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Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9208-9216 9208 
 

www.etasr.com Le: Multi-Criteria Decision Making in the Milling Process Using the PARIS Method 

 

Multi-Criteria Decision Making in the Milling 

Process Using the PARIS Method 
 

Hong Ky Le 

Vinh Long University of Technology Education 

Vinh Long, Vietnam 

kylh@vlute.edu.vn 
 

Received: 8 July 2022 | Revised: 25 July 2022 | Accepted: 25 July 2022 

 

Abstract-The Multi-Criteria Decision-Making (MCDM) process 

of milling SNCM439 steel is presented in this study. In this 

experimental study, 3 cutting tool parameters, namely the 

number of pieces, cutting piece material, and tip radius were 

considered and 3 cutting mode parameters, i.e. cutting speed, 

feed rate, and depth of cut changed in each experiment. SR and 

MRR are selected as the output parameters of the milling 

process. The PARIS method was used for MCDM, in which, the 

weights of SR and MRR were determined by 3 methods, namely 

AW, EW, and MW. Twenty-seven sets of ranking results for 27 

alternatives (experiments) are presented. The GINI index was 

used to evaluate the stability of ranking alternatives. The results 

have determined the value of 6 input parameters to ensure the 

minimum SR and the maximum MRR simultaneously. 

Keywords-MCDM; PARIS; average weight; entropy weight; 

Merec weight; GINI index; milling 

I. INTRODUCTION  

Milling the plane with a face milling cutter is a machining 
method that gives the highest productivity of all cutting 
machining methods, because it has many teeth simultaneously 
involved in cutting and a tool with a large diameter can be 
chosen [1-3]. Therefore, this method is increasingly used in 
machine manufacturing. Thanks to the development of 
machine tools as well as cutting tool manufacturing 
technology, the accuracy of this method is increasingly 
improved. This method is even used instead of grinding when it 
is necessary to machine surfaces that require high precision. In 
addition, the residual stress on the surface layer of the part 
during milling is usually compressive residual stress, whereas 
the residual stress on the surface layer during grinding is 
usually tensile residual stress. This is also the advantage of 
milling over the grinding method. Among many criteria to 
evaluate the machining process, such as MRR, surface 
hardness, cutting force, cutting heat, etc., SR and MRR are the 
two most used parameters in published documents. This can be 
easily understood because MRR is an important parameter to 
evaluate cutting productivity, while SR is a parameter that has 
a great influence on the workability as well as the life of the 
product. On the other hand, determining the value of SR and 
MRR is also quite simple, specifically an SR measuring device 
is quite more popular than a force measuring device or a heat 
measuring device, and MRR can be calculated from simple 

math formulas. As with most machining processes, it is 
desirable to have minimum SR and maximum MRR when 
milling the plane with a face mill. However, these requirements 
cannot be achieved simultaneously with each specific 
machining condition. Some examples to support this statement 
follow. In [4], when performing 27 tests of milling SCM440 
steel, the one with the smallest SR was also the one with the 
smallest MRR. When performing 9 tests for milling 060A4 
steel, the one with the smallest SR is had a very small MRR 
[5]. Among 27 SKD11 steel milling experiments, the one with 
the smallest SR almost had the smallest MRR [6], etc. Thus, in 
cases like these it is necessary to define an experiment where 
SR is considered smallest and MRR is considered maximum, 
i.e. an MCDM [4-6] problem. There are various mathematical 
methods that support MCDM such as: SAW, WASPAS, 
TOPSIS, VIKOR, MOORA, COPRAS, PIV, PSI, EDAS, 
MARCOS, CODAS, WASPAS, WPAS, etc. These methods 
have been widely applied to MCDM in many different fields. 
The common feature of these methods is that each method 
gives only one set of ranking results for the alternatives. 

