Why black precipitate during electrochemical machining?
August 6, 2008 sir, am a pg student. As a part of a project work I want to make holes on the cut face of 12 mm rod.I use electrochemical machining as a choice. I selected mild steel as anode and copper rod of 20 mm as cathode.The copper rod has 72 projections of 1 mm diameter and 1 mm height.This projections are to be drilled on the work piece (mild steel).While machining a black(gray) precipitate is formed which prevents further machining (I think).I tried pouring HCl into the electrolyte.The electrolyte am using is NaCl of concentration 50 grams per liter.Current used is 0.5 ampere and electrode gap is 0.5 mm. how can I avoid this black precipitate. what I will do? I tried by using a motor to stir the electrolyte. expecting a fast response…
