scholarly journals Improving micro-hardness of stainless steel through powder-mixed electrical discharge machining

2014 ◽  
Vol 228 (18) ◽  
pp. 3374-3380 ◽  
Author(s):  
Zakaria Mohd Zain ◽  
Mohammed Baba Ndaliman ◽  
Ahsan Ali Khan ◽  
Mohammad Yeakub Ali
Keyword(s):  
Stainless Steel ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Tantalum Carbide ◽  
Dielectric Fluid ◽  
Micro Hardness ◽  
Machined Surface ◽  
Surface Machining ◽  
Pulse On Time ◽  
Pulse Off Time

Powder-mixed electrical discharge machining (PMEDM) is the technique of using dielectric fluid mixed with various types of powders to improve the machined surface output. This process is fast gaining prominence in electrical discharge machining (EDM) industry. The objective of this investigation is to determine the ability of tantalum carbide (TaC) powder-mixed dielectric fluid to enhance the surface properties of stainless steel material during EDM. The properties investigated are the micro-hardness and corrosion characteristics of the EDMed surface. Machining was conducted with 25.0 g/L concentration of TaC powder in kerosene dielectric fluid. The machining variables used were the peak current, pulse on time and the pulse off time. The effects of these variables on the micro-hardness of the EDMed surface were determined. Corrosion tests were also conducted on the samples that exhibited higher hardness. Results showed that the EDMed surface was alloyed with elements from the TaC powder. The highest micro-hardness obtained with PMEDM is about 1,200 Hv. This is about 1.5 times that obtained without TaC powder in the dielectric fluid. The loss in weight during corrosion test was found to be 0.056 µg/min for the PMEDM which was much lower than the lowest value of 10.56 µg/min obtained for the EDM without powder dielectric fluid.

Optimization of machining parameters in chromium-additive mixed electrical discharge machining of the AA7075/5%B4C composite

2021 ◽  
pp. 095440892110317
Author(s):  
Vineet Dubey ◽  
Anuj K Sharma ◽  
Balbir Singh
Keyword(s):  
Surface Roughness ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Process Condition ◽  
Dielectric Fluid ◽  
Optimum Process ◽  
Machining Parameters ◽  
Machined Surface ◽  
Pulse On Time ◽  
Pulse Off Time

The present study establishes the optimum process condition for additive mixed electrical discharge machining of Al7075–5%B4Cp metal matrix composite by performing experimental investigation. The suspension of chromium particles in a dielectric fluid is used as an additive. The input process parameters selected for experimentation are specifically pulse on-time, gap voltage, pulse off-time and peak current, for analysing their influence on wear of the tool along with surface roughness of the composite. Comparative study of the machined surface is done by analysing microstructures, cracks and recast layers formed at different settings of input parameters using a scanning electron microscope. Rise in amount of current and pulse on-time led to increased height of the recast layer generated on the surface of the machined workpiece. Furthermore, a confirmatory experiment was performed at the optimal setting. The result revealed an error of 5.5% and 7.5% between experimental and predicted value of tool wear rate and surface roughness.

Simultaneous Improvement of Micro-Hardness and Surface Finish in Die Steels by Powder-Mixed EDM Process

2014 ◽  
Author(s):  
Sanjeev Kumar
Keyword(s):  
Surface Finish ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Dielectric Medium ◽  
Micro Hardness ◽  
Machined Surface ◽  
Die Steels ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time

Electrical Discharge Machining (EDM) is widely used by the die and tool making industry for the accurate machining of complex internal profiles in various types of dies. Due to the absence of physical contact between the tool and the workpiece, the hardness of the workpiece is not a consideration in this process and die steels can be machined after hardening. Although EDM is a machining process, it has also been successfully used for improving the surface properties of dies and press tools. The intrinsic nature or the process causes some dissolution of the electrode and these particles may alloy with the machined surface under appropriate machining conditions. Breakdown of the hydrocarbon dielectric under intense heat of the spark contributes carbon to the plasma channel. Another method to produce similar alloying effect is the addition of powders of the desirable elements in the dielectric medium. If such powders are conductive in nature, they affect the energy distribution and sparking efficiency and consequently, the surface finish and micro-hardness. This paper presents the results of an experimental study into electrical discharge machining of H13 hot die steel with graphite powder mixed in the dielectric medium. Copper electrode and kerosene dielectric were used for the experiments and three operating parameters, namely peak current, pulse on-time and pulse off-time were varied. Results show increase in micro-hardness by 42% and improvement in surface finish by 68%. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analysis show smooth surface devoid of any craters and significant presence of carbon in the machined surface which is expected to provide self-lubricating properties to the die surface. Chemical composition of the machined surface checked with an optical emission spectrometer shows increase in percentage of carbon from 0.44% to 3.23%. All three operating parameters emerge as significant and the favorable machining conditions for surface alloying are found to be low value of peak current, shorter pulse on-time, longer pulse off-time and negative polarity of the tool electrode.