The PARIS method was first proposed in 2020 by Ardil [7]. 
PARIS is also an MCDM method, but, unlike the above 
techniques, it performs threefold data normalization in 3 
different ways. In addition, for each data normalization 
method, the ranking of the alternatives is performed in 3 stages. 
Thus, when applying this method, 9 different ratings will be 
conducted for the alternatives. In the next section of this paper, 
this method will be presented in detail. This method has been 
applied to make multi-criteria decisions in some specific cases 
such as: When deciding in choosing 1 of 6 aircraft types, each 
aircraft is evaluated through 7 criteria. The PARIS method was 
applied to accomplish this in [7]. In this study, two methods, 
i.e. AW and EW were used to determine the weights for 7 
criteria. The TOPSIS method was also used and compared with 
the PARIS method. When using the PARIS method with two 
different weighting methods (AW and EW) it gave 18 ranking 
options. When using the TOPSIS method with two different 
weighting methods two ranking options were proposed. An 
interesting result was obtained that all 20 ranking options 
identified the best aircraft according to the 7 given criteria. 
Besides, Ardil also used the PARIS method [8] to decide which 
one of the 3 types of military aircraft to choose. In this case, 
each aircraft is evaluated on 7 criteria. AW and EW were again 

Corresponding author: Hong Ky Le



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used to determine the weights of the criteria and TOPSIS was 
also used and compared with the PARIS method. The 
calculated results showed that all 20 ranking options (including 
18 options of PARIS and 2 options of TOPSIS) identified the 
same best aircraft. In [9], the PARIS method was also used to 
select 1 out of 5 software candidates, considering 8 criteria. In 
total, there were 31 sub-criteria out of which 8 were applied. In 
addition, 3 different sets of weights that are random numbers 
(RN) have been assigned to the criteria. The calculated results 
showed 27 rating options. In particular, the different best 
alternatives depended on the random weights assigned to the 
criteria. 

The above results show that the use of PARIS method is 
quite effective. However, the PARIS method has only been 
used in the mentioned studies. Up to now, and to the best of our 
knowledge, there have been no studies using this method in 
MCDM for the milling process and mechanical processing in 
general. AW, EW, and RN methods were used to determine the 
weights for the criteria in the above studies when applying the 
PARIS method. This is understandable because AW is the 
simplest method to determine the weights for criteria where the 
weights of the criteria are equal, and EW is a method with high 
accuracy that has been widely used. Its use is recommended in 
MCDM [10]. The RN method was used because out of the 31 
criteria for software evaluation, there are both qualitative and 
quantitative criteria. However, for quantitative criteria it is not 
necessary to use this method. The MW weighting method was 
first proposed in 2021 [11]. It has been used in several studies 
to determine weights in MCDM [12, 13]. However, this 
method has not been used to determine weights for the criteria 
of any milling process. Therefore, the use of the MW method 
for determining the weights for the criteria of the milling 
process along with the two methods already used (AW and 
EW) ensures the novelty of the current study. The use of 3 
methods of determining weights in a study is the basis for 
assessing the stability in determining the best solution. 

SNCM439 steel (according to JIS standard - Japan) is a 
high-alloy steel and products like gears, wood cutters, dies, etc. 
are usually made from it. This steel is equivalent to some steels 
according to other standards such as, AISI - 4340, EN - 
36CrNiMo4, BS - EN24, JIS - SNCM439, DIN - 150Cr14, 
GOST - 9CrSi (or 9XC or 9HS or 9KHS). There have been a 
few studies regarding the milling of this steel (or equivalent 
steels). In [14], the authors investigated the influence of the 
parameters of the MQL-type cooling lubrication on SR when 
hard milling of 9CrSi steel. In [15], the Response Surface 
Method (RSM) and an Artificial Neural Network (ANN) model 
were combined to predict the value of tool wear and cutting 
force for the dry milling of EN24 steel. In [16], the shear force 
and friction force were investigated when milling EN24 steel 
with different cooling lubrication conditions. In [17], the 
optimal values of cutting speed, feed rate, and depth of cut 
were determined to ensure minimum SR when milling En24 
steel. The influence of cutting speed, feed rate, and depth of cut 
on SR on cutting temperature when hard milling AISI-4340 
steel were investigated in [18]. In [19], it was determined that 
the value of cutting speed, feed rate, and depth of cut improve 
the surface hardness when milling AISI-4340 steel. Research 
on milling steel SNCM439 (or equivalent steels) has been 

