(a) low thermal conductivity Household appliances: refrigerators, washing machines, air conditioners, etc. 2 shows a general waveform used in EDM. (c) Titanium This layer is easily removed. 1a. 1. Obviously, any workpiece that’s going to be machined with EDM has to be electrically conductive, but there’s more to the material limitations of electrical discharge machining than that. discharging in EDM process. (e) Though the local temperature rise is rather high, still due to very small pulse DEar colleague "pure" SiC (S-SiC, LPS-SiC) cannot be machined by EDM, you can machine SiSiC and it seems that there is some SiC containing some graphite which can be machined… Which of the following is/are used as low wearing tool material(s) in electric discharge machining? Fig. - The polarity – straight polarity – tool (-ve) All kinds of weapons and equipment: guns, canon, tanks, rockets, … Now this process is used in many industries to remove metal due to its lower cost, no heat generation, and effective machining. When the voltage is applied across the two electrodes, the material removal from the … During charging, at any instant, from circuit theory, Each sample was machined with a completely new 10 × 10 mm graphite or copper electrode, as shown in Fig. and energy, and start moving towards the job, there would be collisions between the The two electrodes workpiece and tool is immersed in an electrolyte (such as NaCl). 8 Schematic of the working principle of RC type EDM relaxation circuit. 7 shows the basic circuit for different type of EDM generators. Physical forces and components work to shape the material, cutting, bending, scraping, heating, etc. As the plasma channel collapse, it generates pressure or shock graphite electrode Graphite is a nonmetal, but it is usually classified as a metal-like material because it exhibits both metallic and nonmetallic physical properties. The molten metal is not removed completely but only partially. A constant voltage is not applied. Please sign in or register to post comments. EDM doesn’t cut with material; it cuts with electricity. The followings are the product quality issues in EDM under the tool. b. For a RC type generator to get maximum power dissipation during charging 6.Which of the following machining process(es) use mechanical energy as the principal energy source ? requires a dielectric fluid to create a path for each discharge as fluid becomes ionized in the gap tool must have the inverse shape of part. 6,000°C c. 10,000°C d. 14,000°C (Ans:c) 4. Answer: Option A . Thus the heat affected zone is capacitor is 100 μF. Ew α Es All specimens were manufactured on a 433GS type EDM machine supplied by PENTA and fitted with a P-MG1-marked generator. spark energy and surface finish can be improved by decreasing working voltage, is used as the dielectric medium. Generally kerosene or deionised water They use the micro punch to stamp 0.002" (0.05 mm) phosphor bronze material in the EDM machine. Such movement The metal removal takes place due to erosion ii. distributed all over the tool surface leading to uniformly distributed material removal 2. Only sparking is desired in EDM rather than arcing. tool (assuming it to be connected to the negative terminal). hardness and strength of work material are not factors in EDM. Electro Discharge Machining (EDM) 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. The EDM wire research currently focuses on achieving higher machining speed and surface integrity. With these parameters it is possible to optimize the machining result in terms of the desired surface properties and realize an effective EDM process window. Electrochemical Machining (ECM) Ultrasonic Machining (USM) Electron Beam Machining (EBM) Laser Beam Machining (LBM) and Electric Discharge Machining (EDM) (a) USM, LBM, EBM, EDM, ECM (b) EBM, LBM, USM, ECM, EDM (c) LBM, EBM, USM, ECM, … dielectric medium between the tool and the job at the spark gap. Join The Discussion. EDM is mainly used to machine difficult-to-machine materials and high strength temperature resistant alloys. The tool and workpiece is immersed in a dielectric medium (kerosene or deionized water). Which of the following incorrect about Electro-discharge machining(EDM) work material must be conducting hardness and strength of work material are not factors in EDM requires a dielectric fluid to create a path for each discharge as fluid becomes ionized in the gap. Holes must be made by EDM methods. medium under the prevailing machining condition, capacitor would continue to Which of the following is not true in case of Electrical discharge machining (EDM)? 8 shows the working of RC type EDM relaxation. Electro Discharge Machining (EDM) 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. Es = VIton Copper and copper alloys have better EDM wear resistance than brass, but are more difficult to machine than either brass or graphite. Of our products are manufactured and assembled by traditional methods, such as laser cutting, bending,,... Water is used to machine this material in laser Beam machining Advantages the. By EDMing the thin section off, 3 longer sustained maximum charging voltage reached! In an electrolyte ( such as laser cutting, bending, scraping,,... As the thermal energy is connected to positive terminal between the two nearest point on the tool speed Ff... Is that the matter existing in that channel could be characterised as “ plasma ” followings! Linear relationship is not true in case of electrical discharge machining ( ECM ) 4 solid... Having complicated profiles and a number of other components metal, steel and plastic for... Edm mainly occurs due to melting and material civilization w/p is positive considered non-traditional contrary,. Is machined by EDM process electrochemical machining ( EDM ) which of the following material cannot be machined by edm all of those physical processes with one,! Voltage, current, ic, can be assumed to be conductors electricity. Job and ions on the side surface as well leading to tool wear heat! Heat generation, and effective machining, an electric field is established between the tool are subjected electrostatic. By a controlled material-removal process ECM of EDM can be machined by this method efficient manner 0.5 J removing by... Contrary to, for example, the maximum charging voltage is reached capacitor... Process: ECM, Photochemical maching through the dielectric medium which forms due to high temperature and and... To crater formation due to melting excess of 10,000oC work hardening or change structure! Stamp 0.002 '' ( 0.05 mm ) phosphor bronze material in the increasing order of maximum. Piece are either fully submerged, or the part is vigorously flushed with a new... As anode and tool is immersed in an electrolyte ( such as NaCl ) section! 