scholarly journals Influence of Different Dielectrics on Process Performance for Electrical Discharge-Assisted Milling of Titanium Alloy

Author(s):  
Moran Xu ◽  
Changping Li ◽  
Rendi Kurniawan ◽  
Jielin Chen ◽  
Tae Jo Ko

Abstract Electrical discharge-assisted milling (EDAM) is an effective method for machining titanium alloys according to previous research. In this study, the influence of three different dielectrics (kerosene, EDM oil, and deionized water) on the EDAM performance was studied. Experimental studies reveal the influence of different dielectrics by analyzing the discharged signal, surface morphology, and elemental composition of the electrode. The results show that kerosene and EDM oil have a higher discharge frequency than deionized water. After a long discharge time, carbides and debris were generated during the machining process, which affected the micro-hardness and the discharge stability of the machined material. In EDAM, EDM oil can produce the best surface quality, and the surface roughness value was 34.93%, 87.92%, and 121.68% higher than that of kerosene, deionized water, and conventional milling (CM), respectively.

Author(s):  
Ze Yu ◽  
Dunwen Zuo ◽  
Yuli Sun ◽  
Guohua Li ◽  
Xuemei Chen ◽  
...  

To simultaneously optimize the surface quality and machining efficiency of the electrical discharge machining (EDM) processes used to produce titanium alloy quadrilateral group small hole parts, a combined “EDM + AFM” machining technology is proposed in this paper as an efficient and high-quality machining approach. In the proposed method, TC4 titanium alloy is first machined using the EDM process with graphite electrodes and the abrasive flow machining (AFM) process is then used to finish the machined surface. The effects of various electrical parameters on EDM-derived surface quality and improvements in EDM-derived quality under the application of AFM were assessed and, using the final surface roughness as a constraint condition, the effects of various combinations of EDM and “EDM + AFM” on efficiency were studied. The results revealed that the thickness and surface roughness of the superficial recast layer of the TC4 titanium alloy increase with both current and pulse width; in particular, increasing these parameters can increase the surface roughness by two to three grades. Following AFM, the alloy has a more uniform hardness distribution and the surface stress state changes from tensile to compressive stress, indicating that the combined “EDM + AFM” machining scheme can significantly enhance the surface quality of EDM-produced titanium alloy quadrilateral small group holes. The combined scheme achieves a balancing point beyond which increasing the roughness or the number of machining holes enhances either the machining efficiency or the machining surface quality. In the case of typical titanium alloy quadrilateral group small hole parts, the combined machining process can improve the finishing efficiency and total machining efficiency by 71.2% and 25.36%, respectively.


Author(s):  
Vikas Gohil ◽  
Yogesh M Puri

Electrical discharge turning is a unique form of electrical discharge machining process, which is being especially developed to generate cylindrical forms and helical profiles on the difficult-to-machine materials at both macro and micro levels. A precise submerged rotating spindle as a work holding system was designed and added to a conventional electrical discharge machine to rotate the workpiece. A conductive preshaped strip of copper as a forming tool is fed (reciprocate) continuously against the rotating workpiece; thus, mirror image of the tool is formed on the circumference of the workpiece. The machining performance of electrical discharge turning process is defined and influenced by its machining parameters, which directly affects the quality of the machined component. This study presents an investigation on the effects of the machining parameters, namely, pulse-on time, peak current, gap voltage, spindle speed and flushing pressure, on the material removal rate (MRR) and surface roughness (Ra) in electrical discharge turning of titanium alloy Ti-6Al-4V. This has been done by means of Taguchi’s design of experiment technique. Analysis of variance as well as regression analysis is performed on the experimental data. The signal-to-noise ratio analysis is employed to find the optimal condition. The experimental results indicate that peak current, gap voltage and pulse-on time are the most significant influencing parameters that contribute more than 90% to material removal rate. In the context of Ra, peak current and pulse-on time come up with more than 82% of contribution. Finally, the obtained predicted optimal results were verified experimentally. It was shown that the error values are all less than 6%, confirming the feasibility and effectiveness of the adopted approach.


Author(s):  
M Sreenivasa Rao ◽  
N Venkaiah

Nickel-based alloys are finding a wide range of applications due to their superior properties of maintaining hardness at elevated temperatures, low thermal conductivity and resistance to corrosion. These materials are used in aircraft, power-generation turbines, rocket engines, automobiles, nuclear power and chemical processing plants. Machining of such alloys is difficult using conventional processes. Wire-cut electrical discharge machining is one of the advanced machining processes, which can cut any electrically conductive material irrespective of its hardness. One of the major disadvantages of this process is formation of recast layer as it affects the properties of the machined surfaces. In this study, experimental investigation has been carried out to study the effect of wire-cut electrical discharge machining process parameters on micro-hardness, surface roughness and recast layer while machining Inconel-690 material. Interestingly, hardness of the machined surface was found to be lower than that of the bulk material. The micro-hardness and recast layer thickness are inversely related to the variation of process parameters. Recast layer thickness, surface roughness and hardness of the wire-cut electrical discharge machined surfaces of Inconel-690 are found to be in the range of 10–50 µm, 0.276–3.253 µm and 122–171 HV, respectively, for different conditions. The research findings and the data generated for the first time on hardness and recast layer thickness for Inconel-690 will be useful to the industry.