conducted in a number of studies as described above. However, 
to date, there has not been any research done in MCDM when 
machining this steel. This is the reason that this steel was 
chosen as the research object in this paper. 

Like the SR parameter, the MRR is a very common 
parameter used to evaluate the milling process. This parameter 
reflects the processing capacity. Considering both SR and 
MRR in a study makes both economic and technical 
implications. That is why this study has selected both SR and 
MRR as the criteria to evaluate the milling process. Besides, 
the three cutting parameters (cutting speed, feed rate, and depth 
of cut) that have been investigated in many studies, the 
parameters of the cutting tool (number of inserts, cutting tool 
material, and nose radius) are also parameters that have a great 
influence on the surface roughness during milling [20-22]. 
However, until now, no study has been found that considers all 
6 of these parameters during the milling process. Therefore, the 
consideration of all these 6 parameters is also a novelty of this 
work. 

This study will conduct SNCM439 steel milling 
experiments. In each experiment, 6 parameters will be changed 
including cutting speed, feed rate, depth of cut, number of 
inserts, insert material, and nose radius. SR and MRR were 
selected as the two output criteria. PARIS method is used for 
MCDM with 3 weighting methods including AW, EW, and 
MW. 

II. THE PARIS METHOD 

The PARIS method is performed according to the following 
steps [7]. 

Step 1: Building of the decision matrix. 

� =  �
��� ��� ��� ��	��� ��� ��� ��	�
� �
� �
� �
	��� ��� ��� ��	 �    (1) 

In which: m is the number of options, i = 1, 2, …, m and n 
is the number of criteria, j= 1, 2, …, n. 

If xij is negative then do the calculation x’ij = xij = min(xij), 
then x’ij is used to calculate the next steps. 

Step 2: Normalizing the decision matrix. 

Normalizing way 1 (Vector normalization): 


� =  �
��∑ �
���
��  If j is the criterion, the bigger the better (2) 

� =  1 − �
��∑ �
���
��  If j is the criterion, the smaller the better (3) 

Normalizing way 2 (Linear normalization): 


� =  �
������  If j is the criterion, the bigger the better (4) 



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� =  ���
	�
�  If j is the criterion, the smaller the better (5) 
Normalizing way 3 (Max - Min linear normalization): 


� =  �
� − ���
	����� − ���
	  If j is the criterion, the bigger the better (6) 

� =  ����� − �
������ − ���
	  If j is the criterion, the smaller the better (7) 

Step 3: Calculating of the weighted normalized value: �
� = �� ∙ 
�     (8) 
Step 4: Summarizing the weighted normalized values as: �
� = ∑ �� ∙ 
�	���     (9) 

where i = 1, 2,… m; j = 1, 2,..., n. 

Step 5: Rank the alternatives. The solution with the largest 
value of �
�  is the best solution. 

Step 6: Identify the elements of the reference ideal solution: 

��∗ = ���∗, … , ��∗� =  �� !�
  �
�  �" ∈ $%, � &'
 �
��" ∈ (%�    (10) 
where B represents a criterion as large as possible, C represents 
a criterion as small as possible. 

Step 7: Calculate the distance from the reference ideal 
solution: �
∗ = ∑ ���∗ − �
� %	���     (11) 

Step 8: Rank the alternatives according to the principle that 

the one with the smallest value of πi is the best one. 

