 This is Mr. Nagesh R. Thambaki, Assistant Professor, Department of Mechanical Engineering, Walsh and East Road Technology, Sholapur. Today we are going to discuss about unconventional machining process part 3. In this particular session, we are going to discuss electrochemical machining. Previously, we have discussed what is unconventional machining process and electro discharge machining process. Now, we are going to discuss electrochemical machining process, learning outcome. At the end of this session, students will be able to understand process of electrochemical machining. In this particular session, we are going to discuss what is electrochemical machining, major components, working principle, advantages, disadvantages and applications. Now, what is electrochemical machining process? Nonconventional machining system in which metal is removed by electrochemical process characterized as reverse electroplating means it removes metal instead of adding it. Normally used for mass production and for hard materials that are difficult to machine using conventional machining process. Both external and internal geometries can be machined by this particular process. Now, we will see what are the major components of this electrochemical machining process. The main components of ECMR, this is the schematic figure in which we are having the various components. First important component is power supply. Here we are supplying the power as our process is electrochemical process. We need to supply electric current with 40,000 ampere current that we need to pass with 2 to 30 volts of DC power. This is the electrical supply. Now, electrolyte, electrolyte we are using over here that is the NaCl sodium chloride that electrolyte we are using over here that electrolyte we are using. Now, tool. Tool is having a very high surface finish and very high surface finish that we are using. This is tool which is having internal hole to pass the electrolyte. The control system, the control system which gives the constant feed to the work to get a minimum tolerance. Within tolerance, we will get the machining. Therefore, this constant feeding will be acting with the help of control system. Now, entire machine. This machine we are using for electrochemical process. Here there is a electrolyte. Electrolyte is pumped through the pump with high pressure. And here there is a filter. Whatever the sludge is formed over here that will be going to filter in this particular filter. And then the temperature is controlled over here. That particular electrolyte is passed through this tool to carry out the reaction. Now, we will see the working principle of electrochemical machining process. Now, we will think about this. This particular whatever the electrochemical machining process is there. What is the principle of this process? Now, please think. This particular ECM works on the principle of paradise law of electrolysis. ECM working is opposite to the electrochemical or galvanic coating or deposition process. Here, material is going to be removed. In electroplating process, we are going to add the material. During electrochemical machining process, the reactions takes place at the electrodes. That is at the anode means workpiece and at the cathode means tool and within the electrolyte. Now, let us take an example of machining low carbon steel, which is mainly composed of ferrous alloy. And here we are using an electrolyte NaCl that is a sodium chloride. Now, here sodium chloride, whenever we are passing the current that time, it is getting ionized Na plus and plus Cl minus. And here also what is going to ionize that is H plus and OH minus. Now, as the potential difference is applied across the electrode, the moment of ion starts in between the tool and the workpiece. The positive ions moves towards the anode and negative ion moves towards the cathode and negative ions moves towards the workpiece that is anode. Now, here at cathode, the hydrogen ions takes place, takes electron and gets converted into hydrogen gas. Please see over here. This is the hydrogen plus and there is electron and we will get a gaseous hydrogen over here. In the same way, the iron atoms comes out from the anode from the workpiece as Fe plus plus ions and it is forming a ferrous. Within the electrolyte, the sodium ions combines with hydroxyl ions and forms sodium hydroxide. And ferrous ions combine with chloride ions and forms ferrous chloride. Also, iron ions combine with hydroxyl ions and form iron hydroxide. Now, here we can see Na plus OH minus, we will get NaOH that is sodium hydroxide and here Fe 2 plus plus 2 Cl minus, we will get Fe Cl 2 that is ferrous chloride. In the electrolyte, the Fe Cl 2 and Fe O H twice produced and get precipitated in the form of sludge and settle down. In this way, material is removed from the workpiece as a sludge. Here we can see, here we can see how the moment of electrons are there. Here we can see Fe plus plus and O H minus will form a ferrous hydroxide and here Fe 2 plus and Cl 2 minus, we will get Fe Cl 2 so that we will get ferrous chloride as a sludge. So, with the help of these two sludge, the material is getting removed. Now, these processes having certain advantages. Negligible tool wear is there. Complex and concave curvature parts can be produced easily by the use of convex and concave tools. No forces and residual stress are produced because there is no direct contact between tool and workpiece. Excellent surface finish is produced as here there is a control system and as that is giving a continuous constant feed. Therefore, we are getting excellent surface finish. Less heat is generated because here whatever the material removal process is there that is reversed to electroplating. Therefore, less heat is generated over here. Now, certain limitations or disadvantages are there. The risk of corrosion for tool or workpiece and equipment increases in the case of saline and acidic electrolyte. Here whatever the workpiece folding device is there that we are taking a non-electrical conductive material and whatever the workpiece is there that we are taking electrical conductive. Therefore, in certain cases corrosion will occur but in many cases we are using the material that are non-corrosive as a tool. Electrochemical machining is capable of machining electrically conductive materials only. This is one of the limitations because whatever the non-conductive non-electrical conductive materials are there that we cannot machine over here. As we are passing the electrical current therefore definitely we want a workpiece to be of electrical conductive. High power consumption will be there. As already I told you 40,000 ampere current that we are passing for carrying out this particular machining process. Therefore, high power will be consumed and high initial investment cost is there. Initial cost is high now certain applications are there. The ECM process is used for die-sinking operation, profiling, contouring, for drilling, grinding, tree panning and micromachining. It is used for machining steam turbine blades within close limits. Now for further information I will recommend some of the books that is one is Workshop Technology, Volume 2 by Raghu Moshi, Production Technology by PC Sharma that is HMT Handbook. These books that you can refer for more information. Thank you.