Evaluation of surface integrity in electrochemical micromachining of A286 super alloy

Abstract

Surface integrity of micro components is a major concern particularly in manufacturing industries as most geometry of the products must meet out necessary surface quality requirements. Advanced machining process like electrochemical micro machining possess the capabilities to machine micro parts with best surface properties exempting them from secondary operations. In this research work, different electrolytes have been employed for producing micro holes in A286 super alloy material to achieve the best surface quality and the measurement of surface roughness and surface integrity to evaluate the machined surface are carried out. The machined micro hole provides detailed information on the geometrical features. A study of parametric analysis meant for controlling surface roughness and improvement of surface integrity has been made to find out the suitable parameters for machining. The suitability of various electrolytes with their dissolution mechanism and the influence of various electrolytes have been thoroughly studied. Among the utilized electrolytes, EG + NaNO3 electrolyte provided the best results in terms of overcut and average surface roughness.

Study on the influence of auxiliary electrode and magnet on electrochemical machining of SS304 using NaCl and NaNO3

“…The positive sodium ions and the negative hydroxyl ions present in the electrolyte combine to form sodium hydroxide. This results in the formation of ferric chloride and sodium salt precipitates as shown in the equation [15]. Meanwhile, the passive film in SS304 (workpiece) had been broken down by some of the chloride ions, and this caused a discontinuity in passive film (pit), the Cl − ions and hydrogen ions migrate into the pit formed which decrease the pH of the electrolyte present in the pits [35] as shown in equation (1).…”

“…Due to the passive nitrate ions, the NO 3 ions get accumulated near the workpiece and the anodic dissolution of SS304 takes place and they react with the Fe+ions forming a neutral compound 3Fe(NO 3 ) 2 . Iron nitrate and hydroxides of sodium salts were formed during the electrolytic reaction of Fe with nitrate as shown in equation (2) [15].…”

“…A woven fabric mask was used in electrochemical micromachining process with sodium nitrate (NaNO 3 ) electrolyte to improve the process accuracy [14]. Holes with better accuracy and surface finish were obtained when ethylene glycol (Passive nature) and sodium nitrate were used as electrolyte [15]. In Kerosene-submerged jet electrochemical machining (Jet-ECM) it was observed that jet orientation had a major influence in the removal of metal oxides from the machining zone [16].…”

Real-time monitoring of process current and its correlation with micro-feature accuracy and surface topography in electrochemical micromachining of nitinol

“…The usage of ethylene glycol (EG)-based solutions as an electrolyte in ECMM is on the rise, particularly in case of metals like titanium [5], nickel alloys [15], iron-based superalloy [16], and metallic glass [17]. These organic-based electrolytes are less conductive in comparison to their aqueous counterparts and hence provide better accuracy due to the low machining rate.…”