1. International INTERNATIONAL Journal of Mechanical JOURNAL
Engineering OF and MECHANICAL Technology (IJMET), ISSN ENGINEERING
0976 6340(Print), ISSN 0976 6359(Online), Volume 5, Issue 7, July
(2014), pp. 80-100 IAEME AND TECHNOLOGY (IJMET) ISSN 0976 6340
(Print) ISSN 0976 6359 (Online) Volume 5, Issue 7, July (2014), pp.
80-100 IAEME: www.iaeme.com/IJMET.asp Journal Impact Factor (2014):
7.5377 (Calculated by GISI) www.jifactor.com 80 IJMET I A E M E
EFFECT OF VIBRATION ON MICRO-ELECTRO-DISCHARGE MACHINING Amol S.
Todkar1, Dr. M.S. Sohani2, Prashant R. Patil3, P. N. Deshmukh4 1,
3, 4(Department of Mechanical Engineering, TKIET, Warananagar,
Kolhapur, India) 2(Professor, Department of Mechanical Engineering,
AITM, Belgaum, India) ABSTRACT The Principal objective of the
research work is decided to carryout Response Surface Methodology
(RSM) based investigations into the effect of Voltage, Capacitance
and work piece vibration Frequency, amplitude on different
materials. The RSM based mathematical models of Material Removal
Rate (MRR) and Tool Wear Rate (TWR) have been developed using the
data obtained through Central Composite Design (CCD). The Analysis
of Variance (ANOVA) was performed along with Fishers statistical
test (F-test) to verify the lack-of-fit and adequacy of the
developed mathematical models for the desired confidence interval.
The ANOVA table includes sum of squares (SS), degrees of freedom
(DF) and mean square (MS). In ANOVA, the contributions for SS is
from the first order terms (linear), the second order terms
(square), the interaction terms, lack of fit and the residual
error. The lack of fit component is the deviation of the response
from fitted surface, whereas the residual error is obtained from
the replicated points at the center. The MS are obtained by
dividing the SS of each of the sources of variation by the
respective DF. The p-value is the smallest level of significance at
which the data are significant. The Fishers variation ratio
(F-ratio) is the ratio of the MS of the lack of fit to the MS of
the pure experimental error. As per the ANOVA technique, the model
developed is adequate within the confidence interval if calculated
value of F-ratio of lack of fit to pure error does not exceed the
standard tabulated value of F-ratio and the F-values of model
should be more than the F-critical for a confidence interval.
Further, conformation test was performed to ascertain the accuracy
of the developed models. The entire research work is experiment
oriented and the conclusions are drawn based on graphical analysis
of experimental results. The research work carried out reveals that
the findings are encouraging in establishing the effect of Voltage,
Capacitance and work piece vibration Frequency, amplitude on
different materials EDM drilling process performance
characteristics. The results of this investigations can be adopted
in deciding the optimal values of input process parameters EDM
drilling process.
2. International Journal of Mechanical Engineering and
Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online),
Volume 5, Issue 7, July (2014), pp. 80-100 IAEME Keywords:
Electrical Discharge Machining (EDM), Central Composite Design
(CCD), Material Removal Rate (MRR), Tool Wear Rate (TWR), Response
Surface Methodology (RSM). Analysis of Variance (ANOVA). 81
Abbreviations I Discharge current ton Pulse on time toff Pulse of
time A Tool area MRR Material removal rate TWR Tool wear rate WRW
Workpiece removal weight TWW Tool wear weight Density T Machining
time R.No Run number F Fisher ratio R2 Coefficient of determination
INTRODUCTION The basis of controlling the micro electro-discharge
machining (EDM) process mostly relies on empirical methods largely
due to the stochastic nature of the sparking phenomenon involving
both electrical and nonelectrical processes parameters. Thus the
performance of micro electro-discharge machining (EDM) process is
commonly evaluated in the terms of Material Removal Rate (MRR) and
Tool Wear Rate (TWR); and to compute MRR and TWR mathematical
models are developed. Modeling and analysis of Material Removal
Rate (MRR) and Tool Wear Rate(TWR) with the effect of processes
parameters like Voltage, Capacitance & Amplitude, Frequency of
Vibration on different workpiece thickness is described in this
investigation. Conventional Statistical Regression analyses based
mathematical models have been developed to establish the input out
put relationships. Material Removal Rate (MRR) and Tool Wear
Rate(TWR) mathematical models have been developed using the data
obtained through Central Composite Design(CCD) The lack-of-fit and
adequacy of the developed mode was verified by applying Analysis of
Variance (ANOVA).Further the conformation tests were performed to
ascertain the accuracy of the developed models.[1] EXPERIMENTAL
DETAILS Experimental set-up In the present investigation, the
experiments were performed in Electronica machine tool EDM Drill
(Rapid drill -II) machine. Fig. 2 shows a photograph of EDM
machine. The specifications of micro EDM machine are shown in the
Table 1.1 The electrolytic copper is used as a tool material
because of its higher MRR and less TWR, it also yields a better
surface finish. The electrolytic copper tools with different size
used to erode water quenched steel k 340 workpiece. The impulse
flushing of tap water (dielectric fluid) was employed throughout
the experimental investigations. The other quantitative and
qualitative micro EDM processes parameters were kept constant for
given set of trials.