Step 9: Calculate the distance from the alternatives to the 
ideal solution: 

)
 = ���
� − �
�,��� %� + ��
∗ − �
∗,�
	 %�    (12) 
Step 10: Rank the alternatives according to the principle 

that the one with the smallest Ri value is the best one. 

III. METHODS OF DETERMINING WEIGHTS 

A. The Average Weight Method 

AW is determined according to the following formula [23]: 

+� = �	    (13) 
where n is the number of criteria. 

B. The Entropy Weighted Method 

EW is determined according to the following steps [10]. 

Step 1: Determine the normalized values for the indicators: 

,ij = �ij�-. �ij/0123     (14) 

where xij is the value of criterion j corresponding to option i 
and m is the number of alternatives. 

Step 2: Calculate the value of the Entropy measure for each 
indicator with: 

( ) ( )
j ij ij1

ij ij1 1

ln(p )

1 ln 1

m

i

m m

i i

me p

p p

=

= =

 = − ⋅ − 

− ⋅ −



 
    (15) 

Step 3: Calculate the weight for each indicator: 

+� = �4�56∑ ��4�56%0623     (16) 
C. The MEREC Weight Method 

MW is determined according to the following steps [11]:  

Step 1: Is similar to step 1 of the PARIS method.  

Step 2: Calculate the normalized values according to: 

ℎ
� =  �
	�16�16   If j is the criterion, the bigger the better. (17) 
ℎ
� =  �16����16   If j is the criterion, the smaller the better (18) 

Step 3: Calculate the overall efficiency of the alternatives 
according to: 

8
 =  9' :1 + ;�	 ∑ <='�ℎ
� %<	� >?    (19) 
Step 4: Calculate the performance of the alternatives 

according to: 

8
�@ =  9' :1 + ;�	 ∑ <='�ℎ
� %<	A,AB� >?    (20) 
Step 5: Calculate the absolute value of the deviations 

according to: C� =  ∑ <8
�@ − 8
 <�
     (21) 
Step 6: Calculate the weight for the criteria according to:  

+� =  D6∑ DE0E     (22) 
IV. MILLING EXPERIMENT 

A. Experimental Design 

Experiments were carried out on a 3-axis machining center. 
The values of the 6 input parameters are presented in Table I 
[1, 24]. As the number of inserts varies in each experiment, 3 
different types of inserts have been used. In addition, each type 
of tool head has several insert positions of 2, 3, and 4. All 3 
types of cutters have a diameter of 40mm. The basic 
geometrical parameters of the selected insert types are the 
same. Specifically, the main cutting angle is 90

0
, the main 

cutting-edge length is 10mm, and the blade width is 6.8mm 
[24]. The Taguchi method was used for the experimental 
design due to its advantages [25, 26]. In this experiment, an 
experimental matrix of 27 experiments was designed (Table II).  



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TABLE I.  INPUT PARAMETERS 

Parameter Symbol Unit 
Value at level 

1 2 3 

Number of insert N - 2 3 4 

Insert material M - TiN TiCN TiAlN 

Nose radius r mm 0.3 0.5 0.8 

Cutting speed vc m/min 120 150 180 

Feed rate vf mm/min 300 400 500 

Depth of cut ap mm 0.2 0.35 0.5 

TABLE II.  EXPERIMENTAL MATRIX AND RESULTS 

Trial N M 
r 

(mm) 

vc 

(m/min) 

vf 

(mm/min) 

ap 

(mm) 

MRR 

(mm
3
/min) 

SR 

(µµµµm) 

