Assignment of weights method for the optimization of ti n coated carbide reaming

1. INTERNATIONAL JOURNAL OF ADVANCED RESEARCH IN ENGINEERING
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 31-40 © IAEME
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Volume 5, Issue 9, September (2014), pp. 31-40
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ASSIGNMENT OF WEIGHTS METHOD FOR THE OPTIMIZATION OF TiN
31
COATED CARBIDE REAMING
Siby Varghese1, Josephkunju Paul C.2, S. Karunanidhi3
1P. G. Scholar, Department of Mechanical Engineering,
Mar Athanasius College of Engineering, Kothamangalam, Kerala, India
2Professor and Head, Department of Mechanical Engineering,
Mar Athanasius College of Engineering, Kothamangalam, Kerala, India
3Scientist G and Dy. Director, Research Centre Imarat, DRDO, Hyderabad, India
ABSTRACT
All the engineering fields, especially in the aerospace applications and the defense field are
developing and advancing in technology day by day. The manufacturing of Electro Hydraulic Servo
Valve (EHSV) considered for this work is a two stage electrically operated hydraulic valve, in which
the output flow is proportional to the input current. The material used for EHSV is SS 440 C. In the
manufacturing of EHSV, the cylindrical bores are manufactured using the wire electric discharge
machining (WEDM). The problems associated with WEDM including its high surface roughness
value, high cylinricity, increased time for manufacturing cylindrical bores and high costs associated
with its production can only be eliminated by replacing the existing WEDM process with suitable
process which is cost effective, time saving and produce components with better quality. For this
purpose TiN coated carbide reamer is the best option to overcome the above mentioned problems for
the manufacturing of cylindrical bores. This study investigates the effects of various parameters such
as speed, feed and allowance on the surface finish and cylindricity of the EHSV valve body.
‘Assignment of weights’ method is used to find the combinations of the above mentioned parameters
to get the optimum results.
Keywords: Assignment of Weights, MRPI Plot, Taguchi’s Design of Experiments, Tin Coated
Carbide Reamer, WEDM.

2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 31-40 © IAEME
32
1. INTRODUCTION
Wire EDM is most extensively use techniques in manufacturing components with intricate
shapes and profile. But this process is not suitable for manufacturing components with cylindrical
bores and uniformly tapered bores, as they are time consuming and costly process. Application of
advanced reamers like TiN coated carbide reamer can be used to overcome the problems related to
manufacturing of cylindrical and tapered bore manufacturing of components in precision
manufacturing. Technological and economical comparison, surface integrity, corner error, crater,
corrosion, etc. of WEDM process where studied with the help of literatures [1], [2], [3], [4], [6], [7],
[8], [9], [10].
While considering the manufacturing of EHSV, the WEDM is applied for the manufacturing
of cylindrical bores in the EHSV valve body. But it is a time consuming and costly process. Also
WEDM has several disadvantages as seen from several journals. So advanced process such as special
purpose reaming process can be used instead of WEDM process for cylindrical bore manufacturing.
Reaming is common machining process for enlarging, smoothing and accurately sizing existing
holes to tight tolerances [5]. International manual [14] for special purpose tools gives a complete idea
about the type of tools that suitable for different work materials. In that manual the type of reamer
suitable for machining SS 440C is found as TiN coated carbide reamer. It was found that the most
influencing parameter for reaming process are speed, feed, depth of cut and allowance. In this work,
depth of cut is not considered as the variable parameter; as it can only be varied according to the
length of spool bore. Reaming was retained for finishing, as a process capable of yielding required
results when performed on inexpensive machine tools such as drill press with simple fixtures.
Reaming is suitable for batch production typically of job shops, facing the challenges of meeting
specifications at competitive costs.
Better surface finish and bore geometry can be obtained with the help of reaming process.
Apparently minor influences led to enhanced process control and substantially better results at no
extra cost. Results supported selection of production parameters meeting specified quality and cost
targets, as well as substantial improvements [11]. From [13] it was found that average surface
roughness for reaming range between 0.8 μm and 3.2 μm, but high-accuracy reaming can produce
average surface roughness as low as 0.4 μm. The quality of the reamed holes was evaluated in terms
of geometrical characteristics (diameter, roundness, cylindricity and surface roughness). Roundness
as well as cylindricity was verified to be smaller than the specified tolerance. Higher feed rate leads
to lower and more repeatable roughness. MQL in reaming leads to high quality results in terms of
hole dimensions and surface finish. [12] The feed and speed are important process parameters to
control surface roughness, tool wear, material removal rate and hole diameter error. Thus it is
essential to employ suitable combination of cutting speed and feed so as to reduce the variations that
can affect the quality of the holes. Assignment of weights method can be used for optimizing the
proposed reaming process.
2. EXPERIMENTS AND METHODS
The main objective of this project work is to find out how various reaming parameters such
as speed, feed and allowance influence various output characteristics such as surface finish and
cylindricity while considering the manufacturing of cylindrical bores in the EHSV valve body.
Figure 1 shows the different bores in EHSV valve body.

