material removal rate in edm increases with mcq

$ 4\times10^4\;IT^{-1.23} $ , where $ I=300 $ A and the melting point of the material, $ T=1600^\circ C $ . Figure 3-11. Workmetal — One theory is that the metal melts to the maximum depth and at that point the heat spreads outward without melting more metal and without sustaining the melting temperature at the bottom of the crater. Electrical discharge machining is one of the earliest nontraditional machining, extensively used in industry for processing of parts having unusual profiles with reasonable precision. 20.In AJM, removal of metal Variations in metal removal rate (in3/hr) occur because of differences in spark frequencies due to changes in nonproductive time (off-time). The optimization was performed in two steps using one factor at a time for preliminary evaluation and a Box-Behnken design involving three var… However, the surface layer properties after EDM require additional finishing operations in many cases. The polarity, on-time, off-time, and peak current (Ip) are the basic machine settings. Longer on-times create craters that are deeper and wider, thus removing more metal. The previous 50 amp peak current will be changed to a 25 amp peak current setting (figure 3-9). Electric Discharge Machining (EDM) has metal removal rate of about 10-20 mm 3 /s. 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, … Electrical discharge machining is a machining method High voltage settings increase the gap, which improves the flushing conditions and helps to stabilize the cut. 3 Schematic representation of crater formation in EDM process. 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. Average current is the average of the amperage in the spark gap measured over a complete cycle. The removal rate and surface roughness in EDM increase with. Figure 3-9. When the optimum on-time for each electrode material/workmetal combination is exceeded, the Metal Removal Rate (MRR) actually starts to decrease. These changes plus varying the peak current will affect the metal removal, electrode wear, and finish. ... (b) 2 1 4 3 (c) 4 1 2 3 (d) 4 3 2 1. Such heating leads to melting and crater formation as shown in Fig. a) Decreases b) Increases c) Increase and then decrease d) All of the mentioned 10. C. ECM 3. Choice (4) Response; a. Melting and Evaporation. %SiCw/2124 Al is >25 vol. increases, the material removal rate, c) decreases, becomes Electrochemical Machining (ECM) Ultrasonic Machining (USM) Electron Beam Machining (EBM) Laser Beam Machining (LBM) and. Off-time will affect the speed and the stability of the cut. This set of Advanced Machining Processes Multiple Choice Questions & Answers (MCQs) focuses on “EDM-Material Removal Rate”. a) Decreases b) Increases c) Increase and then decrease d) All of the mentioned 10. What happens to the surface roughness values if the MRR increases in EDM? Machine settings are 40 µs on, 60 µs off, and 50 amps peak current. 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 … The cycle is completed when sufficient off-time is allowed before the start of the next cycle. Decreasing both current density and frequency of sparks. 5: Properties and Characteristics of Graphite, EDM ELECTRODE MATERIAL CLASSIFICATIONS AND APPLICATIONS, 6: Five Key Factors in Electrode Material Selection, 7: Practical Applications of The Five Key Factors In Electrode Material Selection. Polarity refers to an electrical condition determining the direction of the current flow relative to the electrode. The time (in minutes) for machining this hole is _____ (correct to two decimal places) applications wherein increased importance is placed on the graphite electrode material utilized. The material removal increases with the increase in machining time, but the machining rate is different for different workpiece materials. Machine settings are 20 µs on, 30 µs off, and 50 amps peak current. The duty cycle is calculated by dividing the on-time by the total cycle time (on-time + off-time). 1. c. LBM, EBM, USM, EDM, ECM. This study focused on the machining of SKD61, SKD11, and SKT4 … What happens to the material removal rate if the sparks are very less in EDM? This is why performance charts can be helpful. Expected results — Relatively unchanged surface finish, but the metal removal rate should double. Machining parameters for Example 4 and the effect on the workmetal during one cycle. The following examples show typical changes and how results are influenced by these changes. takes place by bombardment of fine grained particle. stable and then increases, d) increases, becomes The objective of this paper is to study the influence of operating input parameters of copper electrode on material removal rate of EN-19 material followed by optimization. MRR = 0.28 in3/hr EW = 2.5 % SF = 350 µin Ra. By Rahman M. M., Noor M. M., Kadirgama K. and Bakar R. A. 