Electrochemical Machining Process PDF

Electrochemical Machining Process. Electrochemical Machining, or ECM, is a method of removing metal by an electrochemical process. It is normally used for mass production and is used for machining extremely hard materials or materials that are difficult to machine using conventional methods. Its use...

Electrochemical Machining Process. Electrochemical Machining, or ECM, is a method of removing metal by an electrochemical process. It is normally used for mass production and is used for machining extremely hard materials or materials that are difficult to machine using conventional methods. Its use is limited to electrically conductive materials. This video will cover the following about electrochemical machining process. One, working principle. Two, construction. Three, working. Four, applications. Five, advantages and disadvantages. Working principle. Whenever the two electrodes, a node which is connected to positive terminal and cathode which is connected to negative terminal, is immersed in an electrolyte such as NACL. When the voltage is applied across the two electrodes, the material removal from the anode starts. The anode and cathode is placed very close to each other without touching. In ECM, the material removal takes place at atomic level, so it produces a mirror-finished surface. Ecm working is opposite to the electrochemical or galvanic coating or deposition process. Let us understand the chemical reaction taking place in this process. As the potential difference is applied across the electrode, the movement of ions starts in between the tool and work piece. The positive ions move towards the tool and negative ions move towards the workpiece. At cathode, the hydrogen ions takes electrons and gets converted into hydrogen gas. In the same way the iron atoms comes out from the anode, which is workpiece as fe plus plus ions. Within the electrolyte, the sodium ions combines with hydroxyl ions and form sodium hydroxide and ferrous ion combine with chloride ions and forms ferrous chloride. Also iron ions combine with hydroxyl ions and form iron hydroxide. In the electrolyte, the FeCl₂ and FeO₂ produced and gets precipitated in the form of sludge and settled down. In this way, the material is removed from the workpiece as sludge. The various reactions taking place in the electrochemical machining process are as follows. Construction. Electrochemical machining setup consists of following parts: power supply. It requires a DC power supply for machining purpose. Electrolyte. The electrolyte has three main roles in the ECM process. It carries the current between the tool and the workpiece. It removes the products of the reaction from the internal electrode gap, and it It moves the heat produced from the passage of the current. Tool. Tool is a replica of the shape required on the workpiece. Thank. This holds the electrolyte in which the tool and workpiece are immersed. Workpiece. Workpiece Holding table. Pressure gage. It shows the pressure at which the electrolyte is supplied to the tool. Flow meter. It shows the rate of flow of electrolyte to the machining area. Flow control valve. This helps in controlling the rate of flow of electrolyte. Pressure relief valve. In case the pressure in the supply lines increase, this pressure relief valve opens and bypasses the electrolyte to the tank. Pump. Pump helps in circulating the electrolyte. Reservoir tank, stores the electrolyte. Filter. It helps in filtering the impurities present in the electrolyte which may chalk the supply lines. Centrifuge. It helps in separating the slug from the electrolyte. Slug container. Restores the slug produced during the machining process. Working of electrochemical machining. First, the workpiece is assembled in the fixture and the tool is brought close to the workpiece. The tool and workpiece is immersed in a suitable electrolyte. After that, a potential difference is applied across the work piece, which is a node, and tool, which is cathode. The removal of material starts. The material is removed in the same manner as we have discussed in the working principle. Tool feed system advances the tool towards the work piece and always keeps a required gap in between them. The material from the work piece comes out as positive ions and combine with the ions present in the electrolyte and precipitates as sludge. Hydrogen gas is liberated at the cathode during the machining process. Since the dissociation of the material from the work piece takes place at atomic level, so it gives excellent surface finish, the sludge from the tank is taken out and separated from the electrolyte. The electrolyte, after filtration, again transported to the tank for the machining process. Application. The ECM process is used for die-sinking operation, profiling and contouring, drilling, grinding, tree panning, and micro-machining. It is used for machining steam turbine blades within closed limits. Advantages. Negligible tool wear. 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. An excellent surface finish is produced. Less heat is generated. Disadvantages. The risk of corrosion for tool, workpiece, and equipment increases in the case of saw line and acidic electrolyte. Electrochemical machining is capable of machining electrically conductive materials only. High power consumption, high initial investment cost. If you are new to ADTW