17-08-2012, 02:53 PM
OPTIMIZATION OF MICRO-WIRE EDM OPERATION USING GREY TAGUCHI METHOD
1OPTIMIZATION OF MICRO-WIRE.pdf (Size: 1.63 MB / Downloads: 137)
Abstract
Micro-wire EDM is an emerging technology in the field of Micro-machining to fabricate very
complex micro products. Micro wire EDM is a very complex process involving the different
process parameters. In the present investigation an optimization of micro wire EDM has been
carried out using Grey Taguchi method. The parameters involved are voltage, capacitance, feed
rate and wire speed. MRR and kerf width are taken as the response criteria. Experimental
investigation has been carried out in multi-process Micro-EDM machine.
Wire electrical discharge machining process is a highly complex, time varying & stochastic
process. This is used in the fields of dies, molds; precision manufacturing and contour cutting
etc. any complex shape can be generated with high grade of accuracy and surface finish using
CNC WEDM. The output of the process is affected by large no of input variables. Hence a
suitable selection of input variables for the wire electrical discharge machining (WEDM) process
depends heavily on the operator’s technology & experience. WEDM is extensively used in
machining of conductive materials when precision is of prime importance. Rough cutting
operation in wire EDM is very challenging one because improvement of more than one
performance measures viz. Metal removal rate (MRR), surface finish & cutting width (kerf) are
of prime importance. This paper proposes optimal parameter setting. Using taguchi's parameter
design, significant machining parameters affecting the performance measures are identified as
pulse peak current, pulse on time, and duty factor.
Introduction
Electrical discharge machining (EDM) is one of the must extensively used nonconventional,
thermo-electric metal removal process which encodes material from the work
place by a series of discrete spark between a work and a tool electrode immersed in a liquid
dielectric medium. Electrical energy is used directly to cut the material in final shape. Melting
and vaporization takes place by theses electrical discharges. The minute a mounts of the work
material is then ejected and flushed away by the dielectric medium. The sparks occur at high
frequency which continuously and effectively removes the work prices material by melting and
evaporation. To initiate the machine process electrode and work piece are separated by a small
gap known as ‘spark gap’ which results into a pulsed discharge causing the removal of material.
The dielectric acts as a deionizing medium between two electrodes and its flow helps in vacating
the resoliclified debris to assure optimal conditions for spark generation. In micro-wire EDM
operation the work piece metal is cut with a special metal wire electrode that is programmed to
travel along a definite path. Spark discharges and generated between a small wire electrode and a
work piece to produce complex two dimensional and three-dimensional shapes according to a
NC path.
Conclusions:
It is inferred from the experiment that the table feed and pulse-on time have asignificant
influence on the metal removal rate, the gapvoltage and the total discharge frequency, whereas
the pulse on time has a significant influence on the gap width and the surface roughness
Therefore, adjusting the table feed and T is an appropriate strategy to control the discharging
frequency to prevent the breakage of wire. A larger table feed & a smaller ton are recommended
as longer ton will result in higher value of Ra..