Development, Modeling, and Experimental Investigation of Low Frequency Workpiece Vibration-Assisted Micro-EDM of Tungsten Carbide

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
M. P. Jahan ◽  
T. Saleh ◽  
M. Rahman ◽  
Y. S. Wong
Keyword(s):  
Tungsten Carbide ◽  
Fluid Pressure ◽  
Low Frequency ◽  
Dielectric Fluid ◽  
Micro Edm ◽  
Contributing Factors ◽  
Machining Performance ◽  
Machining Time ◽  
Workpiece Vibration ◽  
Improved Performance

This present study intends to investigate the feasibility of drilling deep microholes in difficult-to-cut tungsten carbide by means of low frequency workpiece vibration-assisted micro–electro-discharge machining (micro-EDM). A vibration device has been designed and developed in which the workpiece is subjected to vibration of up to a frequency of 1 kHz and an amplitude of 2.5 μm. An analytical approach is presented to explain the mechanism of workpiece vibration-assisted micro-EDM and how workpiece vibration improves the performance of micro-EDM drilling. The reasons for improving the overall flushing conditions are explained in terms of the behavior of debris in a vibrating workpiece, change in gap distance, and dielectric fluid pressure in the gap during vibration-assisted micro-EDM. In addition, the effects of vibration frequency, amplitude, and electrical parameters on the machining performance, as well as surface quality and accuracy of the microholes have been investigated. It has been found that the overall machining performance improves considerably with significant reduction of machining time, increase in MRR, and decrease in EWR. The improved flushing conditions, increased discharge ratio, and reduced percentage of ineffective pulses are found to be the contributing factors for improved performance of the vibration-assisted micro-EDM of tungsten carbide.

Study of Micro-EDM of Tungsten Carbide with Workpiece Vibration

2011 ◽  
Vol 264-265 ◽  
pp. 1056-1061 ◽  
Author(s):  
Muhammad Pervej Jahan ◽  
T. Saleh ◽  
Mustafizur Rahman ◽  
Yoke San Wong
Keyword(s):  
Tungsten Carbide ◽  
Surface Quality ◽  
Removal Rate ◽  
Low Frequency ◽  
Electrode Wear ◽  
Micro Edm ◽  
Machining Performance ◽  
Machining Time ◽  
Workpiece Vibration ◽  
Micro Holes

Present study introduces low-frequency workpiece vibration during micro-EDM drilling of difficult-to-cut tungsten carbide with an objective to overcome the difficulty in flushing of debris and machining instability in deep-hole machining. The effects of vibration frequency, amplitude and electrical parameters on the machining performance, as well as surface quality and accuracy of the micro-holes have been investigated. It is found that the overall machining performance improves significantly with significant reduction of machining time, increase in material removal rate (MRR), and decrease in electrode wear ratio (EWR). The surface quality improves and the overcut and taper angle of the micro-holes reduces after applying the workpiece vibration in micro-EDM. The frequency and amplitude of 750 Hz and 1.5 μm were found to provide optimum performance.

The Application of Powder Suspended Dielectric Fluid in Micro-EDM Processes to Reduce Machining Time

2009 ◽  
Vol 1 (3) ◽  
pp. 210-213 ◽  
Author(s):  
Gunawan Prihandana ◽  
Muslim Mahardika ◽  
M. Hamdi ◽  
Kimiyuki Mitsui
Keyword(s):  
Dielectric Fluid ◽  
Micro Edm ◽  
Machining Time

scholarly journals EDM PROCESS PARAMETER OPTIMIZATION FOR EFFICIENT MACHINING OF INCONEL-718

2020 ◽  
Vol 18 (3) ◽  
pp. 473
Author(s):  
Ankit Singh ◽  
Ranjan Kumar Ghadai ◽  
Kanak Kalita ◽  
Prasenjit Chatterjee ◽  
Dragan Pamučar
Keyword(s):  
Wear Rate ◽  
Inconel 718 ◽  
Removal Rate ◽  
Subjective Evaluation ◽  
Fluid Pressure ◽  
Objective Evaluation ◽  
Dielectric Fluid ◽  
Electrode Wear ◽  
Machining Performance ◽  
Edm Process

In the present work, multi-response optimization of electro-discharge machining (EDM) process is carried out based on an experimental analysis of machining superalloy Inconel-718. The study aims at optimizing and determining an optimal set of process variables, namely discharge current (), pulse-on duration () and dielectric fluid-pressure () for achieving optimal machining performance in EDM. Nine independent experiments based on L9 orthogonal array are carried out by using tungsten as the electrode. The productivity performance of the EDM process is measured in terms of material removal rate (MRR) and its cost parameter is measured in terms of tool wear rate (TWR) and electrode wear rate (EWR). The TOPSIS is used in conjunction with five different criterion weight allocation strategies— (namely, mean weight (MW), standard deviation (SDV), entropy, analytic hierarchy process (AHP) and Fuzzy). While MW, SDV and entropy are based on the objective evaluation of the decision-maker (DM), the AHP can model the DM’s subjective evaluation. On the other hand, the uncertainty in the DM’s evaluation is analyzed by using the fuzzy weighing approach.

