Electrochemical Machining: Introduction, working Principle, suitable diagram,materal used, parts of usage, application, advantage, disadvantage

Introduction:-

     Electrochemical Machining (ECM) is based upon Faraday's law of electrolysis. Faraday's law states that the the mass of a metal altered by the electrode is proportional to the quantity of electrical charges transferred to that electrode.
In ECM the removal of metal is controlled by the anodic dissolution in the electrolyte. 
In ECM -
 The workpiece acts as the anode
The tool act as cathode.
The electrodes should be placed closely with a gap of about 0.5 mm .
The anodes and cathodes should be immersed into electrolyte. (Here Sodium Chloride).




Working Principle of Electrochemical Machining:-


The main principles of ECM are as follows - 

• A potential difference is maintained between the electrodes as a result ions existing in the electrolytes migrate towards the electrodes. 
• Conventionally positively charged ions are attracted towards the cathode and negative ions are attached towards to the anode. And thus flow of current is initiated in the electrolyte. 
• The set-up is kept stationary and tool is fed linearly. 
• The desired amount of metal is removed because of ion migration towards the tool. 
For keeping the tool safe from damage a continuous supply of electrolyte is ensured by pumping it at high pressure (15kg/cm2). 
In this process the temperature generated is very low and no spark is produced and thus there isn't any scope of metallurgical changes in the job. 
• When electricity is supplied to the metallic ions of the w/p is pulled out. The positive ions of the metal reacts with the negative ions present on the electrolytic solution and hydroxides of metal and other components. This hydroxides are precipitated and washed away by the electrolytic solutions.  
In Electrochemical Machining the tool and workpiece doesn't come in direct contact with each other so negligible wear and tear is observed. 
• Metal removal rate is high and voltage supplied is very low. 
• The metallic workpiece is not damaged due to thermal stresses. 
• Dimensions up to 0.05 mm can.

Parts of Electrochemical Machining:-


Application of Electrochemical Machining:-

• ECM is mainly used in the areas where conventional machinig techniques are not feasible . One of the main applications of ECM is found in the aerospace industries where accuracy is very important when complex shaped difficult to machine materials are needed to be machined. 
• Different Industrial techniques have been developed on the basis of Electrochemical Machining Such as 
                a. Electrochemical Cutting 
                b. Electrochemical ECM 
                c. Electrochemical broaching 
                d. Electrochemical drilling 
                e. Electrochemical deburring 

Advantage of Electrochemical Machining:-

• Accurate Machining 
• No direct contact between tool and job. 
• Negligible wear and tear of the tool. 
• Environment friendly 
• no thermal or mechanical stress is induced on the tool.
• There is no contact between workpiece and the tool so its is possible to machine non-rigid and open w/p. 
• Jobs with complex geometric shapes can be machined with ease accurately and repeatedly. 
• ECM is a time saver when compared to conventional machining. 
• During drilling several holes can be done at once.  
• Deburring can be done in hard to access areas. 
• Fragile and brittle materials which are prone to damage can be machined easily in ECM without cracking or breaking. 
• Surface finish up to 25 μ in can be achieved. 

Disadvantage of Electrochemical Machining:-

• Sometimes this process is costly because the equipments are expensive. 
• Continuous supply of electrolytic solution is mandatory. 
• Steady voltage or potential difference should be maintained. 
• Rigid fixturing is required to withstood the high flow rate of electrolytes. 
• Designing the tool is arduous because it must be insulated to maintain the perfect 
conducting paths towards the workpiece. 
• Corrosion free material is needed for the structure and the electrolyte handling unit. 
• If hydrogen is liberated at the tool surface then it is possible to suffer from hydrogen-embitterment of the surface. 
• There is possibility of damages because of sparks. 
• Conventional machining techniques produce more improved fatigue properties than ECM.

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