Experimental Analysis of Reverse Micro-EDM for Machining Microtool

Chandrasekaran

2020

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Drilling of micro-hole with fine edges and smooth internal surfaces finds numerous applications in manufacturing industries; holes drilled in injection nozzles, drug delivery orifices and spinneret holes are some of examples. This work carries out an experimental investigation and parametric optimization on micro-hole drilling using micro-electrical discharge machining (µ-EDM) process. The machining experiments are conducted employing Taguchi L16 orthogonal array for evaluating machining time (t) average overcut (AOV), taper angle (TA), entry overcut (EnOV), exit overcut (ExOV) and material removal rate (MRR) as process performances, while voltage (V), capacitance (pF) and feed rate (µm/s) are considered as process parameters. The influence of process parameters on the responses is studied at different cutting conditions. The drilled microholes profile is studied in terms of burrs, craters, spots on the edges and internal surfaces using micrographs obtained with optical and scanning electron microscopes. The ANOVA result reveals that capacitance is the most significant parameter for t, AOV, TA, MRR, EnOV and ExOV. For simultaneous optimization of three performance measures (i.e., t, AOV and TA), an overall evaluation criterion has been evaluated and optimum cutting conditions such as voltage: 80 V, capacitance: 100 pF and feed rate: 15 µm/s are obtained. The expected outcome obtained at the optimum condition is improved by 10.57% (36.934 to 40.839) over the grand average of performance. The confirmation experimental result at optimum cutting condition (i.e., 39.378) is comparable with the expected result (i.e., 40.839).

Section: Introductionmentioning

confidence: 99%

Experimental study on drilling micro-hole through micro-EDM and optimization of multiple performance characteristics

Singh

Chandrasekaran

2020

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“…The performance measures have been evaluated based on the microscopic data and by using Eqs. (4)(5)(6). The machined area is assumed to be the half of the volume of spring as the thread is semicircular.…”

Section: Resultsmentioning

confidence: 99%

“…Traditionally, die sinking EDM is used to machine holes or to form cavities on workpiece [4]. Nowadays, die sinking micro-EDM is used for precise machining in microscale [5]. In both cases, a shaped tool is used as an electrode.…”

Section: Introductionmentioning

confidence: 99%

Concept development for fabricating threaded micro-pin using wire-EDM

Debnath

2019

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Nowadays miniaturization with precision is an important requirement in the field of medical devices and high-end applications. This work introduces the concept of 3D complex geometry fabrication in microscale using typical 2-Axis wire-cut electric discharge machine (WEDM). In this regard, the threaded profile micro-pin has been chosen in the present study. Synchronizing the workpiece rotating speed with feed rate along with a suitable depth of cut is the required condition for fabricating a screw. A separate attachment has been developed and used to rotate the workpiece at different speeds. Further, a CNC code has been generated to design the tool path with the required tool feed and depth of cut. Initially, turning operation has been performed which results in reduction in the tool diameter into the desired dimension along with the elimination of the eccentricity of the rotating rod. Consequently, the thread cutting operation has been accomplished with the adjusted set of parameters. Besides, the surface topography and material characteristics of the fabricated screw fin have also been observed based on scanning electron microscopic images and energy-dispersive X-ray analysis. Finally, the established process has been escalated further to fabricate screws of minimum possible dimension using the WEDM.

“…However, in this process, erosion rate is not as fast as conventional EDM due to the small pulse energy involved during the machining process. From the last decade, one of the variants of µEDM which is known as reverse µEDM (R-µEDM) has been gaining popularity for the fabrication of single-as well as multiple-tipped micro-rod of various shapes with high aspect ratio [10][11][12][13][14][15][16]. Multiple-tipped micro-rods have a plenty of applications in industries such as drilling of micro-holes in probe card for testing semiconductor device and perforated shadow mask with various shapes which are used in CRT monitors.…”

Section: Introductionmentioning

confidence: 99%

“…The reciprocating motion of the debris particles and the flow reversal of the dielectric fluid improve the overall process stability, which was totally absent in case of inter-electrode gap which is in a fixed condition (in case of without vibration-assisted). Singh et al [16] have contributed some work on R-µEDM, in which they discussed the machining of straight and target length of micro-rod. They machined a straight micro-rod with a target length of 1 mm.…”

Section: Introductionmentioning

confidence: 99%

Analysis of micro-rods machined using reverse micro-EDM

Singh

Deshpande

2018

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In today's world, microstructures have a wide range of applications in the field of biomedical devices, aerospace engineering, MEMS device elements, etc. In the recent years, reverse micro-electro-discharge machining (R-µEDM) has evolved from µEDM that has become one of the promising technologies to fabricate precise components and microstructures of various shapes with high aspect ratio. In this work, micro-tools (rods) of average size (diameter) 182 µm have been machined using copper sheet from bulk tungsten rod of 800 µm diameter by R-µEDM process. Moreover, Taguchi's L16 orthogonal array has also been applied for designing the experiments. Feed rate, capacitance and voltage are considered as the parameters of the process. The response parameters such as machining time, erosion rate and dimensional variation have been analyzed in detail for different combinations of the process parameters. It is a well-known fact that the tool wear is the main culprit and responsible for the error in the micro-rods. Dimensional error has been quantified over the entire length of the micro-rods through the measurement process, and the minimum standard deviation is found to be 1.13 µm at a feed rate of 5 µm/s, capacitance of 1000 pF and voltage of 120 V. Further, machining data have been collected in real time and the behavior of machining time with work feed has been studied. In addition to it, a simple analytical model has been developed for calculating the erosion rate and it is seen that voltage produces more effect on erosion rate and machining time than the other parameters. Additionally, using the feed rate, capacitance and voltage at which minimum deviation took place, an array of 4 × 4, i.e., 16 micro-rods with 58 µm diameter and 830 µm length, has been fabricated on the bulk tungsten rod of 800 µm diameter.