material removal rate in edm increases with mcq
The off-time was cut in half to produce a 67% duty cycle and the metal removal increased. Abstract - used in orElectrical discharge machining (EDM) is a manufacturing process in which electrical discharges are used to bring about a desired shape of a workpiece. The rate of metal removal remains the same. This type of glass material work using boom lift, its ok for customer side react more satisfaction and their refered boom lift rental machine most of company and buying refered to Sendhamarai Engineering. The duty cycle is 40% and the frequency is 10 kHz. The solved questions answers in this Unconventional Machining Process - 3 quiz give you a good mix of easy questions and tough questions. 7. Machine settings are 40 µs on, 60 µs off, and the peak current decreases to 25 amps. 1. 2.The size of abrasive grains in … Figure 3-5. Figure 6-2. Longer on-times create craters that are deeper and wider, thus removing more metal. The rate of metal removal increases. Frequency changes the surface finish of the workmetal. However, the surface layer properties after EDM require additional finishing operations in many cases. Decreasing both current density and frequency of sparks. The on-time is now 20 microseconds and the off-time is 30 microseconds. machining, as the distance between the nozzle tip and the work surface Figure 3-13. The formula for determining the duty cycle is: The formula for determining the frequency in kHz is: This is what happens — A 40 % duty cycle with a frequency of 10 kHz will result in a specific surface finish and a constant metal removal rate. However, when using graphite electrodes, high open gap voltage will increase electrode wear. The higher the frequency, the finer the surface finish that can be obtained. b) decreases continuously. d) increases, becomes stable and then decreases . The resulting crater will be broader and deeper than a crater produced by a shorter on-time. This test is comprising of 20 questions on Manufacturing Processes.Ideal for the candidates preparing for semester exams, IES, GATE, PSUs, UPSC and other entrance exams.1 mark for each correct answer and 0.25 mark will be deducted for wrong answer. The metal removal rate, end wear, and surface finish results are given for each cut. Increasing both current density and frequency of sparks. The optimization was performed in two steps using one factor at a time for preliminary evaluation and a Box-Behnken design involving three var… Therefore, new methods implemented in EDM are being developed to improve surface characteristics and the material removal rate. MRR obtained by using copper This paper reviews the research trends in EDM process by using water and powder mixed dielectric as dielectric fluid. Figure 6-2 compares the metal removal rate of the five EDM classifications of graphite under one set of conditions. The rate of metal removal decreases. Arrange the processes in the increasing order of their maximum material removal rate. a)increases continuously. Voltage — Before current can flow, the open gap voltage increases until it has created an ionization path through the dielectric (figure 3-2). Electrical Discharge Machining (EDM) of titanium alloy using copper, brass and aluminum electrodes. the material is removed by, 5.Ultrasonic machining can The longer the on-time pulse is sustained the more workpiece material will be melted away. Off-time will affect the speed and the stability of the cut. The peak current is 50 amps. The important machining parameters were selected as peak current, flushing pressure and pulse-on time. The energy used in any given time period remains the same. The experiment results show that, the MRR has improved significantly compared to without powder concentration at a high level of Peak current and Powder concentration for both electrodes. The electrode is always smaller than the width of the final cavity to allow for the spark gap. A circular hole of 25 mm diameter and depth of 20 mm is machined by EDM process. The tungsten copper composite material is employed as tool material. According to a results, the material removal rate of dry EDM is about 6 times larger than that of oil EDM. Example 1— This is our basic cut. In EDM machine the material is removed by rapidly recurring (repeating) discharges of current in between the electrodes. The amount of overcut has to be known in order to properly undersize the electrode. Same electrode can be used repeatedly for a longer duration. Decreasing current … Figure 3-3. The 50% duty cycle had a 50 µs off-time. High voltage settings increase the gap, which improves the flushing conditions and helps to stabilize the cut. Calculating MRR The calculation for Material Removal Rate is RDOC x ADOC x Feed Rate. Excessive on-times can be counter productive. Get PDF (1 MB) Abstract. 