In Electro-chemical machining the gap between tool and work piece is kept as

Explanation:

ECM (Electrochemical Machining):

• The mechanism in the ECM process is like EDM concept-wise. In ECM, a high current is passed between the tool (cathode) and the workpiece (anode), through a conductive fluid (electrolyte), instead of a dielectric in the case of EDM.
• The ECM process makes use of an electrolyte and high electric – current to ionize and remove metal atoms yielding a burr-free surface.

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Controllable processes parameter and their range are given below for ECM.

• Current                                                50 to 40000 Amp
• Current Density                                   8 to 233 Amp/cm2
• Voltage                                                4 to 30 V DC
• Inter Electrode gap                            0.5 to 0.75 mm
• Electrolyte velocity                              15 to 60 m/s
• Electrolytic pressure                            0.069 to 2.7 MPa
• Electrolytic temperature                      24 to 65°C
• Feed rate                                            0.5 to 19 mm/min