating through PM-EDM process. A comparative critical analysis of employing bio-ceramic powder using various deposition techniques is presented in this review.

Together, 316L steel, magnesium-alloy, Ni-Ti, titanium-alloy, and cobalt-alloy are commonly employed biomaterials for biomedical applications due to their excellent mechanical characteristics and resistance to corrosion, even though at times they can be incompatible with the body. This is attributed to their poor biofunction, whereby they tend to release contaminants from their attenuated surfaces. Coating of the surface is therefore required to mitigate the release of contaminants. The coating of biomaterials can be achieved through either physical or chemical deposition techniques. However, a newly developed manufacturing process, known as powder mixed-electro discharge machining (PM-EDM), is enabling these biomaterials to be concurrently machined and coated. Thermoelectrical processes allow the migration and removal of the materials from the machined surface caused by melting and chemical reactions during the machining. Hydroxyapatite powder (HAp), yielding Ca, P, and O, is widely used to form biocompatible coatings. The HAp added-EDM process has been reported to significantly improve the coating properties, corrosion, and wear resistance, and biofunctions of biomaterials. This article extensively explores the current development of bio-coatings and the wear and corrosion characteristics of biomaterials through the HAp mixed-EDM process, including the importance of these for biomaterial performance. This review presents a comparative analysis of machined surface properties using the existing deposition methods and the EDM technique employing HAp. The dominance of the process factors over the performance is discussed thoroughly. This study also discusses challenges and areas for future research.

Fabrication of the 316 L steel with moderate surface roughness (SR) and thin recast layer (RLT) is very difficult using both the conventional and non-traditional machining processes. Due to the stochastic behavior of electro-discharge machining (EDM) process, the machining performances significantly rely on the system variables. This research work aims to investigate the influences of EDM method variables on the machining performances during the machining of 316 L steel. Another goal is to minimize the performances by applying nano-hydroxyapatite (HA) particles in the EDM-Oil. Moreover, the optimal solutions for processing of 316 L through the NSGA-II method are proposed in this research. Followed by the pulse-on time and HA amount, ANOVA study reports peak current being the most important parameter for the responses such RLT and SR. The augment of peak current, HA amount, and pulse-on time result comparatively lower RLT and SR than the previous studies. The best 7 solutions selected from the predicted 120 solutions following the objectives are proposed generating the Pareto frontiers. Less than 10% of the validation tests errors confirm the high accuracy of the predicted solutions. The present research proposed a potential and cost-effective method for processing of 316 L steel.