1 2 TiN 0.3 120 300 0.2 2400 2.287 

2 2 TiN 0.3 120 400 0.35 5600 3.152 

3 2 TiN 0.3 120 500 0.5 10000 4.017 

4 2 TiCN 0.5 150 300 0.2 2400 1.377 

5 2 TiCN 0.5 150 400 0.35 5600 2.242 

6 2 TiCN 0.5 150 500 0.5 10000 3.107 

7 2 TiAlN 0.8 180 300 0.2 2400 0.490 

8 2 TiAlN 0.8 180 400 0.35 5600 1.240 

9 2 TiAlN 0.8 180 500 0.5 10000 2.105 

10 3 TiN 0.5 180 300 0.35 4200 0.245 

11 3 TiN 0.5 180 400 0.5 8000 0.793 

12 3 TiN 0.5 180 500 0.2 4000 1.163 

13 3 TiCN 0.8 120 300 0.35 4200 1.104 

14 3 TiCN 0.8 120 400 0.5 8000 1.969 

15 3 TiCN 0.8 120 500 0.2 4000 2.339 

16 3 TiAlN 0.3 150 300 0.35 4200 0.838 

17 3 TiAlN 0.3 150 400 0.5 8000 1.703 

18 3 TiAlN 0.3 150 500 0.2 4000 2.073 

19 4 TiN 0.8 150 300 0.5 6000 0.345 

20 4 TiN 0.8 150 400 0.2 3200 0.456 

21 4 TiN 0.8 150 500 0.35 7000 0.890 

22 4 TiCN 0.3 180 300 0.5 6000 0.611 

23 4 TiCN 0.3 180 400 0.2 3200 0.241 

24 4 TiCN 0.3 180 500 0.35 7000 0.624 

25 4 TiAlN 0.5 120 300 0.5 6000 0.657 

26 4 TiAlN 0.5 120 400 0.2 3200 1.027 

27 4 TiAlN 0.5 120 500 0.35 7000 1.892 

 

B. Results and Discussion 

The SR for each experiment can be seen presented in Table 
II. These values are the mean values of at least 3 consecutive 
measurements. In addition, the MRR at each experiment is also 
been summarized in Table II. The values are calculated by (23), 
where vf, ap and bw are the feed rate, the depth of cut, and the 
wide cut respectively. F)) =  GH ∙ !I ∙ JK     (23) 

The extent and influence of the parameters on SR are 
shown in Figure 1. From this graph, it is shown that: 

• The number of inserts, cutting speed, and feed rate have a 
great influence on SR. The nose radius and depth of cut also 
affect the SR, but to a lesser extent than the 3 mentioned 
above parameters. The insert material has no significant 
effect on SR. 

• When the number of insert increases, the SR decreases. 
This can be explained by the fact that as the number of 
inserts increases, each area of the machined surface is cut 
more than once. That means that after a insert cuts off a 

layer of the material, the metal layer on the surface of the 
part will be elastically deformed. This metal is then 
removed by other cuttings, which causes the SR to 
decrease. 

• As the cutting speed increases, the cutting tool rotates at a 
faster speed. Then a point on the surface of the workpiece 
will be repeatedly cut by the cutting edges, even the 
undulations caused by plastic deformation will be 
eliminated, which leads to a reduced SR. The case is similar 
with the increasing of the number of inserts discussed 
above. 

• As the feed rate increases, the time the cutting tool is in 
contact between an area of the part surface and the cutting 
edge decreases, causing plastic layers of metal on the 
surface to not be removed, leading to an increase in SR. 
Increasing the nose radius will cause the SR to decrease. It 
can be understood that the height of the surface undulation 
is inversely proportional to the nose radius, as discussed in 
[27]. Furthermore, the large SR at large feed rates and small 
nose radius are also consistent with the SR calculation 
formula used in some studies [27]: )� = 1000 ∙ 0.0321 ∙ GH�/
 

 

 

Fig. 1.  Main effects plot for surface roughness. 

From Figure 1, if the SR has a small value, choose a large 
cutting speed, a small feed rate, and a small depth of cut. 
However, according to (23), when the feed rate and cutting 
depth are small, the MRR will also be small, which is 
undesirable. Therefore, choosing the value of the cutting 
parameters to ensure that the SR is small and the MRR is large, 
it is necessary to make the right decisions. This right decision 
can be made with a MCDM method. In this problem, the 
PARIS method will be used.  

