scholarly journals Effect of Conductive Coatings on Micro-Electro-Discharge Machinability of Aluminum Nitride Ceramic Using On-Machine-Fabricated Microelectrodes

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3316 ◽  
Author(s):  
Asif Rashid ◽  
Azat Bilal ◽  
Chong Liu ◽  
M. P. Jahan ◽  
Didier Talamona ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Aluminum Nitride ◽  
Load Condition ◽  
Machining Process ◽  
Composition Analysis ◽  
Micro Edm ◽  
Micro Holes ◽  
Machining Of Ceramics ◽  
Edm Process ◽  
Machined Surfaces

The objective of this study is to investigate the feasibility of machining micro-holes on the non-conductive Aluminum Nitride (AlN) ceramics using micro-electro-discharge machining (EDM) process by exploiting various coating techniques. Although ceramics possess excellent mechanical properties under compressive load condition and superior thermal properties, machining of microscale features on ceramics remains challenging due to the extreme brittleness associated with ceramics. Due to the involvement of higher cutting force and tool wear issue, conventional machining process appears to be unsuitable for machining ceramics. On the other hand, non-contact and negligible process force associated with EDM process makes it one of the competitive processes for machining of ceramics. A series of experiments were carried out on AlN ceramics using “Assistive Electrode” micro-EDM process with a goal of machining blind micro-holes into the ceramics with the aid of on-machine fabricated copper tungsten tools. It was found that multi-layer coatings of silver and copper with copper tungsten electrode resulted in successful machining with high-aspect-ratio holes during powder mixed micro-EDM of AlN ceramics, while micro-holes with less than one aspect ratio are machined without powder addition to the dielectric. It was also observed that comparatively lower level of discharge energies, i.e., lower value of voltages and capacitances were favorable for successful machining of micro-holes in ceramics, even though it results in significantly higher machining time. Despite of relatively low discharge energy usage in micro-EDM, machined surfaces appear to be very rough. The machined surfaces indicate that melting and evaporation, as well as thermal spalling, are the dominating material removal mechanisms. The machined surfaces contained many thermal cracks and porosity on the surface. The elemental composition analysis confirms the presence of aluminum and nitrogen elements on the machined surface. Finally, by careful selection of machining conditions and assistive electrode, successful machining of micro-holes is possible on the non-conductive ceramic surfaces using the micro-EDM process.

Study to Enhance the Precision of Micro-EDM

2007 ◽  
Vol 339 ◽  
pp. 26-31 ◽  
Author(s):  
Bao Xian Jia ◽  
Wan Sheng Zhao ◽  
Zhen Long Wang ◽  
Fu Qiang Hu
Keyword(s):  
Machining Process ◽  
Micro Edm ◽  
Pulse Power Supply ◽  
Simple Method ◽  
Forming Mechanism ◽  
System A ◽  
Micro Holes ◽  
Energy Pulse ◽  
And Control ◽  
Edm Process

Considering the key technologies to enhance the accuracy of micro-EDM, a micro-EDM system and some techniques are researched. In this system, a micro-energy pulse power supply whose open voltage and capacitance can be adjusted is developed. The detection and control subsystem of the machining process is designed and applied. A simple method of machining high precision microelectrodes is adopted. The forming mechanism of the gap in EDM process is analyzed theoretically. The processing experiments are carried out on the system, and the results basically coincide with the theoretical analysis. The experimental results of machining microelectrodes and micro holes show that the Ø4.5±0.5μm microelectrodes can be ground, and the Ø6±2.0μm micro holes can be drilled.

Experiment Study of Combining Micro EDM with USM

2008 ◽  
Vol 375-376 ◽  
pp. 248-252
Author(s):  
Bao Xian Jia ◽  
Dong Sheng Wang ◽  
Zhen Long Wang ◽  
Wan Sheng Zhao
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Power Supply ◽  
Pulse Power ◽  
Machining Process ◽  
Micro Edm ◽  
Pulse Power Supply ◽  
Experiment Study ◽  
Workpiece Vibration ◽  
Micro Holes

Experiments of combining micro EDM with USM are carried out to enhance the machining ability and flexibility of the micro EDM, improve the machining state, and increase the productivity and aspect ratio of the micro holes. Basing on RC pulse power supply and workpiece vibration, the micro holes are drilled. The results of comparing experiments indicate that in the processes of both micro EDM without USM and micro EDM with USM, the machining velocity and the wear of the electrode increase with the increase of open voltage and loop capacitance. The experiment results of amplitude influencing on the machining process indicate that with the increase of ultrasonic amplitude, the machining velocity heightens and the aspect ratio of the micro holes augments; at the same time, however, the wear of the electrode and the extensive magnitude of the holes increase. Micro holes with some cross-section and accurate profile are drilled steadily.

Generation of High Aspect Ratio Micro Holes by a Hybrid Micromachining Process

2007 ◽  
Author(s):  
Murali M. Sundaram ◽  
Sridevi Billa ◽  
Kamlakar P. Rajurkar
Keyword(s):  
Aspect Ratio ◽  
Ultrasonic Vibration ◽  
Machining Process ◽  
Hole Drilling ◽  
Micro Edm ◽  
Shape Distortion ◽  
Machining Time ◽  
Machined Surface ◽  
Electro Discharge Machining ◽  
Debris Removal

Drilling a micro hole with an aspect ratio above 10 is a challenging task for any-micromachining process. In micro electro discharge machining (micro EDM), a proven metallic micromachining process, this is due to the problems associated with debris removal. In such cases, where the capabilities of existing macro machining methods are constantly being challenged, innovative micro manufacturing approaches are required to make progress. Hybrid micromachining is one such approach in which the synergy of constituent processes is exploited to achieve desired results. In this paper, the results of ultrasonic vibration assisted micro electro discharge machining process are presented. This hybrid process is capable of deep hole drilling with aspect ratio of 20 in austenitic stainless steel by overcoming the limitations in the debris removal faced in the typical micro EDM process. Other benefits of ultrasonic vibration are the savings in machining time, and less tool wear. It is also noticed that the ultrasonic vibration causes some shape distortion and produces rougher machined surface.