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 31-40 © IAEME
33
Figure 1: Bores in EHSV valve body
2.1. Experimental details for proposed reaming process
The experiment was conducted on vertical milling machine as shown in figure 2. The
machine has speed settings up to 15,000 RPM, feed settings up to 30,000 mm/min. The experiments
are conducted on stainless steel 440C. TiN coated carbide reamer is used for reaming as shown in
fig. 3.
Figure 2: Experimental reaming setup
Figure 3: TiN coated carbide reamer
The number of experiments and input levels are decided based on the design of experiments
and the input parameters and their levels are presented in table 1.
Table 1: Reaming Prameters
Input Parameters Speed (RPM) Feed (mm/min) Allowance (mm)
Level 1 600 80 0.2
Level 2 800 120 0.3
Level 3 1000 160 0.4
2.2. Design of Experiments
To test the effect of these factors on a response variable, a suitable experiment is designed
such that the necessary data for testing the significance of the effects of the factors on the response
variable are collected. Identification of the response variable is the first step to be followed for the
designing of experiment. Identify the factor affecting response variables, fix the number of levels of

4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 26-30 © IAEME
each factor, form the skeleton of the experiment and define its components comprises the next step
for designing an experiment. Taguchi L9 orthogonal array as tabulated in table 2 is selected with the
help of MINITAB 16 software.
Table 2: L9 Orthogonal Array
34
Experimen
t
P1 P2 P3
1 1 1 1
2 1 2 2
3 1 3 3
4 2 1 2
5 2 2 3
6 2 3 1
7 3 1 3
8 3 2 1
9 3 3 2
2.3. Scheme of Experiments
Based on L9 orthogonal array, experiments are conducted on Stainless steel 440C with TiN
coated carbide reamer tool for different experiment levels which are shown in Table 1. Speed, feed
and allowance are selected as input variable parameters. Three varying parameters with three
different levels are taken for the purpose of design of experiments.
Table 3: Scheme of experiment
Exp.
No.
Speed
(RPM)
Feed
(mm/min)
Allowance
(mm)
1 600 80 0.2
2 600 120 0.3
3 600 160 0.4
4 800 80 0.3
5 800 120 0.4
6 800 160 0.2
7 1000 80 0.4
8 1000 120 0.2
9 1000 160 0.3

