scholarly journals Experimental Investigation of a Cryogenically Cooled Oxygen-mist Near-dry Wire-cut Electrical Discharge Machining Process

Author(s):  
Boopathi Sampath ◽  
Sureshkumar Myilsamy

In this paper, a novel method of cryogenically cooled (low-temperature nitrogen gas) wire tool is used during the oxygen-mist near-dry wire-cut electrical discharge machining (NDWEDM) process to cut Inconel 718 alloy material. The current, pulse-width, pulse-interval, and flow rate are the controllable variables for response characteristics, such as the material removal rate (MRR) and wire wear ratio (WWR). The Box-Behnken method is applied to design the experiments to collect the observations from experiments. The mathematical models for each response were developed using significant individual, interaction, and quadratic terms by the sequential sum of the square test. The response surfaces were developed. It was revealed from the analysis that 52.92 % of current, 24.63 % of Pulse-width, 12.81 % of pulse- interval and 5.75 % of flow rate contributed to MRR, while 14.89 % of current, 9.75 % of pulse-width, 62.20 % of pulse-interval, and 5.44 % of flow rate contributed to WWR. The pulse-width has more contribution on MRR due to the long period of spark between the wire and work materials. It was also observed that the pulse-interval has more effect on WWR due to the more ideal period (high spark-pause-time) between two consecutive high-temperature sparks in the wire tool. The wear of the wire tool has been analysed using scanning electron microscopy (SEM) photographs. The desirability principles were first applied to obtain multi-objective solutions with a combination of process parameters to achieve the optimal values of both responses. The predicted combination of results has been validated by data that were collected from confirmation experiments.

Author(s):  
Boopathi Sampath ◽  
Sureshkumar Myilsamy

In this paper, a novel method of cryogenically cooled (low-temperature nitrogen gas) wire tool is used during the oxygen-mist near-dry wire-cut electrical discharge machining (NDWEDM) process to cut Inconel 718 alloy material. The current, pulse-width, pulse-interval, and flow rate are the controllable variables for response characteristics, such as the material removal rate (MRR) and wire wear ratio (WWR). The Box-Behnken method is applied to design the experiments to collect the observations from experiments. The mathematical models for each response were developed using significant individual, interaction, and quadratic terms by the sequential sum of the square test. The response surfaces were developed. It was revealed from the analysis that 52.92 % of current, 24.63 % of Pulse-width, 12.81 % of pulse- interval and 5.75 % of flow rate contributed to MRR, while 14.89 % of current, 9.75 % of pulse-width, 62.20 % of pulse-interval, and 5.44 % of flow rate contributed to WWR. The pulse-width has more contribution on MRR due to the long period of spark between the wire and work materials. It was also observed that the pulse-interval has more effect on WWR due to the more ideal period (high spark-pause-time) between two consecutive high-temperature sparks in the wire tool. The wear of the wire tool has been analysed using scanning electron microscopy (SEM) photographs. The desirability principles were first applied to obtain multi-objective solutions with a combination of process parameters to achieve the optimal values of both responses. The predicted combination of results has been validated by data that were collected from confirmation experiments.


2012 ◽  
Vol 472-475 ◽  
pp. 2013-2017
Author(s):  
Chao Jiang Li ◽  
Yong Feng Guo ◽  
Ji Cheng Bai ◽  
Ze Sheng Lu ◽  
Chuan Chen

The wire electrical discharge machining (WEDM) has been widely used in the field of metal cutting, mold industry, aerospace and so on. However, in the discharge machining, it is very important to restrain the wire-tool vibration for the improvement of machining accuracy. In this paper, it is created a model of the wire vibration with double-ended fixed, established the differential equation of vibration, and derived its full theoretical solution to analysis the vibration factors. Simulations of the wire vibration with ANSYS Transient dynamics analysis were given. An orthogonal design of the wire vibration using L9 orthogonal table was made, and the experiment found that minimize the servo voltage, reduce the pulse width, and select the appropriate wire tension and pulse interval, which can reduce the wire vibration.