3. International Journal of Mechanical Engineering and
Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online),
Volume 5, Issue 7, July (2014), pp. 80-100 IAEME 82 Fig. 1:
Schematic diagram of the developed vibration unit Vibration Unit A
simple vibration device has been designed and developed. In order
to create a low frequency oscillation on the work piece (Fig.4). An
electromagnet is used as the actuator. The electric power is
supplied periodically to the electromagnet with the help of a power
transistor switch. The on-off sequence of the power transistor is
controlled by a frequency controllable pulse generator. When the
switch is kept on, the electricity flowing through the circuit
causes the electromagnet to be energized, which triggers a pull
action on the vibration pad. The flexure beams are bent at that
time. Again, the electromagnet is de-energized when the transistor
switch is turned off, causing the flexure beams to release and push
the vibration pad in upward direction. In this way, a low frequency
vibration is induced on the work piece during micro-EDM. Fig.2:
Photograph of electronica machine tool EDM drill (rapid drill
-ii)
4. International Journal of Mechanical Engineering and
Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online),
Volume 5, Issue 7, July (2014), pp. 80-100 IAEME 83 Table 1.1:
Electronica machine tool edm drill (rapid drill) Technical
Specifications Machine Tool Rapid drill II Work table 450 x 300 mm
(Granite) X & Y axes travel 350, 250 mm Z axis travel 350 + 300
mm Max. Electrode length 400 mm Size of electrode dia. 0.3-3.0 mm
Max. drill depth 300 mm Max. coolant pressure 6 MPA Max. weight of
the workpiece 350 kg Connected load 3 kVA Work tank 800 x 450 mm
Input power supply 3 phase, AC 415 V*, 50Hz Net Weight 750 kg
Machine foot print 950 x 850 x 1980 mm Max. machining current 30 A
TECHNOLOGY Job material Steel/Brass/Aluminium/Carbide/other
conducting materials Dielectric Tap water/ Coolant soap Max.
drilling speed 20-60mm/min (dia0.5 mm) Materials used for the
experiments Work piece material 1) Work piece material used for the
experiment was K340 steel with the density of 7.77g/cm and After
quenching of 1040 C and 520 ~ 530 C high temperature tempering, the
hardness of HRC up to 62 to 63. Table 4.2 depicts the chemical
composition of K340 steel. Table 1.2: Chemical Composition Of K340
Steel By Weight Percentage C Si Mn Mo V Cr P 1.00 0.91 0.32 2.00
0.28 8.00 0.007 2) Iron sinter is the thermally agglomerated
substance formed by heating a variable mixture of iron ores, finely
divided coke, limestone, blast furnace dust, steelmaking dust, mill
scale and other miscellaneous iron bearing materials in the
temperature range 1315 to 1480C. The product iron sinter is used
exclusively as a burden material in the production of iron in the
blast furnace. The
5. International Journal of Mechanical Engineering and
Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online),
Volume 5, Issue 7, July (2014), pp. 80-100 IAEME identity of iron
sinter is summarized in Table 1.The typical [sameness]
specification for Iron Sinter is given in Table 2. 84 Table 1.3:
Identity Of Iron Sinter Chemical name Iron, sinter IUPAC name Other
names (usual name, trade name, Iron sinter abbreviation) EINECS No.
265-9979 CAS name and CAS No. 65996-669 Other identity code:
Related CAS No. Hematite (Fe2O3) 1317-608 Molecular formula Fe2O3
Structural information (Crystal lattice) Minerals of identical or
similar composition Hematite MW (g/mole) MW (g/mole) 159.69 Table
1.4: Sameness Specification For Iron Sinter Constituent Typical
range, % m/m Fe2O3 >55 FeO