The potentiality of sinking EDM for micro-impressions on Ti-6Al-4V: keeping the geometrical errors (axial and radial) and other machining measures (tool erosion and work roughness) at minimum

Abstract

Ti-6Al-4V is a material of high interest in various industrial sectors including biomedical, automotive and aerospace. Conventional means of machining encounter different types of difficulties. Electric discharge machining (EDM) is not a contest of hardness. Circular impressions of micro-depth are produced in Ti-6Al-4V using four different electrode materials including aluminum, brass, graphite and copper, each assigned positive and negative polarity. In order to get precise control over the geometry of micro-impressions dimensional accuracy and tool wear must be controlled. Thus, EDM performance has been evaluated in terms of axial dimensional error (D.E_Axi), radial dimensional error (D.E_Rad), tool length reduction (TLR), and surface roughness (SR). Since the EDM process is stochastic in nature therefore in addition to tool polarity only two factors are considered as variables, i.e. discharge current and pulse-time-ratio (ration of on-time to off-time). The behaviors of each of the four electrode materials are compared together under each of the two polarities and two variables for each of the four response characteristics. The search is carried out to select the most appropriate tool electrode polarity (common for all responses) and a single common electrode capable of minimizing all the four response measures simultaneously. Moreover, microstructures of the machined impressions are discussed. Without any compromise in the minimum values of response measures, no single polarity and a single electrode are found common. However, with a slight compromise over the machining measures negative tool polarity and copper electrode served the purpose of set objectives (minimum of D.E, TLR, and SR). The expanse of compromise is found to be ≤ 50 µm in axial and radial dimensional errors, 0.8 µm in surface roughness and no compromise in tool length reduction if the copper electrode is assigned with negative polarity.

Surface texturing of non-toxic, biocompatible titanium alloys via electro-discharge

“…Various methods have been utilized to obtain the biocompatible substrates for the impalnts, whereas, amongst all the Electro Discharge Machining or in other term this process is also termed as Electro discharge treatment (EDT) is the novel technique in the field of surface alterations (Devgan & Sidhu, 2019). This technique utilized thermo-electrical energy source that has the potential to offers desired morphology with precise dimensional accuracy (Ahmed, 2019). In this process, high-frequency electric sparks produced between the tool electrode and workpiece which produces high-temperature heating zone.…”

Reducing the geometrical machining errors incurred during die repair and maintenance through electric discharge machining (EDM)

“…The reason behind the selection of these variables is due to their significant role proved on other machining aspects as evident in literature [22,25,31]. The physical properties of all tool electrodes and workpiece which play a significant role during electric discharge machining are mentioned in Table 2 [37,38]. The tool electrodes used for experimentation are copper, graphite, and tungsten carbide.…”

Achieving the Minimum Roughness of Laser Milled Micro-Impressions on Ti 6Al 4V, Inconel 718, and Duralumin

“…The suitable tool material and EDM parameters are suggested to produce micro-impressions with minimum surface roughness. The graphite tool allowed the highest surface roughness (R a 8.85 µm), whereas aluminum electrode resulted in a minimum roughness (1.05 µm) of the micro-impressions produced by Ahmed et al [ 20 ]. Similarly, micro-grooves have been produced in the titanium alloy as reported by Lei et al [ 21 ] through EDM.…”