Abstract. In this paper, helium-assisted near-dry wire-cut electrical discharge machining (NDWEDM) method molybdenum wire has been used to reduce the environmental impact and to cut M2-HSS material. The pressurized non-reacting helium gas mixed with a small amount of water (Helium-mist) is used as the dielectric fluid to accomplish adequate cooling and flush-out debris. The new experimental setup has been developed to conduct the near-dry WEDM tests using the L9 orthogonal array of the Taguchi technique. The input parameters such as voltage (V), pulse-width (PW), pulse-interval (PI), and flow rate (F) of mixing water and output variables are the material removal rate (MRR) and surface roughness (Ra). It was observed that MRR and Ra are amplified by the rise in voltage and pulse-width, and flow rate conversely, the pulse interval minimizes the responses. The percentage of contribution of pulse width, voltage, pulse interval and flow rate are 24.06%, 32.98%, 12.75% and 30.21% on MRR and 20.94%, 22.22%, 47.86% and 8.97% on Ra respectively. Finally, the confirmation trials have been accomplished to validate the foreseen best parameter sets on optimal responses.


2021 ◽  
Author(s):  
Boopathi Sampath ◽  
Sureshkumar Myilsamy ◽  
Sudhager Sukkasamy

Abstract In this research, the mixing of compressed air with the minimum quantity of water is used as a dielectric medium and the cryogenically cooled molybdenum wire is used as a tool in wire-cut electrical discharge machining (WEDM) to encourage the eco-friendly production, called cryogenically cooled near-dry WEDM process. The nitrogen gas-cooled wire tool is utilized to cut the Inconel 718 alloy workpiece to prevent wire breakage and maintain enough electrical conductivity. The preliminary experiments were conducted to compare wet, dry, near-dry, and cryogenically cooled near-dry WEDM processes. It was revealed that cryogenic cooled near-dry WEDM is better performance than dry, near-dry WEDM except for the wet process. The systematic experiments of eco-friendly cryogenically cooled near-dry WEDM have been conducted to analyse the effect of input factors like spark current, pulse-width, pulse-interval, and mixing water flow rate on material removal rate (MRR) and surface roughness (SR) using Box–Behnken method. The fitted models and response surface graphs were developed to analyse the influences of input factors on each response parameter. It was concluded that MRR and SR of cryogenically cooled near-dry WEDM are increased by maximizing spark current, pulse-width, and flow rate, conversely, both responses were decreased by increasing pulse-interval. The technique for order of preference by similarity to ideal solution (TOPSIS) technique has been applied to predict the best combination of input factors for satisfying the optimal values of both responses.


Author(s):  
Gurpreet Singh ◽  
DR Prajapati ◽  
PS Satsangi

The micro-electrical discharge machining process is hindered by low material removal rate and low surface quality, which bound its capability. The assistance of ultrasonic vibration and magnetic pulling force in micro-electrical discharge machining helps to overcome this limitation and increase the stability of the machining process. In the present research, an attempt has been made on Taguchi based GRA optimization for µEDM assisted with ultrasonic vibration and magnetic pulling force while µEDM of SKD-5 die steel with the tubular copper electrode. The process parameters such as ultrasonic vibration, magnetic pulling force, tool rotation, energy and feed rate have been chosen as process variables. Material removal rate and taper of the feature have been selected as response measures. From the experimental study, it has been found that response output measures have been significantly improved by 18% as compared to non assisted µEDM. The best optimal combination of input parameters for improved performance measures were recorded as machining with ultrasonic vibration (U1), 0.25 kgf of magnetic pulling force (M1), 600 rpm of tool rotation (R2), 3.38 mJ of energy (E3) and 1.5 mm/min of Tool feed rate (F3). The confirmation trail was also carried out for the validation of the results attained by Grey Relational Analysis and confirmed that there is a substantial improvement with both assistance applied simultaneously.


Author(s):  
Sagil James ◽  
Sharadkumar Kakadiya

Shape Memory Alloys are smart materials that tend to remember and return to its original shape when subjected to deformation. These materials find numerous applications in robotics, automotive and biomedical industries. Micromachining of SMAs is often a considerable challenge using conventional machining processes. Micro-Electrical Discharge Machining is a combination of thermal and electrical processes, which can machine any electrically conductive material at micron scale independent of its hardness. It employs dielectric medium such as hydrocarbon oils, deionized water, and kerosene. Using liquid dielectrics has adverse effects on the machined surface causing cracking, white layer deposition, and irregular surface finish. These limitations can be minimized by using a dry dielectric medium such as air or nitrogen gas. This research involves the experimental study of micromachining of Shape Memory Alloys using dry Micro-Electrical Discharge Machining process. The study considers the effect of critical process parameters including discharge voltage and discharge current on the material removal rate and the tool wear rate. A comparison study is performed between the Micro-Electrical Discharge Machining process with using the liquid as well as air as the dielectric medium. In this study, microcavities are successfully machined on shape memory alloys using dry Micro-Electrical Discharge Machining process. The study found that the dry Micro-Electrical Discharge Machining produces a comparatively better surface finish, has lower tool wear and lesser material removal rate compared to the process using the liquid as the dielectric medium. The results of this research could extend the industrial applications of Micro Electrical Discharge Machining processes.