2016 ◽  
Vol 724 ◽  
pp. 61-65 ◽  
Author(s):  
Ahmad Majdi Abdul-Rani ◽  
Alexis Mouangue Nanimina ◽  
Turnad Lenggo Ginta

This research study was conducted to investigate the effect of nanoaluminum powder mixed electrical discharge machining (PMEDM) on surface morphology and corrosion rate of titanium alloy material. The development of devices such as implants in biomedical engineering application nowadays requires materials having good mechanical and physical properties. Conventional machining process of titanium as implant is a challenge resulting relative poor surface quality. Even using electrical discharge machining (EDM) which is non-conventional machining process there are limitations including machined surface alteration with relative poor machined surface quality, low corrosion resistance and. PMEDM is hypothesized to address the above mentioned problems. In this study, PMEDM on titanium alloy using nanoaluminum powder and copper-tungsten electrode was assessed to investigate the improvement for implant application. Process parameters used are peak-current, ON-time, gap voltage and powder concentration. Surface morphology and average corrosion arte are selected output responses. Results showed that Surface morphology of PMEDM machined surface is significantly improved. PMEDM marginally enhanced corrosion rate of biomedical grade titanium alloy.


2011 ◽  
Vol 130-134 ◽  
pp. 1344-1347
Author(s):  
Wei Jie Chang ◽  
Jian Hua Zhang ◽  
Tao Zhu ◽  
Tao Wang ◽  
Xue Hui Shen

Ultrasonic vibration aided electrical discharge milling in deionized water is proposed and its mechanism is investigated in this paper. The tool electrode is formed to be walled pipe, and high pressure deionized water is supplied through it. Two groups of orthogonal experiments were carried out respectively, one group with ultrasonic vibration on tool electrode and the other without. Research results show that ultrasonic vibration can improve the machining process and surface roughness.


2017 ◽  
Vol 8 (2) ◽  
pp. 179-187 ◽  
Author(s):  
Kankan Ji ◽  
Xingquan Zhang ◽  
Shubao Yang ◽  
Liping Shi ◽  
Shiyi Wang ◽  
...  

Purpose The purpose of this paper is to evaluate surface integrity of quenched steel 1045 ground drily by the brazed cubic boron nitride (CBN) grinding wheel and the black SiC wheel, respectively. Surface integrity, including surface roughness, sub-surface hardness, residual stresses and surface morphology, was investigated in detail, and the surface quality of samples ground by two grinding wheels was compared. Design/methodology/approach In the present work, surface integrity of quenched steel 1045 machined by the CBN grinding wheel and the SiC wheel was investigated systematically. All the specimens were machined with a single pass in the down-cutting mode of dry condition. Surface morphology of the ground specimen was observed by using OLYMPUS BX51M optical microscopy. Surface roughness of seven points was measured by using a surface roughness tester at a cut-off length of 1.8 mm and the measurement traces were perpendicular to the grinding direction. Sub-surface micro-hardness was measured by using HVS-1000 digital micro-hardness tester after the cross-section surface was polished. The residual stress was tested by using X-350A X-ray stress analyzer. Findings When the cut depth is increased from 0.01 to 0.07 mm, the steel surface machined by the CBN wheel remains clear grinding mark, lower roughness, higher micro-hardness and higher magnitude of compressive stress and fine microstructure, while the surface machined by the SiC grinding wheel becomes worse with increasing of cut depth. The value of micro-hardness decreases, and the surface roughness increases, and the surface compressive stress turns into tensile stress. Some micro-cracks and voids occur when the sample is processed by the SiC grinding wheel with cut depth 0.07 mm. Originality/value In this paper, the specimens of quenched steel 1045 were machined by the CBN grinding wheel and the SiC wheel with various cutting depths. The processing quality resulted from the CBN grinding wheel is better than that resulted from the SiC grinding wheel.


2019 ◽  
Vol 889 ◽  
pp. 115-122
Author(s):  
Van Tao Le ◽  
Tien Long Banh ◽  
Xuan Thai Tran ◽  
Nguyen Thi Hong Minh

Electrical discharge machining (EDM) process is widely used to process hard materials in the industry. The process of electrical discharge is changed and called PMEDM when alloy powder is added in the oil dielectric. In the current study, the effect of tungsten carbide alloy powder added in the dielectric on the surface roughness (Ra) and the micro hardness of surface (HV) status of the workpiece SKD61 after machining is investigated. Studies show that the surface roughness and the micro hardness of surface obtained by PMEDM is generally better than that by normal EDM. The method can be applied for improving surface quality such as improving strengthening of molds and machine parts.


2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Nirdesh Ojha ◽  
Florian Zeller ◽  
Claas Mueller ◽  
Holger Reinecke

Electrical discharge machining (EDM) is widely used to manufacture complex shaped dies, molds and critical parts in conductive materials. With the help of an assisting electrode (AE), EDM process can be used to machine nonconductive ceramics. This paper evaluates the mechanical properties of three high-performance nonconductive ceramics (ZrO2, Si3N4, and SiC) that have been machined with the EDM process using AE. Mechanical properties such as Vickers hardness (HV 0.3), surface roughness (Sq), and flexural strength of the machined and the nonmachined samples are compared. The EDM process causes decrease in Vickers hardness, increase in surface roughness, and decrease in flexural strength.


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