V. MULTI-CRITERIA DECISION MAKING 

A. Determining the Weights of the Criteria  

Equation (1) is used to build the decision matrix. The last 
two columns in Table II are the decision matrix. Equation (13) 
was applied to determine the weights of the criteria according 
to the AW method. In addition, (14)-(16) are used to determine 
the weights for the criteria according to the EW method. 
Equations (17)-(22) determine the weights of the criteria of the 
MW method. The results are shown in Table III. 



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TABLE III.  CRITERIA WEIGHTS 

Method Ra MRR 

AW 0.5 0.5 

EW 0.6859 0.3141 

MW 0.3663 0.6337 
 

B. Applying the PARIS Method 

Equations (2) and (3) are used to normalize the matrix in 
way 1. Equations (4) and (5) are applied to normalize the 
matrix in way 2. Equations (6) and (7) are used to normalize 
the matrix in way 3. The results are presented in Table V.  

TABLE IV.  VALUE OF Z*J 

Normalization SR MRR 

Way 1 0.255 0.200 

Way 2 0.030 0.500 

Way 3 0.000 0.500 
 

To rank the alternatives for weight calculation according to 
the AW method we apply (8) to calculate the weighted 
normalized value (zij) and (9) to calculate the weighted 

normalized sum (π
ω

i). The results are presented in Table VI. 
The results of ranking the alternatives according to the value of 

π
ω

i are also presented in this Table. Equation (10) was applied 
to determine the factors of the ideal solution (z

*
j) and the results 

are presented in Table IV. Equation (11) is used to determine 

the distance from the reference ideal solution (πi). The results 
are presented in Table VII. The results of ranking the 

alternatives according to the value of π
*

i are also presented in 
this Table. The distance from the alternatives to the ideal 
solution (Ri) is calculated by (12). The results are presented in 

Table VIII. The results of ranking options according to the 
value of Ri are also shown in this Table.  