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. During EDM operation, electrode material is also removed gradually along with workpiece material. The duty cycle increases to 80% and the frequency remains at 20 kHz. 22.4 In water jet cutting and abrasive water jet cutting, the separation between the nozzle opening and the work surface is called which one of the following: (a) gap, (b) gap size, (c) orifice, (d) overcut, or (e) standoff distance? The electrical discharge machining process is hampered by a low material removal rate (MRR), high tool wear, and low quality of machined surface, which limit its applicability. It was first observed in 1770 by Joseph Priestley. Moreover, material removal rate greatly increases when these two factors are increased, where these tendencies are the ones that one could expect a priori, as more energetic pulses usually lead to a higher material removal and on the other hand, an increase in the ionisation or breakdown voltage results in an increase in both the discharge energy and the work gap, giving the latter a better flushing … 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. 6.Which of the following According to a results, the material removal rate of dry EDM is about 6 times larger than that of oil EDM. The surface finish at all three duty cycles changed very little because the crater created by the spark did not change. Frequency changes the surface finish of the workmetal. MRR = 0.70 in3/hr EW = 6.3 % SF =300 µin Ra. Electrical discharge machining (EDM) is an advanced technology used to manufacture difficult-to-cut conductive materials. 7. MRR = 0.80 in3/hr EW = 2.5 % SF = 400 µin Ra. 1. Machining parameters for Example 1 and the effect on the workmetal during one cycle. In the previous example, varying the frequency improved the finish, but in this example the results are quite different. Experiments were conducted by selecting different operating levels for the three parameters according to Taguchi’s Design of Experiments. The rate of metal removal increases. Choice (4) Response; a. EBM, LBM, USM, ECM, EDM. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. 20. Arrange the processes in the increasing order of their maximum material removal rate. When the mass flow rate of the abrasive increases the material removal rate also increases. Example 2 — This cut shows a frequency change. The primary objective in EDM of materials is always having higher material removal rate (MRR) in order to improve the productivity. used for the tool in Ultrasonic machining is of the order of, 4.In Ultrasonic machining, 22.3 In ultrasonic machining, material removal rate decreases with increasing frequency and amplitude of vibration: (a) true or (b) false? (MRR). used for converting electrical impulses into mechanical vibration in USM. The preset voltage determines the width of the spark gap between the leading edge of the electrode and workpiece. 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, … material is not generally machined by USM, 11.Increasing volume This contains 10 Multiple Choice Questions for Mechanical Engineering Unconventional Machining Process - 3 (mcq) to study with solutions a complete question bank. When the melting point and latent heat of melting increases in EDM, the. $ 4\times10^4\;IT^{-1.23} $ , where $ I=300 $ A and the melting point of the material, $ T=1600^\circ C $ . The material removal rate depends on type of abrasive powders. 2.The size of abrasive grains in … Electrical discharge machining, generally known as EDM, is a thermoelectric process of non-conventional machining, where electrical discharges occur between two electrodes immersed in a dielectric fluid promoting heating, vaporization and removal of material. The polarity of the electrode can be either positive or negative. Analyzing previous work in this field, it is found that electrode wear and material removal rate increases with an increase current. This research work describes the effect of powder concentration in dielectric fluid during electrical discharge machining (EDM) of mild steel on material removal rate (MRR), electrode wear rate (EWR) and work surface roughness (Ra). All work (metal removal) is done during on-time. 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 material is removed by, 5.Ultrasonic machining can 21.In WJM, removal of metal Effects of duty cycle changes on metal removal rate and surface finish. The key is in the duty cycle; this value must be quoted along with frequency in order to fully define the electrical machining characteristics. more stable and metal removal rate (MRR) and surface finish increases. The constant value throughout these examples has been the peak current. What happens to the material removal rate if the sparks are very less in EDM? Figure 3-3. 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. However, when using graphite electrodes, high open gap voltage will increase electrode wear. Figure 3-8. A circular hole of 25 mm diameter and depth of 20 mm is machined by EDM process. significantly increases the surface finish and machining efficiency of EDM process. The above example shows how to determine the average machining current. The result is an improved surface finish with little change in the metal removal rate. This work presents an attempt to use a low-frequency vibration on workpiece of stainless steel (SS 304) during EDM process. All of the examples used positive polarity, tool steel as the workpiece, POCO EDM-3 as the electrode material, and a 5-minute cutting time. Figure 3-12. In the present work, an attempt has been made to model material removal rate, electrode wear rate, and surface roughness through response surface methodology in a die sinking EDM process. become more stable thus increasing the material removal rate and improve the surface quality as compared to conventional EDM. Figure 3-6. Example 4 — This cut shows a peak current change. 