Investigation on the Effects of Silver Nitrate Solution Mixed Electrolyte in Electrochemical Machining of AISI 202

Abstract

Electrochemical Machining (ECM) process is widely used to machine the high hardness and poor machinable materials, however, achieving the better material removal rate (MRR) and surface roughness are the major drawbacks due to formation of spikes in the machined surface. Hence, this research work attempts to investigate the effects of Silver Nitrate (AgNO3) solution, one of the familiar oxidizing agents, on the MRR and surface roughness of the electrochemically machined AISI 202 work pieces. The selected electrolyte is 15% of NaNO3 aqueous solution and the chosen intervening variables are namely voltage, tool feed rate and electrolyte discharge rate with three levels each. Totally, eighty one experiments were conducted based on Design of Experiment (DoE) using aqueous of plain NaNO3, AgNO3 (N/10) mixed NaNO3 and AgNO3 (N/50) mixed NaNO3 in Austenitic Stainless Steel –AISI 202, one of the poor machinable materials widely used in Petrochemical Industries. The experimental results revealed that AgNO3 (N/50) solution significantly improves the performance of ECM in terms of obtaining better MRR and surface roughness of AISI 202 due to have the consistent current density across the Inter Electrode Gap (IEG). A maximum MRR of 308.034 mm3/min is achieved at 15 V, 0.1 mm/min and 8 lit/min conditions, the corresponding surface roughness of 1.14 μm Ra using AgNO3 (N/50) mixed NaNO3 aqua electrolyte, aqua electrolyte under 1V, 0. mm/min feed rate and lit/min of electrolyte discharge rate. AA minimum surface roughness of 0.6 μm Ra is obtained using AgNO3 (N/50) mixed NaNO3 aqua electrolyte at 18 V, 0.1 mm/min and 12 lit/min conditions, the corresponding MRR of 240.085 mm3/min which is 47% higher than that of plain NaNO3 aqua electrolyte.