scholarly journals Parametric optimization of wire cut electrical discharge machining

2014 ◽  
Vol 3 (2) ◽  
pp. 212
Author(s):  
M. Durairaj ◽  
A.K.S. Ansari ◽  
M. H. Gauthamkumar
Keyword(s):  
Surface Roughness ◽  
Orthogonal Array ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Fluid Pressure ◽  
Performance Criteria ◽  
Dielectric Fluid ◽  
Machining Parameters ◽  
Pulse On Time ◽  
Pulse Off Time

Wire Electrical Discharge Machining is a manufacturing process whereby a desired shape is obtained using electrical discharges (or) by repetitive spark cycle. Precision and intricate machining are the strengths. Machining parameters tables provided by the machine tool manufacturers often do not meet the operator requirements. Selection of optimum machining and machining parameters combinations is needed for obtaining higher cutting efficiency and accuracy. In this present study, machining is done using Wire-Cut EDM and optimization of surface roughness is done using Taguchis design of experiments. Experimentation was planned as per Taguchis L16 orthogonal array. Each experiment has been performed under different cutting conditions of gap voltage, pulse ON time, and pulse OFF time and Wire feed. Dielectric fluid pressure, wire speed, wire tension, resistance and cutting length are taken as fixed parameters. Inconel 800 was selected as a work material to conduct the experiments. From experimental results, the surface roughness was determined for each machining performance criteria. Signal to noise ratio was applied to measure the performance characteristics deviating from the actual value. Finally, experimental confirmation was carried out to identify the effectiveness of this proposed method. Keywords: Optimization; Taguchis L-16 Orthogonal Array; Surface Roughness; S/N Ratio.

Influence of Pulse-on-Time on the Performance of Wire Electrical Discharge Machining of Ti-6Al-4V Using Zinc Coated Brass Wire

2014 ◽  
Vol 592-594 ◽  
pp. 416-420 ◽  
Author(s):  
Singaravelu D. Lenin ◽  
A. Uthirapathi ◽  
Ramana Reddy P.S. Venkata ◽  
Muthukannan Durai Selvam
Keyword(s):  
Surface Roughness ◽  
Electrical Discharge ◽  
Metal Removal ◽  
Electrical Discharge Machining ◽  
Kerf Width ◽  
Dielectric Fluid ◽  
Wire Electrical Discharge Machining ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Brass Wire

The present paper describes the influence of pulse-on-time on performance features such as Metal Removal Rate (MRR), Kerf width, Surface Roughness (SR) on cutting Titanium alloy (Ti-6Al-4V) in wire electrical discharge machining (WEDM) using zinc coated brass wire. The deionised water is used as dielectric fluid. The process parameters such as wire tension, wire speed, flushing pressure, discharge current, sparking voltage and pulse off time have kept constant at appropriate values throughout the experiment and the pulse on time is varied at nine different intervals. It was found that pulse-on-time is the most significant factor which greatly influences MRR, kerf width, and SR. It was also observed that taper at the end of cutting zone which is unavoidable occurrence for the machined part. This is due to the erosion of wire material. The surface roughness increases with increase in pulse on time also with higher rate of MRR.