Study of workpiece vibration in powder-suspended dielectric fluid in micro-EDM processes

2013 ◽  
Vol 14 (10) ◽  
pp. 1817-1822 ◽  
Author(s):  
Gunawan Setia Prihandana ◽  
Muslim Mahardika ◽  
Mohd Hamdi ◽  
Yoke San Wong ◽  
Norihisa Miki ◽  
...  
Keyword(s):  
Dielectric Fluid ◽  
Micro Edm ◽  
Workpiece Vibration

Investigate on Micro-EDM in Air (Dry MEDM) by External Blowing Mode Based on RC Pulse Generator

2011 ◽  
Vol 317-319 ◽  
pp. 334-340
Author(s):  
Li Qing Li ◽  
Guo Zheng Zhu
Keyword(s):  
Pulse Generator ◽  
Feed Speed ◽  
Machining Parameters ◽  
Micro Edm ◽  
Machining Performance ◽  
Range Analysis ◽  
Experimental Conditions ◽  
Copper Electrodes ◽  
Workpiece Vibration ◽  
On Line

Experiments of micro-EDM in gas (dry MEDM) were conducted on the conditions of an external supplying gas mode based on a RC pulse generator. The objective of the work is to optimize machining parameters of the dry MEDM and investigate the machining performance of the ultrasonic induced workpiece vibration. Micro solid copper electrodes were fabricated on line by the block grinding method. Range analysis results of the Taguchi approach indicate that capacitance, servo feed speed have great effect on the material remove rate (MRR); and capacitance and open voltage are main influencing factors on the tool relative wear ratio (TWR). An optimal parameters combination was obtained under the experimental conditions. The experimental results of the ultrasonic induced workpiece vibration demonstrate that high frequency workpiece vibration with a suitable input current could improve MRR and TWR of the dry MEDM.

scholarly journals Numerical Modelling and Optimization of Two-Dimensional Phononic Band Gaps in Elastic Metamaterials with Square Inclusions

2021 ◽  
Vol 11 (7) ◽  
pp. 3124
Author(s):  
Alya Alhammadi ◽  
Jin-You Lu ◽  
Mahra Almheiri ◽  
Fatima Alzaabi ◽  
Zineb Matouk ◽  
...  
Keyword(s):  
Elastic Wave ◽  
Tungsten Carbide ◽  
Composite Structure ◽  
Elastic Waves ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Filling Fraction ◽  
Carbide Composite ◽  
Elastic Metamaterials ◽  
Tungsten Carbide Composite

A numerical simulation study on elastic wave propagation of a phononic composite structure consisting of epoxy and tungsten carbide is presented for low-frequency elastic wave attenuation applications. The calculated dispersion curves of the epoxy/tungsten carbide composite show that the propagation of elastic waves is prohibited inside the periodic structure over a frequency range. To achieve a wide bandgap, the elastic composite structure can be optimized by changing its dimensions and arrangement, including size, number, and rotation angle of square inclusions. The simulation results show that increasing the number of inclusions and the filling fraction of the unit cell significantly broaden the phononic bandgap compared to other geometric tunings. Additionally, a nonmonotonic relationship between the bandwidth and filling fraction of the composite was found, and this relationship results from spacing among inclusions and inclusion sizes causing different effects on Bragg scatterings and localized resonances of elastic waves. Moreover, the calculated transmission spectra of the epoxy/tungsten carbide composite structure verify its low-frequency bandgap behavior.

scholarly journals Hearing at threshold intensities: by slow mechanical traveling waves or by fast cochlear fluid pressure waves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haim Sohmer
Keyword(s):  
Soft Tissue ◽  
Hair Cells ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Fluid Pressure ◽  
Low Frequency ◽  
Frequency Discrimination ◽  
Outer Hair Cells ◽  
Common Mechanism ◽  
Frequency Stimulation

