The effect of magnesium content on drilling of Al-Mg-Ti alloy by hole electrical discharge machining process

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.

ROTASI ◽  
2019 ◽  
Vol 21 (1) ◽  
pp. 1
Author(s):  
Petrus Londa

Electrical Discharge Machining (EDM) adalah non-conventional machining process. EDM dapat memotong semua jenis benda kerja yang bersifat penghantar listrik, terutama digunakan pada benda kerja yang sangat keras dan memiliki bentuk yang rumit, yang tidak dapat dipotong oleh mesin konvensional. Penelitian ini menggunakan metode Taguchi untuk menentukan variabel pemesinan yang secara signifikan mempengaruhi proses pemotongan pada beberapa material elektroda (tembaga, kuningan, alumunium) dan benda kerja dari bahan K460 (amutit S). Taguchi L25 Orthogonal standard arrays dan analysis of variance (ANOVA) dapat menentukan performa variabel pemotongan (PON, POFF, GAP, QDON, SERVO dan LT) dengan variabel yang diteliti adalah Electrode Wear Rate (EWR), Material Removal Rate (MRR) dan Diameter Overcut (DOC). Hasil dari penelitian ini ditampilkan dalam bentuk tabel-tabel dan grafik yang menunjukan variabel pemesinan yang signifikan mempengaruhi proses pemotongan sesuai dengan jenis material elektroda yang digunakan.


Author(s):  
Sanjeev Verma ◽  
PS Satsangi ◽  
KD Chattopadhyay

The application of nonconductive ceramic materials is growing in engineering and manufacturing field due to their properties such as high hardness, low thermal conductivity, and resistance to oxidation. But fabricating structures from such materials are difficult and most of the traditional machining techniques are not appropriate. The electrical discharge machining has become a popular machining process for machining nonconducting oxide and nonoxide ceramics such as alumina, silicon nitrides, SiAlON, and zirconium. In the present study, a technique to machine the nonconductive SiAlON ceramic, having resistivity of the order of 100000 Ω-cm is developed. An assistive electrode technique along with graphite powder mixed specially made dielectric mixture of hydrocarbon fluids was used for the electrical discharge machining process. The experiments were conducted according to the Taguchi design and analysis of variance using signal-to-noise ratios showcasing significant parameters and their optimal values for material removal, electrode wear, and size overcut achieved after electrical discharge machining. For multiparameter optimization, the grey relational analysis was carried out for response parameters with suitable weights. Analysis of variance on the grey relational grade showed discharge current, duty factor, and additive percentage as most significant parameters. As the central aim of this research is material removal, the significant parameters found for material removal rate were further used for response surface methodology and their optimum values as central design values for experimentation. A second-order response model was formulated to estimate the machining performance. To validate the study, confirmation experiments were carried out and predicted results have been found to be in good agreement with experimental findings. Based on the experimental investigations, it can be said that a novel and efficient technique has been developed to machine the high resistivity ceramics. The scanning electron microscopic images confirmed that material is removed mostly by spalling and no significant cracks are visible.


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.


2015 ◽  
Vol 14 (03) ◽  
pp. 189-202 ◽  
Author(s):  
V. Vikram Reddy ◽  
P. Madar Valli ◽  
A. Kumar ◽  
Ch. Sridhar Reddy

In the present work, an investigation has been made into the electrical discharge machining process during machining of precipitation hardening stainless steel PH17-4. Taguchi method is used to formulate the experimental layout, to analyze the effect of each process parameter on machining characteristics and to predict the optimal choice for each electrical discharge machining process parameters namely, peak current, pulse on time and pulse off time that give up optimal process performance characteristics such as material removal rate, surface roughness, tool wear rate and surface hardness. To identify the significance of parameters on measured response, the analysis of variance has been done. It is found that parameters peak current and pulse on time have the significant affect on material removal rate, surface roughness, tool wear rate and surface hardness. However, parameter pulse off time has significant affect on material removal rate. Confirmation tests are conducted at their respective optimum parametric settings to verify the predicted optimal values of performance characteristics.