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 26-30 © IAEME
The levels are taken with the help of range of the variable parameters are chosen with the
help of GUHRING international manual for advanced machine tools. Each test is repeated three
times in order to achieve validity and accuracy. The L9 array for the experimental run is shown in
table 3.
35
2.4. Assignment of weights method
In assignment of weights method, the multi response problem is converted into a single
response problem. Here we have two responses; surface finish and cylindricity. Multi Response
performance Index (MRPI) can be calculated using the equation 1. Since MRPI is a weighted score,
optimal levels are identified based on maximum MRPI.
MRPI = W1R1 + W2R2 (1)
Where, W1 be the weight assigned to the first response R1 and W2 be the weight assigned to the first
response R2.
The weights can be determined by dividing the individual responses by the response total
value. Since here both the responses considered are having smaller the better characteristics, reverse
normalization procedure is used. That is, for each data, 1/SR and 1/ are obtained and the
corresponding WSR and W are computed using the equation 2 and 3.
WSR = (1/SR)/( 1/SR) (2)
W = (1/ )/(1/ ) (3)
3. RESULTS AND DISCUSSION
Results were obtained for surface finish and cylindricity for reaming of SS 440C
experimental blocks. MINITAB 16 software is used to perform Taguchi design of experiment.
Assignment odf weights method was performed to found the optimum combination of input
parameters.
3.1. Experimental Combinations
Three blocks of SS 440C where chosen for conducting experiments. In each block, 9 holes
were reamed based on experimental combinations obtained.
Figure 4: Experimental Blocks
All the trials where repeated thrice in order to validate the experimental results. Figure 4
shows the experimental blocks chosen for this work.

6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 26-30 © IAEME
Table 4: Reaming experimental combinations
36
Trial
No.
Bore
No.
Speed
(RPM)
Feed
(mm/min)
Allowance
(mm)
1 A1, B1, C1 600 80 0.2
2 A2, B2, C2 600 120 0.3
3 A3, B3, C3 600 160 0.4
4 A4, B4, C4 800 80 0.3
5 A5, B5, C5 800 120 0.4
6 A6, B6, C6 800 160 0.2
7 A7, B7, C7 1000 80 0.4
8 A8, B8, C8 1000 120 0.2
9 A9, B9, C9 1000 160 0.3
3.2. Experimental Results for Different Trials
The experimental results obtained by reaming experiment conducted on three blocks of SS
440C were tabulated below on table 5. The responses investigate are surface finish and cylindricity.
The experiment was conducted three times, in order to achieve repeatability. The ranges for different
parameters are set with reference to Guhrings international manual for special tools.
Table 5: Experimental results for different trials
Trial No.
Surface Roughness, SR (μm) Cylinricity, (μm)
SR1 SR2 SR3 1 2 3
1 0.59 0.61 0.59 5.3 5.32 5.32
2 0.51 0.53 0.52 6.15 6.21 6.19
3 0.54 0.54 0.55 4.34 4.34 4.35
4 0.57 0.59 0.58 7.3 7.36 7.34
5 0.53 0.53 0.52 4.08 4.08 4.09
6 0.51 0.51 0.5 2.55 2.55 2.5
7 0.69 0.71 0.7 5.06 5.1 5.09
8 0.54 0.54 0.53 4.13 4.13 4.12
9 0.51 0.53 0.51 5.24 5.32 5.31

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ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 26-30 © IAEME
37
3.3. Assignment of Weights
Table 6: Weight and MRPI
Average
SR
Average
1/SR 1/
Weights
MRPI
SR
0.6 5.31 1.67 0.19 0.1031 0.095 0.5713
0.52 6.18 1.92 0.16 0.1185 0.08 0.5601
0.54 4.34 1.85 0.23 0.1142 0.115 0.5651
0.58 7.33 1.72 0.14 0.1062 0.07 0.5731
0.53 4.08 1.89 0.25 0.1167 0.125 0.5691
0.51 2.53 1.96 0.4 0.1209 0.2 0.5672
0.7 5.08 1.42 0.2 0.0877 0.1 0.5621
0.54 4.13 1.85 0.24 0.1142 0.12 0.5572
0.52 5.29 1.92 0.19 0.1185 0.095 0.5641
Average values of each response were calculated. The weights and MRPI were calculated
using equations 1, 2 and 3. Multi Response Performance Index (MRPI) obtained can be treated as
single response problem and MRPI data is analyzed to determine the optimal level for the factors.
Level totals of MRPI values are tabulated on table 7. The weights can be determined by dividing the
individual responses by the response total value. Since here both the responses considered are having
smaller the better characteristics, reverse normalization procedure is used.
Table 7: Level Totals of MRPI
FACTORS
LEVELS
1 2 3
SPEED (A) 1.6965 1.7094 1.6834
FEED (B) 1.7065 1.6864 1.6964
ALLOWANCE (C) 1.6957 1.6973 1.6963
The optimal levels are selected based on maximum MRPI are A2, B1 and C2.

