15-01-2013, 03:16 PM
ELECTRO-CHEMICAL machining
ELECTRO-CHEMICAL.pptx (Size: 3.19 MB / Downloads: 91)
INTRODUCTION
Electrochemical machining is a metal machining technology based on electrolysis where the product is processed without contact and thermal influence. The metal work piece is partially dissolved (Machined) through electricity (Electro) and chemistry (Chemical) until it reaches the required complex 3D end shape.
Unlike previous ECM techniques, the current ECM technique benefits from pulsating power supplies and vibrating axis. This concept enables processing products with a minimum process gap varying by single micrometers. The shape accuracy of the end product depends on the size of the gap.
PRINCIPLE OF OPERATION
Electrochemical machining is developed on the principle of Faradays and Ohm.
Operation principle of ECM basically considered as the reverse of electroplating with some modification.
The electrolysis principle has been in use for long for electroplating where the objective is to deposit metal on the workpiece.
In this process, an electrolyte cell is formed by the anode (work piece) and the cathode (tool) in the midst of a following electrolyte.
The metal is removed by the controlled dissolution of the anode according to the well known Faradays law of electrolysis.
ECM WITH CNC
The tool may also be connected to a CNC machine to produce even more complex shapes with a single tool.
Electrochemical machining with CNC controlled motion of universal electrodes.
Mechanism of operation
During ECM, there will be reactions occurring at the electrodes i.e. at the anode or work piece and at the cathode or the tool along with within the electrolyte.
Let us take an example of machining of low carbon steel which is primarily a ferrous alloy mainly containing iron.
For electrochemical machining of steel, generally a neutral salt solution of sodium chloride (NaCl) is taken as the electrolyte. The electrolyte and water undergoes ionic dissociation as shown below as potential difference is applied.