Author(s):  
R Rajeswari ◽  
MS Shunmugam

Electrical discharge machining is used in the machining of complicated shapes in hardened molds and dies. In rough die-sinking stage, attempts are made to enhance material removal rate with a consequential reduction in cycle time. Powder mix and ultrasonic assistance are employed in the electrical discharge machining process to create gap conditions favoring material removal. In the present work, experiments are carried out on hardened D3 die steel using full-factorial design based on three levels of voltage, current and pulse on time. The gap phenomena in graphite powder-mixed and ultrasonic-assisted rough electrical discharge machining are studied using a detailed analysis of pulse shapes and their characteristic trains. Two new parameters, namely, energy expended over a second ( E) and performance factor ( PF) denoting the ratio of energy associated with sparks to total discharge energy, bring out gap conditions effectively. In comparison with the conventional electrical discharge machining for the selected condition, it is seen that the graphite powder mixed in the dielectric enhances the material removal rate by 20.8% with E of 215 J and PF of 0.227, while these values are 179.8 J and 0.076 for ultrasonic-assisted electrical discharge machining with marginal reduction of 3.9%. Cross-sectional images of workpieces also reveal the influence of electrical discharge machining conditions on the machined surface. The proposed approach can be extended to different powder mix and ultrasonic conditions to identify condition favoring higher material removal.


Author(s):  
Sadananda Chakraborty ◽  
Souren Mitra ◽  
Dipankar Bose

Precision machining characteristics with high-dimensional accuracy make the material more adaptable towards the applications. The present study employs the powder mixed wire electrical discharge machining process to machine Ti6Al4V alloy material. In spite of limited drawbacks and enhanced output in the powder mixed wire electrical discharge machining process, the present problem has been formulated for improving the machining efficiency of Ti6Al4V. The impact of suspended powder characteristics on responses, that is, material removal rate and surface roughness, is examined throughout the process. The current investigation also focuses on the interaction effect of machining constraints along with Al2O3 abrasive mixed dielectric to achieve economical machining output for the Ti6Al4V material. An effort has been presented to obtain optimal solutions using the different methodologies, namely response surface methodology, grey relation analysis, and particle swarm optimization. The study reveals that discharge energy is deeply influenced by the peak current and pulse off time followed by powder concentration in the powder mixed wire electrical discharge machining process. The maximum material removal rate of 6.628 mm3/min and average surface finish of 1.386 μm are the outcome of the present study for a set of optimal machining settings, that is, pulse off time ( Toff) of 7.247 μs, pulse on time ( Ton) of 30 μs, peak current ( Ip) of 2 A, and powder concentration of 4 g/L. Finally, the proposed model has been verified that the hybrid particle swarm optimization technique has the highest adequate capability to achieve maximum output. Thus, the approach offered an enhancement on performance measures of Ti6Al4V alloy in the powder mixed wire electrical discharge machining process.


2014 ◽  
Vol 941-944 ◽  
pp. 2127-2133 ◽  
Author(s):  
Nirdesh Ojha ◽  
Florian Zeller ◽  
Claas Mueller ◽  
Holger Reinecke

The ability to machine advanced ceramic materials such as ZrO2, SiC, and AlN is of high interest for various industries because of the extraordinary material properties that these ceramics possess. Once sintered, these ceramics are characterized with high mechanical strength, high thermal stability and high chemical inertness. Therefore it is extremely difficult to machine these ceramics with dimensions in few microns using traditional techniques. Electrical discharge machining (EDM) is an electro-thermal machining process used to structure conductive materials. By applying a conductive layer on top of the non-conductive material, the EDM process can also be used to machine the non-conductive material. This paper presents a study on the effect of tool polarity and tool rotation on the material removal rate and electrode wear ratio during the EDM process of non-conductive SiC, ZrO2 and AlN ceramics. The reasons for the variation in the material removal rates among the different ceramics are examined by comparing the material properties. Relatively lower value of flexural strength, fracture toughness and melting temperature is the reason for AlN ceramic to have the higher MRR than SiC and ZrO2 ceramics.


2009 ◽  
Vol 83-86 ◽  
pp. 672-679 ◽  
Author(s):  
Suleiman Abdulkareem ◽  
Ahsan Ali Khan ◽  
Mohamed Konneh

In electrical discharge machining (EDM), material is removed by a series of electrical discharge between the electrode (tool) and the workpiece that develops a temperature of about 8,0000C to 12,0000C. Due to high temperature of the sparks, work material is melted and vapourized, at the same time the electrode material is also eroded by melting and vapourization. Electrodes wear (EW) process is quite similar to the material removal mechanism as the electrode and the workpiece are considered as a set of electrode in EDM. In the present study effort has been made to reduce EW by cooling, using liquid nitrogen during the EDM of titanium alloy. Investigation on the effect of cooling on electrode wear (EW), material removal rate (MRR) and surface roughness (Ra) of the workpiece was carried out. Current (I), pulse on-time (ton), pause off-time (toff) and voltage (v) were considered as the machining parameters. Design of experiment (DOE) was used to design the experimental works. Cooling of electrode by this technique reduced the melting and vapourization of electrode material and enhances electrode life. It was possible to reduce EW up to 27% by applying this technique while MRR and Ra were improved by 18% and 8% respectively.


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