The three modes of auditory stimulation (air, bone and soft tissue conduction) at threshold intensities are thought to share a common excitation mechanism: the stimuli induce passive displacements of the basilar membrane propagating from the base to the apex (slow mechanical traveling wave), which activate the outer hair cells, producing active displacements, which sum with the passive displacements. However, theoretical analyses and modeling of cochlear mechanics provide indications that the slow mechanical basilar membrane traveling wave may not be able to excite the cochlea at threshold intensities with the frequency discrimination observed. These analyses are complemented by several independent lines of research results supporting the notion that cochlear excitation at threshold may not involve a passive traveling wave, and the fast cochlear fluid pressures may directly activate the outer hair cells: opening of the sealed inner ear in patients undergoing cochlear implantation is not accompanied by threshold elevations to low frequency stimulation which would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. The magnitude of the passive displacements at threshold is negligible. Isolated outer hair cells in fluid display tuned mechanical motility to fluid pressures which likely act on stretch sensitive ion channels in the walls of the cells. Vibrations delivered to soft tissue body sites elicit hearing. Thus, based on theoretical and experimental evidence, the common mechanism eliciting hearing during threshold stimulation by air, bone and soft tissue conduction may involve the fast-cochlear fluid pressures which directly activate the outer hair cells.

Drehen von ausferritischem Gusseisen*/Turning of austempered ductile iron – Impact of inhomogeneous cutting edge geometry on wear mechanism and machining result

2018 ◽  
Vol 108 (10) ◽  
pp. 736-742
Author(s):  
J. Hartig ◽  
B. Kirsch ◽  
J. Aurich
Keyword(s):  
Tungsten Carbide ◽  
Tool Life ◽  
Wear Mechanism ◽  
Ductile Iron ◽  
Cutting Edge ◽  
Machining Process ◽  
Austempered Ductile Iron ◽  
Machining Performance ◽  
Edge Geometry ◽  
Homogeneous Preparation

Mit Schneidkantenpräparation kann das Werkzeug im Zerspanprozess an die Bearbeitungsaufgabe angepasst werden. Homogene Präparationen können dabei entweder auf hohe Belastungen des Werkzeugs oder ein optimiertes Bearbeitungsergebnis im Sinne der Oberfläche ausgelegt werden. In diesem Beitrag wurden die Schneidkanten von Hartmetall-Wendeschneidplatten unterschiedlich inhomogen präpariert, um den unterschiedlichen Anforderungen entlang des Eingriffs Rechnung zu tragen. Neben der Werkzeugstandzeit wurde das Prozessergebnis beim Außenlängs-Runddrehen von ausferritischem Gusseisen (ADI) 900 untersucht.   The preparation of cutting edges allows for tools to be tailored to the machining process. A homogeneous preparation can either be designed for high loads in the machining process or an optimized machining result on the surface. In this article, the cutting edges of tungsten carbide indexable inserts were prepared inhomogeneously and thus individually matched to the machining task. Tool life and machining performance while turning austempered ductile iron (ADI) 900 were investigated.

Low Frequency of Adenylate Kinase Release into Cerebrospinal Fluid during Balanced, Normotensive Anaesthesia and a Non-Orthognathic Surgical Procedure

1997 ◽  
Vol 25 (2) ◽  
pp. 92-97 ◽  
Author(s):  
M Enlund ◽  
O Mentell ◽  
L Edmark ◽  
G Ronquist
Keyword(s):  
Cerebrospinal Fluid ◽  
Adenylate Kinase ◽  
Orthognathic Surgery ◽  
Cell Injury ◽  
Low Frequency ◽  
Brain Cell ◽  
Contributing Factors ◽  
Oscillating Saw ◽  
The Difference ◽  
Increased Activity

Activity of strictly intracellular enzymes in the cerebrospinal fluid (CSF) may indicate leakage from dysfunctional brain cells. Increased activity of adenylate kinase (AK) in the CSF is indicative of brain cell injury arising from several sources, among them orthognathic surgery. The mechanism in the latter case is obscure, but the use of an oscillating saw which generates vibrations, and the site of surgery close to the brain may be contributing factors. Anaesthesia may also play a role. In the present study, CSF-AK activity was measured after hysterectomy and was compared with activity after orthognathic surgery in two other studies. Four of 19 patients (21%) in the present study expressed pathological activity, compared with 34 of 47 (72%) orthognathic patients in the two other studies. No firm conclusion may be drawn from historical comparisons, and the difference in activity seen between the two types of surgery might not necessarily be the result of surgical factors. Until this is investigated further, however, we conclude that there may be a difference in postoperative CSF-AK activity between orthognathic and lower abdominal surgery.

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