Electric Discharge Machining: A Promising Choice for Surface Modification of Metallic Implants

Introduction

Electrical discharge machining (EDM) has its roots in the 1770 discovery of the erosive properties of electrical discharges by English scientist Joseph Priestly. In the 1930s, attempts were made to a gadget that uses electrical discharges for the first time to work with metals and diamonds. Intermittent arc discharges in the air between the tool electrode and workpiece linked to a DC power source were what caused erosion. Because to the overheating of the cutting region, these procedures were not particularly accurate and may be classified as “arc machining” as opposed to “spark machining” (Ho and Newman, 2003).

With the advent of the internet, the world has become a much smaller place, and the world has become a much smaller place as well (Lazarenko, 1943). A controlled procedure for machining materials was created by channelling the destructive power of an electrical discharge.

In the 1950s, the RC (resistance-capacitance) relaxation circuit was created. It offered the first reliable, constant control of pulse timings as well as a straightforward servo control circuit to automatically identify and maintain a certain gap between the electrode (tool) and the workpiece. In the 1950s, the RC circuit was widely employed and eventually served as a template for further advancements in EDM technology.

When three American employees came up with the idea of employing electrical discharges to remove damaged taps and drills from hydraulic valves, similar claims were made at around the same time. This study served as the foundation for the vacuum tube EDM machine and an electronic circuit servo system that supplied the ideal electrode-to-workpiece separation (spark gap) for sparking without the electrode actually touching the workpiece (Jameson, 2001). Nevertheless, the introduction of Computer Numerical Control (CNC) in EDM in the 1980s was what really made a difference in terms of raising the efficiency of the machining process. Modern EDM machines are now so reliable as a result of ongoing process development that they may be used 24/7 while being monitored by an adaptive control system. Any material that is electrically conductive may be machined with this method, regardless of its hardness, shape, or strength (Abu Zeid, 1997).