Investigation of Ultrasonic Vibration Assisted Powder Mixed Electrical Discharge Machining for Antibacterial Coating on Implant Surfaces

Abstract Despite demonstrating a strong antibacterial property, surfaces machined and coated by nano-silver powder mixed electrical discharge machining (PMEDM) are faced with challenges relating to regulation of silver distribution as well as the spattered layer. These are among the main challenges that inhibit PMEDM’s suitability for medical implant applications, if the antibacterial coating is required. This study aims to solve these problems by introducing ultrasonic vibrations while machining Ti-6Al-4V workpiece surfaces using powder mixed electrical discharge machining involving both sinking and milling operations. During machining, the concentration of powder suspended in the dielectric fluid, the vibration amplitude as well as tool electrode size are varied. Results show that ultrasonic vibration has a capability to not only enhance the silver uniformity on the surface, but to also prevent the occurrence of a spattered layer, both of which are significantly affected by the vibration amplitude. Furthermore, for ultrasonic vibration assisted PMEDM, the tool electrode size plays an important role in the re-solidification process of the molten material since it influences the turbulence intensity, the occurrence of cavitation as well as the dielectric fluid’s flow rate in the machining gap.