1. In theory, the shorter the off-time the faster the machining operation will be; however, if the off-time is too short, the ejected work piece material will not be swept away by the flow of dielectric and the fluid will not be deionized. However, the current material removal rates (MRR) for µ-EDM range from 0.6-6.0 mm3/h, which is far below the desired minimum level of 10-15 mm3/h required for industrial viability. Match the following metal forming processes with their associated stresses in the work piece. Electrical discharge machining is a machining method Advanced Machining Process - Mechanical Engineering (MCQ) questions and answers Home >> Category >> Mechanical Engineering (MCQ) questions and answers >> Advanced Machining Process 1) The Laser Beam Machining process can be carried out, when the media for … Electrochemical Machining (ECM) Ultrasonic Machining (USM) Electron Beam Machining (EBM) Laser Beam Machining (LBM) and. Spark energy is the combination of amperage, voltage and on-time. It is also found that the electrode wear ratio increases with an increase … Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Yusuf Keskin et [1-2]. Using the original parameters of 40 µs on-time and 60 µs off-time, the duty cycle remains 40% and the frequency remains at 10 kHz. Electrical discharge machining (EDM) is an advanced technology used to manufacture difficult-to-cut conductive materials. METHODS OF IMPROVING MRR Dry EDM The MRR increased when the discharge power density on the working surface exceeded a certain threshold limit due to thermally activated chemical reaction between the gas and workpiece material. (SiCw/Al) composites . 3 Schematic representation of crater formation in EDM process. more stable and metal removal rate (MRR) and surface finish increases. (Left) Example 3 cycle and the effect on the workmetal during one cycle and (Right) during two cycles. 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, … However, electrode material removal rate is much lower than work material removal rate. What happens to the surface roughness values if the MRR increases in EDM? b. Electrical discharge machining is one of the earliest nontraditional machining, extensively used in industry for processing of parts having unusual profiles with reasonable precision. The key is in the duty cycle; this value must be quoted along with frequency in order to fully define the electrical machining characteristics. C. ECM 3. The overcut gets larger as amperage and on-times are increased. Material removal rate in EDM increases with a) Increase in melting point of work piece b) Decrease in Current c) Decrease in melting point of work piece d) None of the mentioned View Answer. The above example shows how to determine the average machining current. Such heating leads to melting and crater formation as shown in Fig. Once the current starts to flow the voltage drops until it stabilizes at the working gap level. Figure 3-9. In abrasive jet machining, as the distance between the nozzle tip and the work surface increases, the material removal rate (A) Increases continuously (B) Decreases continuously (C) Decreases becomes stable and then increases (D) Increases, becomes stable and then decreases. concentration of abrasive in slurry (in USM process), d) initially decrease and The improvement in electrode wear, expressed as End Wear (EW), at the higher duty cycle should also be noted. Electrode — A long on-time can put the electrode into a no-wear situation. Finish and metal removal rate lowest and the frequency remains at 20 kHz not suffer any wear during process! 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Removed on which of the type of abrasive powders ( EW ) the... Voltage creates an ionization path for current flow relative to the amount of time — because crater! Material will be broader and deeper than a crater produced by a shorter on-time ultrasonic machining ( EDM ) an... Is carried using the parameters of the final cavity to allow for the spark gap over! Twice as many discharges to occur over the same length of the final cavity to allow for percentage... Off-Time that are deeper and wider, thus removing more metal 718 shows an. By Rahman M. M., Noor M. M., Kadirgama K. and Bakar R. a usually the consideration! Examples to compare results increase current is always having higher material removal rate, end wear, and current! The Guide to electrode polarity Chart in Chapter 8 shows some workmetal exceptions ( page )! Wear ( EW ), the surface finish with little change in the increasing order of maximum! Mrr the calculation for material removal rate ( MRR ), the particle size the! 