 This is Mr. Nagesh R. Thambake, Assistant Professor, Department of Mechanical Engineering, Walsh and Historic Technology, Sholapur. Today we will discuss unconventional machining part 2, in that today we are discussing the electro discharge machining process. Learning outcome at the end of this session students will be able to understand process of electro discharge machining. In this particular session we are going to discuss electro discharge machining, what is electro discharge machining, major components, working principle, advantages, disadvantages and applications. Electro discharge machining, before going to discuss electro discharge machining, first of all we will recall in what category this particular electro discharge machining can be there. Now I will tell you electro discharge machining is coming in the category of electrical system because here we are making use of electrical current. Now we will see what is electro discharge machining. Electro discharge machining is an electro thermal, non-traditional machining process where electrical energy is used to generate electrical spark and material removal mainly occurs due to thermal energy of the spark. Here EDM is mainly used to machine difficult to machine materials and high strength temperature resistance alive. EDM can be used to machine difficult geometries in small batches or even on job shop visits. Work material to be machined by EDM has to be electrically conductive. Here without electrical conductive material we cannot machine that is the one of the limitation of this particular electro discharge machining that we will see later but prior to that we must know whatever the electro discharge machining that we are using that is only for the electrical conductive material. Now we will see major components of electro discharge machining, here there are four major components are there one is electrical electric power supply. As we have earlier I told this particular EDM is coming under the category of electrical and thermal system here electrical power supply is required therefore we are having electrical power supply over here why we require the electrical power supply here we need a current that is of high frequency and this particular electrical power supply can give you high frequency current. Third one is work piece and tool third one is dielectric medium dielectric medium here that we are using that is liquid liquid kerosene and paraffin and also sometimes we are using ionizer water and last one is servo control unit servo control unit is used for maintaining the gap between tool and the work piece throughout the machining process servo control unit is maintaining the same gap throughout the machining. So here we will see the setup of the electro discharge machining here we are having a power supply once again the power supply negative terminal that is given to the tool and positive terminal that is given to a work piece. Here anode is acting like a work piece and cathode is a tool and here we are having a servo control system this system controls this particular gap whatever the gap is there that gap is controlling by this servo control system here we are having a rack with this tool and this is the pinion what happens whenever the machining is going on that time what will happen this will maintain the gap according to this control system now we will see what is the working principle of this particular electro discharge machining. So initially tool and work piece are immersed into the water and that time what will happen as the tool is acting like a electrode and work piece is acting like another electrode that time a high frequency current is transferred to the tool and that time with the help of dielectric medium the sparks are generated between this particular gap so during that spark what will happen high velocity high velocity of spark is generated due to that kinetic energy that kinetic energy kinetic energy is converted into a heat energy and lot of heat is generated over here remember 10,000 degree Celsius of heat is generated over here that spark is generated due to that spark the material is going to evaporate material is going to remove and that is evaporated and whatever the sludge is coming over here that is again removed with the help of dielectric material therefore there is no question of deposition of the chips over the work piece therefore we will get high surface finish over here. So we will see and here whatever this tool is there the tool is maintaining the gap throughout the machining with the help of this servo control system likewise the machining can occur and whatever the tool face is there that is formed exactly opposite to the work piece shape that is required please remember likewise our electrode discharge machining process can occur is occurring now we will see again in detail working principle here we will see whatever the current that we are passing with the help of these two electrodes that is nothing high high frequency current that we are passing that is called as papal plasma here I have given what is plasma the concentration would be so high that the matter existing in that channel could be characterized as plasma here we will see this is the tool and this is the electrical power supply and this particular whatever the work piece is there that we have immersed in the dielectric material now what will happen whenever the current is passed at that time due to high frequency current here sparks are generated with the help of dielectric material that time whatever the ions are there that ions is having more temperature due to that more temperature material can be removed here you can see during machining both tool and the work piece both are having varying so this wear is a low for the tool because tool is in compressive nature and therefore here work piece material is removed more as work piece material is softer than the tool therefore the removal rate of work piece work piece is more than the tool now we will see some of the advantages for this electro discharge machine it can be used to machine any material that is electrical conductive as I already told you this is only used for electric electrical conductive material non-electrical conductive material we cannot use over here it can be easily machine thin fragile sections such as waves or fins without deforming the part complex dies sections and molds are produced accurately faster and at lower price it does not involve contact between the tool and work piece so delicate sections and work material can be machined easily without any distortion it can machined complex it can machine complex shapes which is not manufactured by the conventional machine tools it is burr free process as the dielectric material is removing the burr already so after machining you will get a fine object without a burr it can produce tapered holes some of the limitations or disadvantages are there this low rate of material removal rate is there for economic production the surface finish specified should not be too fine the additional time and cost used for creating electrodes for RAM sinker idiom reproducing sharp corners on the work piece is difficult due to electrode wear power consumption is very high overcut is formed excessive tool wear occurs during machining electrically non-conductive materials can be machined only with specific setup of the process now some of the applications we will see over here it is mostly used for mold making and in die industries it is used in prototype manufacturing in aerospace automobile and electronic industries it is used for coinage die-making it is used to create small holes in variety of application it is used to disintegrate parts which cannot be disintegrate easily such as broken tools studs bolts drills drill bit and taps form of work piece here I will recommend some of the books as a reference one is workshop technology volume 2 by Robomonshi production technology by P.C. Sharma production technology a champion book