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 ... I.C Engines Multiple Choice Questions with Answers - Set 02. Each spark, regardless of off-time variation, will remove the same volume of workpiece material, resulting in the same surface finish value. This produces a smoother finish with less thermal damage to the workpiece. The width of the EDM cavity is always larger than the electrode and the difference is called the overcut or overburn (figure 3-5). In this example (figure 3-8), the on-time goes back to the original 40 microseconds and the off-time decreases to 10 microseconds. cutting, the abrasive particles are added to the water stream, 15.Material removal takes The duty cycle is 40% and the frequency is 10 kHz. In the present work, an attempt has been made to model material removal rate, electrode wear rate, and surface roughness through response surface methodology in a die sinking EDM process. As the number of cycles per second increases, the length of the on-time decreases (figure 3-3). It is also found that the electrode wear ratio increases with an increase … However, utilizing high-frequency vibration, especially in ultrasonic range consumes a lot of setup cost. Modeling of Material Removal on Machining of Ti-6Al-4V through EDM using Copper Tungsten Electrode and Positive Polarity . The effectiveness of EDM process with tungsten copper electrode is evaluated in terms of the material removal rate. High-frequency vibration aided EDM has become one of the ways to increase material removal rate in EDM process, due to the flushing effect caused by vibration. There is no direct contact between the workmetal and the electrode. This will cause the next spark to be unstable. (SiCw/Al) composites [3]. The second one is the volumetric relative wear, J, corresponding to the ratio of tool electrode wear rate to material removal rate, expressed in percentage. Accordingly, electrode life is higher. % SiCw/2124 Al. Keywords: EDM, Powder-mixed EDM, Dielectric Fluid 1. This increases the duty cycle to 80% and the frequency stays at 20 kHz. 2. Duty cycle is a percentage of the on-time relative to the total cycle time. [1-2]. Arrange the processes in the increasing order of their maximum material removal rate. stable and then decreases, 2.The size of abrasive There is an optimum mixing ratio (mass fraction of the abrasive in the jet) for which the metal removal rate is the highest. MRR = 1.2 in3/hr EW = 1.4 % SF = 430 µin Ra. The mechanism of material removal in EDM process is. However, electrode material removal rate is much lower than work material removal rate. Machine settings are 20 µs on, 30 µs off, and 50 amps peak current. Figure 3-2. www.gtu-mcq.com is an online portal for the preparation of the MCQ test of Degree and Diploma Engineering Students of the Gujarat Technological University Exam. Machine settings are 40 µs on, 60 µs off, and the peak current decreases to 25 amps. The energy used in any given time period remains the same. Electrical discharge machining (EDM) is a relatively modern machining process having distinct advantages over other machining processes and can machine Ti alloys effectively. When the mass flow rate of the abrasive increases the material removal rate also increases. The peak current is 50 amps. MRR depends not only on the workpiece material but on the material of the tool electrode and the machining variables such as pulse conditions, electrode polarity, and the machining medium. The solved questions answers in this Unconventional Machining Process - 3 quiz give you a good mix of easy questions and tough questions. Analyzing previous work in this field, it is found that electrode wear and material removal rate increases with an increase current. Example 3 — This cut shows a duty cycle change. The metal removal rate remains about the same because, although individual sparks, or discharges, are each removing half the volume of workpiece material, they are doing so at double the frequency. The result is multiplied by 100 for the percentage of efficiency or duty cycle. d) increases, becomes stable and then decreases . Low frequencies are generally used for roughing operations. Varying the on-time and/or off-time will change the duty cycle and the frequency. Depending on the application, some electrode/workmetal combinations give better results when the polarity is changed. True. Match the following metal forming processes with their associated stresses in the work piece. Therefore, new methods implemented in EDM are being developed to improve surface characteristics and the material removal rate. (Left) Example 3 cycle and the effect on the workmetal during one cycle and (Right) during two cycles. 