Investigating the Effect of Machining Parameters on Microdrilling of Titanium Grade 19 Alloy

2013 ◽  
Author(s):  
Shivraj Yeole ◽  
Nagabhushana Ramesh Nunna ◽  
Balu Naik Banoth
Keyword(s):  
Process Parameters ◽  
Material Removal ◽  
Removal Rate ◽  
Electrode Wear ◽  
Machining Parameters ◽  
Micro Edm ◽  
Electrode Diameter ◽  
Micro Holes ◽  
Titanium Grade ◽  
Edm Process

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.

Modeling Aspect Ratio of a Micro EDM Hole

2010 ◽  
Vol 126-128 ◽  
pp. 829-834
Author(s):  
G. Yin ◽  
Z. Yu ◽  
C. An ◽  
J. Li
Keyword(s):  
Aspect Ratio ◽  
Electrical Discharge Machining ◽  
Micro Edm ◽  
Metallic Materials ◽  
Micro Electrical Discharge Machining ◽  
Proposed Model ◽  
Micro Holes ◽  
Micro Hole ◽  
The Difference ◽  
Discharge Gap

Micro electrical discharge machining (EDM) has the ability to drill micro holes with high accuracy in metallic materials. The aspect ratio of a micro hole generated by micro EDM is usually higher than those by other processes such as etching, mechanical drilling, and laser. However, it was found that the drilling speed of micro EDM slows down and even stops when the aspect ratio reaches a certain value. To understand this phenomenon, a theoretical model is proposed based on the fluid mechanics and surface tension. Experiments under different machining conditions are carried to verify this model. Experimental results agree with the theoretical values, which indicate the validity of the proposed model. The difference between the theoretical values and the real values might be caused by the debris and the temperature in the discharge gap, which are ignored in the model.

Research of PZT Excited Discharge Channel Compression Micro-EDM Techniques

2013 ◽  
Vol 645 ◽  
pp. 363-366
Author(s):  
Lian Ming Du ◽  
Qin He Zhang ◽  
Jian Hua Zhang ◽  
Ya Zhang
Keyword(s):  
Discharge Channel ◽  
Removal Rate ◽  
New Technology ◽  
Machining Process ◽  
Micro Edm ◽  
System Composition ◽  
The Stability ◽  
Discharge Gap ◽  
Edm Process ◽  
Sync Pulse

In micro-EDM, the debris generated in machining process is difficult to be moved from the discharging gap, the discharge state is instability, and the material removal rate is low. A new method of PZT incentive synchronous compression discharge channel micro-EDM is presented based on the inverse piezoelectric effect of PZT piezoelectric ceramics, using a spark discharge and PZT sync pulse power. In this paper, the system composition and machining principles are described in detail, and its machining mechanism is analyzed in terms of the experiments. By the experiments, it is certificated that on the process of PZT sync compressing discharge channel machining, the state of discharge gap, the machining efficiency and quality can be improved, the throw out of debris makes easier, and then the stability of micro-EDM process is raised, which indicated that this new technology has wide application prospect in the field of micro manufacturing.

High Aspect Ratio and Complex Shaped Blind Micro Holes by Micro EDM

CIRP Annals ◽  
2002 ◽  
Vol 51 (1) ◽  
pp. 359-362 ◽  
Author(s):  
Z.Y. Yu ◽  
K.P. Rajurkar ◽  
H. Shen
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Micro Edm ◽  
Micro Holes

Analysis of accuracy of high-aspect-ratio holes generated using micro-electric discharge machining drilling

2008 ◽  
Vol 222 (11) ◽  
pp. 1453-1464 ◽  
Author(s):  
M S Puranik ◽  
S S Joshi
Keyword(s):  
Aspect Ratio ◽  
Electric Discharge ◽  
High Aspect Ratio ◽  
Processing Parameters ◽  
Industrial Applications ◽  
Tool Electrode ◽  
Micro Edm ◽  
Electric Discharge Machining ◽  
Debris Accumulation ◽  
Micro Holes

Micro-electric discharge machining (micro-EDM) has evolved as one of the prominent processes to generate high-aspect-ratio and accurate micro-structures in many industrial applications. This paper presents an extensive experimental analysis of the micro-EDM process to explore the relationship between accuracy as a function of depth of micro-holes drilled using micro-EDM drilling. It is shown that a depth of 5.0 mm can be achieved by a 200 μm diameter tool electrode while controlling the regular process parameters, but beyond this length, the process is governed by a number of derived phenomena such as secondary sparking, debris accumulation, etc. instead of the regular processing parameters. The optimum depth of the hole that could be achieved with a good accuracy i.e. a minimum oversize lies between 2.5 and 5.0 mm, the largest depth that could be achieved was 8.33 mm. The highest aspect ratio achieved in this experiment was 15.63.

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