Surface Study in a Non-conventional (Electrical Discharge Machining) Process for Grade 6 Titanium Material

2014 ◽  
Vol 68 (1) ◽  
Author(s):  
Md. Ashikur Rahman Khan ◽  
M. M. Rahman
Keyword(s):  
Surface Roughness ◽  
Process Parameters ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Machining Process ◽  
Machined Surface ◽  
Titanium Material ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time

Electrical discharge machining (EDM) produces complex shapes and permits high-precision machining of any hard or difficult-to-cut materials. The performance characteristics such as surface roughness and microstructure of the machined face are influenced by numerous parameters. The selection of parameters becomes complicated. Thus, the surface roughness (Ra) and microstructure of the machined surface in EDM on Grade 6 titanium alloy are studied is this study. The experimental work is performed using copper as electrode material. The polarity of the electrode is maintained as negative. The process parameters taken into account in this study are peak current (Ip), pulse-on time (Ton), pulse-off time (Toff), and servo-voltage (Sv). A smooth surface finish is found at low pulse current, small on-time and high off-time. The servo-voltage affects the roughness diversely however, a finish surface is found at 80 V Sv. Craters, cracks and globules of debris are appeared in the microstructure of the machined part. The size and degree of craters as well as cracks increase with increasing in energy level. Low discharge energy yields an even surface. This approach helps in selecting proper process parameters resulting in economic EDM machining. 

scholarly journals Parametric Optimization and Effect of Nano-Graphene Mixed Dielectric Fluid on Performance of Wire Electrical Discharge Machining Process of Ni55.8Ti Shape Memory Alloy

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2533
Author(s):  
Rakesh Chaudhari ◽  
Jay Vora ◽  
L.N.López de Lacalle ◽  
Sakshum Khanna ◽  
Vivek K. Patel ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Machining Process ◽  
Dielectric Fluid ◽  
Wire Electrical Discharge Machining ◽  
Nano Graphene ◽  
Pulse On Time ◽  
Pulse Off Time

In the current scenario of manufacturing competitiveness, it is a requirement that new technologies are implemented in order to overcome the challenges of achieving component accuracy, high quality, acceptable surface finish, an increase in the production rate, and enhanced product life with a reduced environmental impact. Along with these conventional challenges, the machining of newly developed smart materials, such as shape memory alloys, also require inputs of intelligent machining strategies. Wire electrical discharge machining (WEDM) is one of the non-traditional machining methods which is independent of the mechanical properties of the work sample and is best suited for machining nitinol shape memory alloys. Nano powder-mixed dielectric fluid for the WEDM process is one of the ways of improving the process capabilities. In the current study, Taguchi’s L16 orthogonal array was implemented to perform the experiments. Current, pulse-on time, pulse-off time, and nano-graphene powder concentration were selected as input process parameters, with material removal rate (MRR) and surface roughness (SR) as output machining characteristics for investigations. The heat transfer search (HTS) algorithm was implemented for obtaining optimal combinations of input parameters for MRR and SR. Single objective optimization showed a maximum MRR of 1.55 mm3/s, and minimum SR of 2.68 µm. The Pareto curve was generated which gives the optimal non-dominant solutions.

scholarly journals Optimization and modeling of Electrical Discharge parameters on Machining of Stavax Steel

2020 ◽  
Vol 6 (11) ◽  
pp. 53-62
Author(s):  
P Srinivasa Rao and Prof. Eshwara Prasad Koorapati
Keyword(s):  
Discharge Current ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Linear Regression Analysis ◽  
Performance Characteristics ◽  
Dielectric Fluid ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time

This work focuses on the use of the Taguchi method in order to find out the optimized parameters of the process like discharge current, pulse on time and pulse off time on the machining features such as material removal rate(MRR), surface roughness(SR) & tool wear rate(TWR) on Stavax Steel by means of Electrical Discharge Machining(EDM). It is also intended to study the individual influence of parameters on the performance characteristics. The dielectric fluid circulating system is modified to conduct the experiments. The analysis of variance (ANOVA) is made to recognise the importance of parameters on the response. By using non-linear regression analysis the empirical models are developed in order to predict these performance characteristics and the confirmation test was conducted at the optimal parameters settings to check the optimum expected values of performance features. Detailed analysis by using ANOVA is done and came out with the findings as a pulse on time is the most significant process parameter, next is the discharge current and the insignificant parameter is the pulse off time. Machining surface morphology was studied and observed that crater size is large and deeper due to a large amount of metal is melted and vaporized at the optimum condition of MRR.