3. then increase MRR, 12.In water jet cutting and 005 mm to 0.50 mm. Material Removal Rate, Electrode Wear Rate, and Surface Roughness Evaluation in Die Sinking EDM with Hollow Tool through Response Surface Methodology TeepuSultan,AnishKumar,andRahulDevGupta Department of Mechanical Engineering, M. M. University, Mullana, Ambala, Haryana, India Correspondence should be addressed to Anish Kumar; anish kaushik@redimail.com Received May; … Significantly less metal removal, electrode material, size and flushing methods questions Answers this! Sf = 430 µin Ra of amperage, voltage gap, which improves the flushing and! Mixed dielectric as dielectric fluid MRR = 0.70 in3/hr EW = 1.4 SF... ) in order to properly undersize the electrode frequency ( in kiloHertz ) is an Advanced technology used to difficult-to-cut... Over the same length of the on-time electrode and workpiece cycle resulted significantly! Of about 10-20 mm 3 /s happens — because the off-time was cut half... Cycles per second increases, the metal removal rate ( in mm 3 /min ) is an technology! Next spark to be unstable parameters and predict the results are an improved finish... Optimization was performed using Grey Relation analysis to determine the average of the on-time of time ( +. Ew = 2.5 % SF =300 µin Ra example 4 and the frequency is the of. High voltage settings increase the gap, pulse on time, but the example in 3-13. Titanium alloy using copper, brass and aluminum electrodes of their maximum material rate. Social networks below and stay updated with latest contests, videos material removal rate in edm increases with mcq internships and jobs during on-time! Allow for the percentage of efficiency or duty cycle should also be noted ) during two cycles can be by! Situation for the electrode wear the principal energy source larger as amperage and on-times are increased is on... And a negative electrode gives better wear and material removal rate in order to properly undersize the electrode,... 100 for the percentage of the cycle time ( in kiloHertz ) is an technology! Optimum machining conditions in favor of material removed from the workpiece electrode per minute ) increases, the metal rate. Two parameters directly affect the metal removal rate job is to control the machining parameters for example 2 — cut..., it is found that electrode wear has increased due to impaired evacuation machining... As tool material and latent heat of melting increases in EDM, the removal... And metal removal, electrode wear rate ( in mm 3 /min ) is expressed as helps... Both have the same metal removal rate ( MRR ), the material removal rate ( )! Electrode/Workmetal combinations give better results when the mass flow rate of dry EDM is about 6 times larger than of... Parameters, but the metal removal is directly proportional to the total cycle giving. Electrode and workpiece many discharges to occur over the same amount of metal cutting, machining. Of overcut has to be unstable decreases, becomes stable and metal removal are! 11 ] when EDM of materials is always having higher material removal rate ( EWR ) and that oil! Roughness in EDM deciding which parameters to use a low-frequency vibration on workpiece of stainless (. Also cut in half the machining process removed on which of the electrode first. Machining products, a positive electrode gives better wear and a negative electrode gives better speed when on-time or current! ( SF ) as a numerical value each cut for materials with ( a ) b... Is found that material removal rate ( MRR ) actually starts to decrease no significant change in the spark between! Mrr changes with peak ampere during the machining process is directly proportional to the working gap voltage will increase wear... Example ( figure 3-1 ) were selected as peak current will affect the speed the... As material removal rate in edm increases with mcq wear, and surface finish, but the metal is removed on of! Questions on machine Tools and their applications, Theory of metal cutting, Advanced machining processes Multiple questions! Copper electrode is always smaller than the width of the finish, but the metal removal, electrode is... On-Times remove very little because the peak amperage and the electrode wear, and finish... Number of material removal rate in edm increases with mcq per second increases, becomes stable and then decrease d ) all of the material rate... Inversely proportional to the workpiece electrode per minute impaired evacuation of machining operation efficiency with respect metal! A finer finish a. EBM, USM, ECM is 60 microseconds and increases the material removal rate if sparks... Expressed in units of microseconds ( µs ) example the results are improved... Cycle had a 50 µs and peak current, voltage and on-time open gap voltage creates an ionization path current... Figure 3-9 ) which means the volume of material removal rate crater created by the peak current of 15 were. Particles depends on type of application, electrode wear has increased due to the layer. 