Investigating the Micro-EDM Machinability of Bulk Metallic Glass in Micro-EDM Drilling

Author(s):  
Chong Liu ◽  
Asif Rashid ◽  
Muhammad P. Jahan ◽  
Jianfeng Ma

Abstract Bulk Metallic Glass (BMG) is a solid metallic material with disordered atomic structure, that has the characteristics of high elasticity, hardness, fracture toughness, and superior corrosion resistance. High aspect ratio micro-through holes on BMG has prospective applications in space, nuclear reactor, thermodynamics engineering, biomedical, and electronics industries. In this study, the micro-EDM machinability of BMG (Vit 1b: Zr67Cu10.6Ni9.8Ti8.8Be3.8 (wt%)) is evaluated. The micro-EDM machinability of BMG has been assessed based on the volume of material removal rate (MRR), tool wear rate (TWR), micro-hole surface quality, and dimensional accuracy. The effect of various electrical and non-electrical parameters is studied. It is found that micro-EDM is capable producing high aspect ratio micro-holes on difficult-to-machine BMG. The deposition of resolidified debris around the edge of the micro-holes, both at the entrance and exit side, are found to be a common phenomenon in micro-EDM of BMG. The reduction of capacitance was found to be the effective way for reducing the resolidified debris around the edges. Capacitance was found to be have more pronounced effect, with gap voltage having little effect on the quality of micro-holes. The electrode rotational speed had insignificant effect on the quality of micro-holes. In terms of dimensional accuracy, which was measured by overcut and taper angle, both the gap voltage and electrode rotational speed had little effect. The lower electrode rpm was found to reduce the taperness of the micro-holes, although the material removal rate decreases and tool wear rate increases. Finally, analysis of the composition of tool electrode before and after machining indicates the migration of materials from the dielectric and workpiece to the tool electrode and vice versa.

Author(s):  
Shivraj Yeole ◽  
Nagabhushana Ramesh Nunna ◽  
Balu Naik Banoth ◽  
Ramya Alluru

The Micro-Electrical Discharge Machining, popularly known as micro-EDM, is a nonconventional machining process mainly used for producing micro features like micro holes, micro gears, micro moulds etc. that are difficult to be obtained by conventional process. It can machine different types of conductive materials especially the ones which are difficult to cut and machine. Microholes have been drilled using micro-EDM process on various alloys like Ti-6Al-4V, Inconel 718 etc. using electrodes like Copper, Tungsten etc. The parts produced by micro-EDM are widely used in micro-electro-mechanical systems (MEMS), biomedical applications, automotive industry, and defence industry. Selection and use of correct process parameters is of paramount importance for achieving superior surface quality and higher machining rates while performing micro drilling. However, this process has been characterized by low tool wear rate, low machining rate and longer machining time as compared to other non-conventional processes. This paper aims at studying the influence of various process parameters while drilling micro holes on Maraging Steel 300 alloy using a brass electrode. Maraging Steel 300 alloy is widely used in aerospace, tooling and machinery applications. Brass was selected as the electrode material so as to know its influence in the microdrilling process as it is known for achieving high material removal rate along with high wear ratio. Machining parameters considered in this work were pulse on time, pulse off time, tool diameter and current. A total of 27 micro holes of 300 μm, 400 μm and 500 μm were drilled on Maraging Steel 300 alloy as per the orthogonal array design based Taguchi methodology. Experiments were carried out on Toolcraft V04056 micro-EDM machine. Dielectric used was distilled water. The output responses observed were material removal rate, tool wear rate and overcut. Analysis was carried out using signal to noise ratio analysis. Material removal rate, tool wear rate and overcut were found to be influenced mainly by pulse on time and current. In order to know and better understand the surface morphology of the micro-holes, SEM micro-graphs were obtained. Presence of spatters and re-deposited eroded material were observed in few of the drilled micro holes. The results were verified by performing confirmation experiment at the obtained optimum combination. The confirmation results were in close proximity to the predicted results.


2011 ◽  
Vol 314-316 ◽  
pp. 1811-1817 ◽  
Author(s):  
Samykano Mahendran ◽  
Ismail Fazli ◽  
Sawalingam Thinesh Chander

The development of new, advanced engineering materials and the need for precise flexible prototypes and low volume production have made Micro-EDM and important manufacturing process to meet such demands. The most important parameters in Micro-EDM are the material removal rate (MRR), the tool wear rate (TWR), accuracy and surface texture. The influence of peak current, gap voltage, pulse duration and process parameters plays important role in determining the material removal rate and tool wear rate on Micro EDM. Thus, this paper describes the development of the Micro-EDM based on the tool wear rate and material removal rate of the system using directly mounted APA 400MML actuator as the tool feed control system.


2016 ◽  
Vol 40 (3) ◽  
pp. 331-349 ◽  
Author(s):  
S. Sivasankar ◽  
R. Jeyapaul

This research work concentrates on Electrical Discharge Machining (EDM) performance evaluation of ZrB2- SiC ceramic matrix composites with different tool materials at various machining parameters. Monolithic ZrB2 possesses lower relative density (98.72%) than composites. ZrB2 with 20 Vol.% of SiC possesses 99.74% of the relative density with improved hardness values. Bend strength and Young’s modulus increase with SiC addition until it reaches 20 Vol% and then decreasing. EDM performance on tool materials of tungsten, niobium, tantalum, graphite and titanium at various levels of pulse on time and pulse off time are analyzed. Graphite produces the best Material removal rate (MRR) for all the workpieces. Tool wear rate decreases with melting point and thermal conductivity of the tool material.