Investigation on effect of process parameter on surface integrity during electrical discharge machining of NiTi 60

2020 ◽  
Vol 16 (6) ◽  
pp. 1385-1394
Author(s):  
Mahendra Uttam Gaikwad ◽  
A. Krishnamoorthy ◽  
Vijaykumar S. Jatti
Keyword(s):  
Surface Integrity ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
White Layer ◽  
Hardness Test ◽  
Machined Surface ◽  
Content Type ◽  
Pulse On Time ◽  
Pulse Off Time

PurposeElectrical discharge machining (EDM) of hard materials like NiTi 60 alloys is important as it finds application in different sectors of engineering such as automobile, aircraft, biomedical, oil industries, etc.Design/methodology/approachThe first target of this investigation is to determine the effect of process parameters such as current, voltage, pulse on time and pulse off time on the material removal rate (MRR), surface roughness (SR) and white layer formation (WLT) for NiTi 60 smart material alloy. The secondary aim is to identify the presence of surface integrity parameters such as cracks, WLT, microvoids, globules and debris formation by using the scanning electron microscopy technique and with the use of ImageJ software for die sink EDM machining of NiTi 60 alloy.FindingsThe results reveal that current is significant for MRR, voltage and current influence SR, and for WLT, voltage is a significant factor. The experimentation study also shows the generation of oxide and carbide layers on the machined surface, which were evident with the use of the X-ray diffraction technique. The presence of these oxide and carbide layers causes to form WLT on the machined surface and thereby increases the hardness of the machined surface.Originality/valueHardness test was performed with Vickers hardness tester, which gives evidence for the increase in hardness of machined surface due to the generation of WLT.

Optimization and surface modification in electrical discharge machining of AA 6061/SiCp composite using Cu–W electrode

2015 ◽  
Vol 231 (3) ◽  
pp. 332-348 ◽  
Author(s):  
Balbir Singh ◽  
Jatinder Kumar ◽  
Sudhir Kumar
Keyword(s):  
Process Parameters ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Surface Characteristics ◽  
Electrode Wear ◽  
Material Transfer ◽  
Machined Surface ◽  
Recast Layer Thickness ◽  
Pulse On Time ◽  
Pulse Off Time

This paper presents the experimental investigation on the electro-discharge machining of aluminum alloy 6061 reinforced with SiC particles using sintered Cu–W electrode. Experiments have been designed as per central composite rotatable design, using response surface methodology. Machining characteristics such as material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR) have been investigated under the influence of four electrical process parameters; namely peak current, pulse on time, pulse off time, and gap voltage. The process parameters have been optimized to obtain optimal combination of MRR, EWR, and SR. Further, the influence of sintered Cu–W electrode on surface characteristics has been analyzed with scanning electron microscopy, energy dispersive spectroscopy, and Vicker microhardness tests. The results revealed that all the process parameters significantly affect MRR, EWR, and SR. The machined surface properties are modified as a result of material transfer from the electrode. The recast layer thickness is increased at higher setting of electrical parameters. The hardness across the machined surface is also increased by the use of sintered Cu–W electrode.

Mathematical Modeling of Machining Parameters in Electrical Discharge Machining with Cu-B4C Composite Electrode

2012 ◽  
Vol 488-489 ◽  
pp. 871-875
Author(s):  
V. Anandakrishnan ◽  
V. Senthilkumar
Keyword(s):  
Mathematical Models ◽  
Current Pulse ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Machining Parameters ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time ◽  
Selection Of

Copper based metal matrix composite reinforced with Boron Carbide is a newly developed Electrical Discharge Machining (EDM) electrode showing better performance than the conventional copper based electrode. Right selection of machining parameters such as current, pulse on time and pulse off time is one of the most important aspects in EDM. In this paper an attempt has been made to develop mathematical models for relating the Material Removal Rate (MRR), Tool Removal Rate (TRR) and Surface roughness (Ra) to machining parameters (current, pulse-on time and pulse-off time). Furthermore, a study was carried out to analyze thSubscript texte effects of machining parameters on various performance parameters such as, MRR, TRR and Ra. The results of Analysis of Variance (ANOVA) indicate that the proposed mathematical models, can adequately describe the performance within the limits of the factors being studied. Response surface modeling is used to develop surface and contour graphs to analyze the effects of EDM input parameters on outer parameters.

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