Fixed Machining Parameter
Main Power Supply Voltage
Electrode Material
Machining Polarity
Dielectric Fluid
Setting (Machine Unit)
40
Copper
(-)
Distilled water
Table 1: Settings of Fixed Machining Parameters
Variable Machining Parameter
Workpiece Material
Workpiece Thickness (mm)
Diameter of Electrode, De (mm)
Nominal capacitance, C (µF)
Level 1
Brass
0.03
0.3
100
Level
Level 2
Stainless Steel
0.08
0.5
220
Level 3
0.15
0.8
330
Table 2: Conditions of Variable Machining Parameters
Responding factor
Material Removal Rate
(MRR)
Electrode Wear Ratio
(EWR)
Circularity of Hole
Description
- This is the measure of cutting rate of the workpiece.
- It is measured by weighing the workpiece before and after machining
over machining time.
- If MRR is high, the productivity is high.
- This is the measure of an electrode life span.
- It is measured by weighing the electrode before and after machining
over machining time.
- If the ratio high, then the electrode is eroding faster.
- This is the measure of hole quality fabricated.
- It is measured by a light optical microscope on the diameter of the
holes
- If the circularity is good, the image observed under microscope
shows a perfect circle.
Table 3: Descriptions of Machining Performances
including MRR, EWR and circularity of formed micro
holes is shown in Table 3.
One of the most frequently used methods in
determining the effect of machining parameters
on the machining performances by micro-EDM
is the Taguchi method. The Taguchi method is
a statistical technique for deciding the optimal
setting of a DOE experiment, thus improving the
performance and manufacturability of products as
well as reducing process variability. Some simple
calculations are used to find out the required
result. The results needed are MRR, EWR and
circularity of fabricated micro hole (Jahan et al.,
2008). In this study, the circularity of the micro
holes was measured by using a Dino-Lite Pro
Digital Microscope. Several readings were taken
for each experiment to increase the accuracy
of the data collected. There are some simple
calculation methods for MRR and EWR:
MRR= Initial mass of workpiece-Final mass of workpiece
(1)
Machining time
EWR= Initial mass of electrode-Final mass of electrode (2)
Initial mass of workpiece-Final mass of workpiece
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