Machines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 69
Author(s):  
Laurenţiu Slătineanu ◽  
Oana Dodun ◽  
Margareta Coteaţă ◽  
Gheorghe Nagîţ ◽  
Irina Beşliu Băncescu ◽  
...  

Wire electrical discharge machining has appeared mainly in response to the need for detachment with sufficiently high accuracy of parts of plate-type workpieces. The improvements introduced later allowed the extension of this machining technology to obtain more complex ruled surfaces with increasingly high requirements regarding the quality of the machined surfaces and the productivity of the wire electrical discharge machining process. Therefore, it was normal for researchers to be interested in developing more and more in-depth investigations into the various aspects of wire electrical discharge machining. These studies focused first on improving the machining equipment, wire electrodes, and the devices used to position the clamping of a wire electrode and workpiece. A second objective pursued was determining the most suitable conditions for developing the machining process for certain proper situations. As output parameters, the machining productivity, the accuracy, and roughness of the machined surfaces, the wear of the wire electrode, and the changes generated in the surface layer obtained by machining were taken into account. There is a large number of scientific papers that have addressed issues related to wire electrical discharge machining. The authors aimed to reveal the aspects that characterize the process, phenomena, performances, and evolution trends specific to the wire electrical discharge machining processes, as they result from scientific works published mainly in the last two decades.


Author(s):  
Omer Eyercioglu ◽  
Kursad Gov

This study presents an experimental investigation of small hole electrical discharge machining of Al-Mg-Ti alloys. A series of drilling operations were carried out for exploring the effect of magnesium content. Holes of 2 mm diameter and 15 mm depth were drilled using tubular single-hole rotary brass electrodes. The rates of material removal and electrode wear, surface roughness, overcut, average recast layer thickness, taper height and angle were studied for Al-Mg-Ti alloys contain 2%, 4%, 6%, 8%, 10%, 12%, and 14% Mg. The results show that the material removal rate is increasing with increasing Mg content while the rate of electrode wear is almost unchanged. Due to decreasing the melting temperature of the Al-Mg-Ti alloy with increasing Mg content, more metal melts and vaporizes during electrical discharge machining drilling. Therefore, more overcut and taper, thicker white layer, and rougher surfaces were measured for higher Mg content.


2011 ◽  
Vol 189-193 ◽  
pp. 4245-4255
Author(s):  
Shi Jin Zhang ◽  
Yu Qiang Wu ◽  
Yan Li Wang

Technological advancement, on the one hand, made Electrical Discharge Machining (EDM) much faster. One example of that is the presence of Wire Electrical Discharge Machining – High Speed (WEDM-HS) machine, which makes the material removal rate as high as 80 . On the other hand, it also made Abrasive Waterjet (AWJ) achieve much better quality surface and tighter tolerance. As a result, these two types of machining process have converged to the point where they can complement one another quite nicely in selected applications. However, it does not mean user may pick any one for their applications. The proper selection not only decreases the manufacturing costs but also achieves better quality. This paper focuses on comparing WEDM-HS with AWJ by actually cutting a special designed sample. Through comparison from several aspects which include dimension precision, surface roughness, cost, cutting time and surface damage, a proper selection guidance for regular user has been provided.


2012 ◽  
Vol 622-623 ◽  
pp. 19-24
Author(s):  
P. Balasubramanian ◽  
Thiyagarajan Senthilvelan

In this study, input parameters of Electrical Discharge machining (EDM) process have been optimised for two different materials EN-8 and Die steel-D3 were machined by using sintered copper electrode. Analysis of variance (ANOVA) was applied to study the influences of process parameters viz: - peak current, pulse on time, di-electric pressure and diameter of electrode on material removal rate (MRR), tool wear rate (TWR) and surface roughness (SR) for both materials. Response surface methodology (RSM) has been applied to optimise the multi responses in order to get maximum MRR, minimum TWR and minimum SR. Furthermore, mathematical model has been formulated to estimate the corresponding output responses for both work pieces. It has been observed that compared to EN 8 material, the MRR value is low and TWR is high for D3 material. However the SR value is marginally lower than obtained in EN8.R2 value is above 0.90 for both work pieces.


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