Author(s):  
Arun Kumar Rouniyar ◽  
Pragya Shandilya

Magnetic field assisted powder mixed electrical discharge machining is a hybrid machining process with suitable modification in electrical discharge machining combining the use of magnetic field and fine powder in the dielectric fluid. Aluminum 6061 alloy has found highly significance for the advanced industries like automotive, aerospace, electrical, marine, food processing and chemical due to good corrosion resistance, high strength-to-weight ratio, ease of weldability. In this present work, magnetic field assisted powder mixed electrical discharge machining setup was fabricated and experiments were performed using one factor at a time approach for aluminum 6061 alloy. The individual effect of machining parameters namely, peak current, pulse on time, pulse off time, powder concentration and magnetic field on material removal rate and tool wear rate was investigated. The effect of peak current was found to be dominant on material removal rate and tool wear rate followed by pulse on time, powder concentration and magnetic field. Increase in material removal rate and tool wear rate was observed with increase in peak current, pulse on time and a decrease in pulse off time, whereas, for material removal rate increases and tool wear rate decreases up to the certain value and follow the reverse trend with an increase in powder concentration. Material removal rate was increased and tool wear rate was decreased with increase in magnetic field.


Author(s):  
Shivraj Yeole ◽  
Nagabhushana Ramesh Nunna ◽  
Balu Naik Banoth

Electrical Discharge Micro Drilling (EDMD) is considered as one of the most effective method for machining difficult to cut and hard materials like titanium alloy. However, selection of process parameters for achieving superior surface finish, higher machining rate and accuracy is a challenging task in drilling micro-holes. In this paper, an attempt is made to optimize micro-EDM process parameters for drilling micro holes on titanium grade 19 alloy. In order to verify the optimal micro-EDM process parameters settings, material removal rate (MRR), electrode wear rate (EWR) and over cut (OC) were chosen as the responses to be observed. Pulse on time, pulse off time, electrode diameter and current were selected as the governing process parameters for evaluation by Taguchi method. Nine micro holes of 300 μm, 400 μm and 500 μm were drilled using L9 orthogonal array (OA) design. Optimal combination of machining parameters were obtained through Signal-to-Noise (S/N) ratio analysis. It is seen that machining performances like material removal rate and overcut are affected by the peak current whereas electrode wear is affected by peak current and electrode diameter. Morphology of the micro holes has been studied through SEM micrographs of machined micro-hole.


2014 ◽  
Vol 941-944 ◽  
pp. 1973-1976
Author(s):  
B. Geetha ◽  
K. Ganesan

An investigation was carried out to find out the influence of process parameters on surface roughness (SR) and material removal rate (MRR) in electric discharge machine of Al-7%Si-4%Mg with 20% of red mud Metal Matrix Composites since electric discharge machining is a thermo-electric machining process, an electronic die sinking electric discharge machine was used to drill holes in the composite work piece, copper is used as tool material. Experiment was carried out to find surface roughness, material removal rate and tool wear rate by varying the peak current, flushing pressure of dielectric fluid and pulse on time. It was found that the surface roughness of composite metal increases with the increase peak current ,pulse on time and flushing pressure due larger and deeper craters on the drilled surface. It was also found that there was increase in metal removal rate with the increase in peak current and flushing pressure and slightly decreases with the increase in pulse on time due carbon deposits on the electrodes. Experimental analysis is carried using Taguchi’s Design of Experiment method with various parameters like peak current, flushing pressure of dielectric fluid and pulse on time to identify the key factors that influence the surface roughness, material removal rate and tool wear rate. It was found that the peak current was the most significant parameter that influences surface roughness, material removal rate and tool wear rate. The Taguchi experiments results confirm the actual results obtained from the numerical calculation.


Author(s):  
Munmun Bhaumik ◽  
Kali Pada Maity

Electro discharge machining (EDM) is most popular non-conventional electro-thermal machining process where electrical energy is used to generate a spark and thermal energy used to remove material from the workpiece. The primary goal of EDM is getting more material removal rate (MRR) with lower tool wear rate (TWR). For this investigation, machining parameters like peak current, pulse on time, gap voltage and duty cycle are considered as process parameter, and material removal rate (MRR) and tool wear rate (TWR) are considered as response. AISI 304 stainless steel and tungsten carbide are used as work material and tool material respectively. Taguchi L27 orthogonal array has been applied for designing the experiment. A hybrid optimization technique like desirability in combination with grey relational analysis (GRA) has been performed to get the optimum level of the control parameter for getting higher MRR and lower TWR. Analysis of variance (ANOVA) is performed for the statistical analysis. These results show that peak current is the most significant parameter for MRR and TWR. The optimal parameter setting for maximum MRR and minimum TWR has obtained by desirability coupled with Grey relational analysis.


Sign in / Sign up

Export Citation Format

Share Document