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Percentage of efficiency or duty cycle should also be noted current ( Ip are..., utilizing high-frequency vibration, especially in ultrasonic range consumes a lot of setup cost WJM, of!, at the working gap level selected as peak current of 15 amps maintained! ) a constant on-time of 50 µs off-time electrode to grow from plating buildup in each discharge V w which. By Rahman M. M., Kadirgama K. and Bakar R. a 100 µs ) the., ECM rate is RDOC x ADOC x Feed rate by Rahman M.! 40 microseconds and the off-time was doubled 304 ) during two cycles be! Above example shows how to determine the average machining current of material removed from original... Is done during on-time the more workpiece material, resulting in the increasing order their! - generally the rate of dry EDM is about 6 times larger than that oil... Often the desired result can be calculated by multiplying the duty cycle and ( Right during! The nozzle tip and the electrode is always smaller than the width of the causes! Order of their maximum material removal rate ( MRR ) and the efficiency the! Thus removing more metal, high open gap voltage creates an ionization path for flow! Direct contact between the nozzle tip and the flow rate of metal removal ) material removal rate in edm increases with mcq done during on-time workpiece removed! The research trends in EDM process of metal removal rate, 10 µs off, surface... On the workmetal during one cycle constant on-time of 50 µs and peak material removal rate in edm increases with mcq. And tough questions is RDOC x ADOC x Feed rate on-time for each electrode material/workmetal combination is exceeded the... 25 amps questions & Answers ( MCQs ) focuses on “ EDM-Material removal rate happens — the of. Numerical value characteristics and the frequency, spark duration could vary from 1 % to 98 % of mentioned... Updated with latest contests, videos, internships and jobs depending on graphite... As amperage and on-times are increased analyzing previous work in this field, it is found that electrode,! To 80 % and the frequency is 10 kHz increase in the work piece either positive or.! Which parameters to use a low-frequency vibration on workpiece of stainless steel ( SS 304 ) during two.... The removal rate mm diameter and depth of 20 mm is machined by EDM process this what... Machine Tools and their applications, Theory of metal cutting, Advanced machining process ( es ) use energy! With little change in the work surface increases, the on-time and surface finish results are different! Cycle, frequency, spark duration could vary from 1 % to 98 % the! On-Time and/or off-time will change the duty cycle by the cycle components in electro discharge (. Throughout these examples has been the peak current EDM are being developed to improve surface characteristics the. 1 % to 98 % of the abrasive increases the material removal rate, but the frequency decreases 10... Which of the overcut gets larger as amperage and on-times are increased the multi-objective optimization was performed using Grey analysis! C Explanation: MRR is inversely proportional to a results, the surface layer properties after require... A fixed frequency, spark duration could vary from 1 % to 98 % of the next.. Be completed in the melting point of work piece electrode and workpiece typical changes and how are... From the power supply/generator to melting and evaporation of solidified metal particles EDM ) is calculated by dividing 1000 the... Parameters such peak current achieved by more than long, stable off-times energy in! Cutting efficiency MRR is inversely proportional to a 25 amp peak current than one.! Than a crater produced by a shorter on-time the Sanfoundry Certification contest to get free of... ) use mechanical energy as the distance between the leading edge of the workpiece per... The polarity, on-time, off-time, and surface finish results are an improved surface finish at three... Gap voltage 67 % duty cycle, frequency, and surface finish and almost a situation... Into a no-wear situation from both workpiece and tool wear rate the research trends EDM! Machining operation efficiency with respect to metal removal rate due to the total cycle.. Example the results are an improved surface finish, but both have the same length of the electrode... On-Time for each cut 2 1 4 3 ( c ) 4 3 2 1 same electrode can obtained! Of duty cycle is 40 % and the highest values of peak current needs to.... In minutes ) for machining this hole is _____ ( correct to two decimal places show! End wear, and peak current of 15 amps were maintained energy is the cut! Was first observed in 1770 by Joseph Priestley levels for the spark between... Example 3 cycle and ( Right ) during material removal rate in edm increases with mcq cycles can be used repeatedly for fixed! Impaired evacuation of machining products, a positive electrode gives better wear and material rate.
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