INGENIEUR
Figure 3 PEDM in action, electrode and
workpiece submerged in dielectric fluid
a predetermined distance between
the tool electrode and work-piece is
reached;
● ●
a second step to determine whether if
the RC discharge terminal has sufficient
potential difference;
● ●
a third step of retracting the tool electrode
in the event the RC discharge terminal is
shown to not have sufficient potential
difference when the predetermined
distance is reached; and
● ●
a fourth step of halting the approach of
the tool electrode when a predetermined
depth of cut is achieved and, if necessary
repeating steps 1 to 3 until a predetermined
depth of cut is reached.
The EDM power supply is a RC discharge
system. The electrical setup of an EDM controller
comprised three different units, namely: EDM
power controller, EDM motion controller and XY
position controller. The schematic diagram for the
EDM controller connection is shown in Figure 2.
Performance Evaluation of PEDM
Figure 4 PEDM in action before sparking
Figure 5 PEDM in action during sparking
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Figures 3 to 5 show the Micro-EDM in action,
submerged in dielectric fluid, before sparking and
during sparking. Design of Experiment (DOE) is a
technique used to analyse the specific responding
variables by experimentally changing certain
manipulated variables. It is an efficient statistical
method that can be used to get experimental
results. DOE performance evaluations are divided
into three categories - machining parameter
selection, machining performance selection and
method selection. The electrode material used
in this study was copper. Copper provides high
dimensional precision, high surface quality and high
cutting speed (Khan et al., 2009). Copper electrode
diameters of 0.3mm, 0.5mm and 0.8mm were
used. Table 1 shows the settings of fixed machining
parameters, while Table 2 shows variable machining
parameters. The fixed machining parameters include
power supply voltage, electrode material, machining
polarity, peak current and dielectric fluid. The variable
machining parameters include nominal capacitance,
feed rate, electrode diameter, thickness and work-
piece material chosen to investigate the effect on
machining performances. Machining performance,