8. International Journal of Advanced Research in Engineering and Technology
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp.
1.71
1.705
1.7
1.695
1.69
1.685
1.68
1.675
MRPI CHART
1 2 3
1.6965 1.7094 1.6834
1.7065 1.6864 1.6964
1.6957 1.6973 1.6963
Figure 5: MRPI Chart
Graphical representation showing the factor effects on mean MRPI are shown in figure 5. The
optimal combination found from effect on mean MRPI are:
Speed = 800 RPM
Feed = 80 mm/min
Allowance = 0.3 mm
3.4. Confirmation Test
The confirmation test is the final step in verifying the results obtained from Taguchi’s design
approach. The optimal conditions are set for the significant factors and experiments are run under
specified reaming conditions. The results from the confirmation experiment are compared wi
predicted average based on the parameters and levels tested. The confirmation experiment is a
crucial step and is highly recommended by Taguchi to verify the experimental results.
The purpose of the confirmation experiment is to validate the conclus
experiment. Confirmation experiment is conducted using the optimal levels of the significant factors.
The confirmation test block is shown in fig. 6.
Figure 6:
1.67
SPEED
FEED
ALLOWANCE
MRPI
(IJARET), ISSN 0976
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conclusions drawn from the
Confirmation test block
– 6480(Print),
with the
ions

9. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 26-30 © IAEME
Table 8: Confirmation test results
Bore No. Surface Roughness, SR (μm) Cylindricity, (μm)
1 0.28 2.57
2 0.31 3.11
3 0.29 2.72
The confirmation test is conducted on SS 440C test block with TiN coated carbide reamer
with the optimum level of combinations found using grey relational analysis. The confirmation test
results were tabulated in table 8. In the confirmation test, the responses for which data collected are
for surface roughness and cylindricity. From the confirmation test results, it was found that while
reaming with optimal conditions by assignment of weights method, the cylindricity and surface
finish obtained were much better than expected results.
39
4. CONCLUSION
From the experiments, the optimal combination was obtained as speed (800 RPM), feed (80
mm/min), and allowance (0.3mm) using assignment of weights method. This optimum combination
was used to confirm the experiment. The confirmation test results validated the experiment.
REFERENCES
[1] F. Klocke, M. Zeis, A. Klink, D. Veselovac, 2013, Technological and economical
comparison of roughing strategies via milling, sinking-EDM, wire-EDM and ECM for
titanium and nickel based blisks, CIRP Journal of Manufacturing Science and Technology,
198-203.
[2] D. Welling, 2014, Results of surface integrity and fatigue study of Wire-EDM compared to
broanching and grinding for demanding jet engine components made of Inconel 718,
Procedia CIRP, 339-344.
[3] L. Li, Y.B. Guo, X.T. Wei, W. Li, 2013, Surface integrity characteristics in wire-EDM of
inconel 718 at different discharge energy, Procedia CIRP, 220-225.
[4] F. Klocke, D. Welling, J. Dieckmann, 2011, Comparison of grinding and Wire EDM
concerning fatigue strength an surface integrity of machined Ti6Al4V components, Procedia
Engineering, 184-189.
[5] S. Karunanidhi, M. Singaperumal, 2010, Design, analysis and simulation of magnetostrictive
actuator and its application to high dynamic servo valve, Sensors and Actuators, 185-197.
[6] Fuzhu Han, Jie Zhang, Isago Soichiro, 2007, Corner error simulation of rough cutting in wire
EDM, Precision Engineering, 331-336.
[7] D.K. Aspinwall, S.L. Soo, A.E. Berrisford, G. Walder, 2008, Workpiece Surface roughness
and integrity after WEDM of Ti-6Al-4V and Inconel 718 using minimum damage generator
technology, CIRP Annals – Manufacturing Technology, 187-190.
[8] Haruki Obara, Harutoshi Satou, Masatoshi Hatano, 2004, Fundamental study on corrosion of
cemented carbide during wire EDM, Journals of Material Processing Technology, 370-375.
[9] K.H. Ho, S.T. Newman, S. Rahimifard, R.D. Allen, 2004, State of the art in wire electric
discharge machining (WEDM), International Journal of Machine Tools Manufacture 1247-
1259
[10] B. Bojorquez, R.T. Marloth, O.S. Es-Said, 2002, Formation of a crater in the workpiece on an
electric discharge machine, Engineering failure Analysis, 93-97.

10. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print),
ISSN 0976 – 6499(Online) Volume 5, Issue 9, September (2014), pp. 26-30 © IAEME
[11] P. Muller, G. Genta, G. Barbato, L. De Chiffre, R. Levi, 2012, Reaming process
improvement and control: An application of statistical engineering, CIRP Journal of
Manufacturing Science and Technology, 196-201
[12] J. Pradeep Kumar, P. Packiaraj, 2012, Effect of drilling parameters on the surface roughness,
tool wear, material removal rate and hole diameter error in drilling of OHN, International
Journal of Avanced Engineering Research and Studies, 150-154
[13] Leonardo De Chiffre, Guide Tosello, Miroslav Piska,Pavel Muller, 2009, Investigation on
capability of the reaming process using minimal quantity lubrication, CIRP journal of
Manufacturing Science and Technology, 47-54.
[14] GUHRING International Manual on advanced machine tools, 9th edition, 2006.
[15] K. Krishnaiah, P. Shahabudeen, 2012, Applied design of experiments and Taguchi methods,
40
PHI learning Private Limited,
[16] H. Dagnall M.A., 1996, Let’s Talk Roundness, Taylor Hobson Limited.
[17] Papers on Precision engineering, SERC School on ‘Precision Engineering’, 2001, Indian
Institute of Technology Madras, Chennai, December 4-14
[18] R. Paneerselvam, 2013, Research Methodology, PHI Learning Private Limited.
[19] R. Paneerselvam, 2012, Production and Operations Management, PHI Learning Private
Limited.
[20] A. Parshuramulu, K. Buschaiah and P. Laxminarayana, “A Study on Influence of Polarity on
the Machining Characteristics of Sinker EDM”, International Journal of Advanced Research
in Engineering Technology (IJARET), Volume 4, Issue 3, 2013, pp. 158 - 162, ISSN Print:
0976-6480, ISSN Online: 0976-6499.
[21] S V Subrahmanyam and M. M. M. Sarcar, “Parametric Optimization for Cutting Speed – A
Statistical Regression Modeling for WEDM”, International Journal of Advanced Research in
Engineering Technology (IJARET), Volume 4, Issue 1, 2013, pp. 142 - 150, ISSN Print:
0976-6480, ISSN Online: 0976-6499.
[22] M Manohar, Jomy Joseph, T Selvaraj and D Sivakumar, “Development of Models using
Genetic Programming for Turning Inconel 718 with Coated Carbide Tools”, International
Journal of Design and Manufacturing Technology (IJDMT), Volume 4, Issue 1, 2013,
pp. 1 - 13, ISSN Print: 0976 – 6995, ISSN Online: 0976 – 7002.