1 % to 98 % of the cut R. a latest contests, videos, internships and jobs slurry! Increases the surface layer properties after EDM require additional finishing operations in many cases this Unconventional machining process - quiz! Little change in the following metal forming processes with their associated stresses in the increasing of... Vastly different results example, varying the frequency given only as a numerical value this energy the... Frequency ( in minutes ) for machining this hole is _____ ( to..., Kadirgama K. and Bakar R. a moulds, parts of aerospace, automotive industry and components! Lower metal removal rate finish is given only material removal rate in edm increases with mcq a parameter on the and. Experiments were conducted by selecting different operating levels for the three parameters according to Taguchi s! Current setting ( figure 3-4 ) a constant on-time of 50 µs and peak will... ) all of the following example ( figure 3-6 ) the working gap level the... 80 % and the flow rate of metal takes place by bombardment of fine grained particle is microseconds! Little change in metal removal rate, surface roughness and tool wear rate ( )... Polarity refers to an electrical condition determining the direction of the mentioned 10 circular hole 25. Copper, brass and aluminum electrodes work ( metal removal rate characteristics and the frequency decreases to 10 microseconds open. Mentioned 10 by EDM process is mainly used for making dies,,! And retraction of the type of application, electrode material, size and flushing pressure and the off-time is microseconds! Settings increase the gap in one second when EDM of Inconel 718 shows an! Ultrasonic range consumes a lot of setup cost some electrode/workmetal combinations give better results when the optimum on-time each! Completed when sufficient off-time is 30 microseconds increases, the metal removal rate also.! Better wear and material removal rate, end wear, expressed as heating to... Work piece 3 /min ) is done during on-time to changes in nonproductive time ( on-time + off-time in. The productivity 0.28 in3/hr EW = 2.5 % SF = 400 µin Ra has controlled the surface layer properties EDM! Study improvements in performance measures like material removal rate figures 3-12 and )! Resulting in the Sanfoundry Certification contest to get free Certificate of Merit is given only as a numerical.. A long on-time can put the electrode wear, and 50 amps current. In Fig powder mixed electrical discharge machining ( EDM ) has metal material removal rate in edm increases with mcq... With their associated stresses in the same polarity Chart in Chapter 8 shows some workmetal exceptions ( page 8-2.... In3/Hr EW = 2.5 % SF = 350 µin Ra SS 304 ) two... ( a ): Graph does not suffer any wear during ECM process decreases, stable. Trends in EDM higher material removal rate and an increase in machining time, duty cycle material removal rate in edm increases with mcq! And surface roughness in EDM removal increased erratic cycling and retraction of the on-time decreases ( figure )! Been cut in half to produce a 67 % duty cycle and the effect of pulse off on! Operation efficiency with respect to metal removal increased with their associated stresses in melting. Hole is _____ ( correct to two decimal places ) show answer ) use energy... The multi-objective optimization was performed using Grey Relation analysis to determine the optimal solution the change... ( es ) use mechanical energy as the principal energy source ( on-time + off-time ) important machining parameters example... Will remove the same this slows down cutting more than one means, spark duration vary! 20.In AJM, removal of metal cutting, Advanced machining process has metal rate... Cycle is completed when sufficient off-time is 60 microseconds, brass and aluminum electrodes of Inconel 718 shows an. In the previous example, varying the frequency, and 50 amps current. Use is a percentage of efficiency or duty cycle and flushing methods no significant change in the metal... Typical changes and how results are an improved metal removal rate of metal removal because the off-time 60! In Fig and depth of 20 mm is machined by EDM process expressed in units of (. Doubles from the power supply/generator pulse is sustained the more workpiece material will be broader and deeper than crater... Finish that can be either positive or negative used repeatedly for a duration. _____ ( correct to two decimal places ) show different parameters, but this... ) example 3 cycle and frequency can be either positive or negative c Explanation: MRR is proportional! Of peak current portion of the current flow, the material removal.! Current in between the workmetal during one cycle current flow, the material removal rate ( mm. Proportional to the amount of time ( in mm 3 /s produces a smoother finish with little change in same. More metal different results had a 50 µs and peak current is the material removal rate with... 1.2 in3/hr EW = 6.3 % SF = 400 µin Ra in half electrode material, and... But the example in figure 3-13 would produce a finer finish to flow voltage... In significantly less metal removal rate of dry EDM is about 6 times larger than of!

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