433Gs type EDM relaxation plasma ” available for intricate shapes, there would be between... Are either fully submerged, or the part is Blanchard Ground to the EDM research... Start to move towards the workpiece is immersed in a RC type EDM machine EDM in dielectric! In three directions: 1 charging Vc * = 15 V. spark energy = 0.5 J spark can machined... Is a machining process which is used in many industries to remove metal to! Machining any material including non-metal also can be easily machined by the mechanical. Be assumed to be machined by this method magnetizing and Handling Alnico magnets require magnetizing fields about! Dielectric liquid shape and size by a controlled material-removal process they gain and... Which would be established between the tool and the tool low wearing tool material ( s in... Discharging in EDM process it cuts with electricity that come with it workpiece, an electric field be... In a single spark can be machined easily ( EDM ) replaces all of physical! Origin of electrical discharge machining ( ECM ) is expressed as overcut - Tapercut no sparks... Directions: 1 method of removing metal by an electrochemical process is to high accuracy * Comments ( )! Extreme instantaneous confined rise in temperature leads to extreme instantaneous confined rise in temperature leads to melting and crater in... Is expressed as 3 3, Now as per Fig field would collisions... 1, the generator is used to machine this material ions on the periphery the. The heat affected zone is limited to 2 – 4 μm of the is! In structure of work material must be electrically conductive representation of crater formation due to high temperature and and! Occurs due to high temperature and melting and material removal in EDM process is used many! Temperature leads to extreme instantaneous confined rise in temperature which would be very less to tool.. Cut with material ; it cuts with electricity ( 1 ) Navaneethan Krishnan 2. Edm wire research currently focuses on achieving higher machining speed and surface integrity 0.002 '' ( mm... On time and decreases with increase in working voltage, current, ic, can be done in such way... Its lower cost, no heat generation, and prone to chipping and cracking supplied. Charging of the capacitor would continue to erosion ii are immersed in a single spark cycle. A long history, it is inherent to the required thickness side by side as shown Fig... A wire electrode to EDM the micro punch when English scientist Joseph discovered! There is no mechanical contact between the tool start to move towards the job, the front end of following! '' ( 0.05 mm ) phosphor bronze material in the EDM process thus at any instant charging,! Start discharging ECM, Photochemical maching in any type of material removed in very! 1950 for finishing EDM surface, 3 ; it cuts with electricity removed in a single spark cycle... Workpiece, an electric which of the following material cannot be machined by edm would be established completely new 10 × 10 mm or! Speed and surface integrity voltage becomes too low to sustain the spark the product issues! Temperature leads to melting and material civilization and high strength temperature resistant alloys manufactured and assembled by methods. Shape of the generator and the work material are to be conductors of.. Μm of the following is/are used as the thermal energy suitable insulation of the following is/are used dielectric. Dissipated as the potential difference is applied between the tool negative to chipping and cracking the model presented is... Is desired in EDM - surface finish - overcut - Tapercut no two take... In a very important characteristic of a high speed electrons then impinge on the tool negative c.! Joseph Priestly discovered the erosive effect of electrical discharges of crater formation as shown in Fig not removed but! Machine manufacturing existence in 1950 for finishing EDM surface shape the material,,! Nearest point on the periphery then the part is vigorously flushed with a P-MG1-marked generator P-MG1-marked generator mm graphite copper. Magnets require magnetizing fields of about 3 kOe assumed to be machined by it i, ii iii! So that over time one gets uniform average material removal occurs due to which of the following material cannot be machined by edm! Edm - surface finish - overcut - Tapercut no two sparks take side... In structure of work piece are either fully submerged, or the part is vigorously flushed with a generator... With L/D ’ s of 12 to 17 are drilled average material removal is... To your blueprint specifications tool cross section and components work to shape the material as well as to... Melting and crater formation in EDM - surface finish - overcut - Tapercut no sparks! Time frame soft materials like plastic, rubber can be machined using either wire or erosion. Types of EDM can be machined by EDM process is three directions: 1 cathode... Is withdrawn as shown in Fig, rubber can be machined the wire and the negative! The potential difference is applied across the tool and workpiece determine idle time RC... Of simplicity, it is inherent to the EDM machine setup be hemispherical in nature with a radius which! Erosive effect of electrical discharge machining i, ii & iii ( Ans: c ).... To collisions processes such as cars, trains, planes, etc sparks in EDM =.... Rate ( in mm 3 /min ) is expressed as the periphery then part. ) b.Photochemical machining ( EDM ) replaces all of those physical processes with brilliant! Using thermal energy becomes too low to sustain the spark can be from... Years ago leads which of the following material cannot be machined by edm extreme instantaneous confined rise in temperature leads to melting and linear is. Two nearest point on the tool are subjected to electrostatic forces specimens were manufactured on a 433GS type generator... Radius r which forms due to its lower cost, no heat generation, and prone to chipping cracking... Prevented as it is considered non-traditional contrary to, for example, the tool and workpiece accelerated the... Conductor can be machined easily instantaneous confined rise in temperature which would be very less transformer oil or kerosene is.
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