TABLE V.  NORMALIZED MATRICES 

Trial. 
Way 1 Way 2 Way 3 

SR MRR SR MRR SR MRR 

1 0.721 0.096 0.105 0.240 0.458 0.000 

2 0.616 0.224 0.076 0.560 0.229 0.421 

3 0.511 0.400 0.060 1.000 0.000 1.000 

4 0.832 0.096 0.175 0.240 0.699 0.000 

5 0.727 0.224 0.107 0.560 0.470 0.421 

6 0.622 0.400 0.078 1.000 0.241 1.000 

7 0.940 0.096 0.492 0.240 0.934 0.000 

8 0.849 0.224 0.194 0.560 0.735 0.421 

9 0.744 0.400 0.114 1.000 0.506 1.000 

10 0.970 0.168 0.984 0.420 0.999 0.237 

11 0.903 0.320 0.304 0.800 0.854 0.737 

12 0.858 0.160 0.207 0.400 0.756 0.211 

13 0.866 0.168 0.218 0.420 0.771 0.237 

14 0.760 0.320 0.122 0.800 0.542 0.737 

15 0.715 0.160 0.103 0.400 0.444 0.211 

16 0.898 0.168 0.288 0.420 0.842 0.237 

17 0.793 0.320 0.142 0.800 0.613 0.737 

18 0.747 0.160 0.116 0.400 0.515 0.211 

19 0.958 0.240 0.699 0.600 0.972 0.474 

20 0.944 0.128 0.529 0.320 0.943 0.105 

21 0.892 0.280 0.271 0.700 0.828 0.605 

22 0.926 0.240 0.394 0.600 0.902 0.474 

23 0.971 0.128 1.000 0.320 1.000 0.105 

24 0.924 0.280 0.386 0.700 0.899 0.605 

25 0.920 0.240 0.367 0.600 0.890 0.474 

26 0.875 0.128 0.235 0.320 0.792 0.105 

27 0.770 0.280 0.127 0.700 0.563 0.605 
 

TABLE VI.  SOME PARAMETERS IN PARIS RANKED BY THE VALUE OF πωi 

Trial 

Way 1 Way 2 Way 3 

zij 
ππππ

ωωωω
i Rank 

zij 
ππππ

ωωωω
i Rank 

zij 
ππππ

ωωωω
i Rank 

SR MRR SR MRR SR MRR 

1 0.361 0.048 0.409 27 0.053 0.120 0.173 27 0.229 0.000 0.229 27 

2 0.308 0.112 0.420 26 0.038 0.280 0.318 21 0.115 0.211 0.325 26 

3 0.255 0.200 0.455 23 0.030 0.500 0.530 8 0.000 0.500 0.500 18 

4 0.416 0.048 0.464 22 0.088 0.120 0.208 26 0.350 0.000 0.350 24 

5 0.363 0.112 0.476 21 0.054 0.280 0.334 19 0.235 0.211 0.446 22 

6 0.311 0.200 0.511 18 0.039 0.500 0.539 7 0.120 0.500 0.620 10 

7 0.470 0.048 0.518 16 0.246 0.120 0.366 17 0.467 0.000 0.467 20 

8 0.424 0.112 0.537 12 0.097 0.280 0.377 16 0.368 0.211 0.578 13 

9 0.372 0.200 0.572 7 0.057 0.500 0.557 4 0.253 0.500 0.753 2 

10 0.485 0.084 0.569 8 0.492 0.210 0.702 1 0.499 0.118 0.618 11 

11 0.452 0.160 0.612 1 0.152 0.400 0.552 5 0.427 0.368 0.795 1 

12 0.429 0.080 0.509 19 0.104 0.200 0.304 22 0.378 0.105 0.483 19 

13 0.433 0.084 0.517 17 0.109 0.210 0.319 20 0.386 0.118 0.504 17 

14 0.380 0.160 0.540 11 0.061 0.400 0.461 13 0.271 0.368 0.640 9 

15 0.358 0.080 0.438 25 0.052 0.200 0.252 25 0.222 0.105 0.327 25 

16 0.449 0.084 0.533 14 0.144 0.210 0.354 18 0.421 0.118 0.539 15 

17 0.396 0.160 0.556 9 0.071 0.400 0.471 12 0.306 0.368 0.675 8 

18 0.374 0.080 0.454 24 0.058 0.200 0.258 24 0.257 0.105 0.363 23 

19 0.479 0.120 0.599 3 0.349 0.300 0.649 3 0.486 0.237 0.723 4 

20 0.472 0.064 0.536 13 0.264 0.160 0.424 14 0.472 0.053 0.524 16 

21 0.446 0.140 0.586 4 0.135 0.350 0.485 10 0.414 0.303 0.717 5 

22 0.463 0.120 0.583 5 0.197 0.300 0.497 9 0.451 0.237 0.688 6 

23 0.485 0.064 0.549 10 0.500 0.160 0.660 2 0.500 0.053 0.553 14 

24 0.462 0.140 0.602 2 0.193 0.350 0.543 6 0.449 0.303 0.752 3 

25 0.460 0.120 0.580 6 0.183 0.300 0.483 11 0.445 0.237 0.682 7 

26 0.437 0.064 0.501 20 0.117 0.160 0.277 23 0.396 0.053 0.449 21 

27 0.385 0.140 0.525 15 0.064 0.350 0.414 15 0.281 0.303 0.584 12 
 



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TABLE VII.  π*i VALUES AND RATINGS 

Trial 
Way 1 Way 2 Way 3 

ππππ
*

i Rank ππππ
*

i Rank ππππ
*

i Rank 

1 0.047 27 0.357 27 0.271 27 

2 0.035 26 0.212 21 0.175 26 

3 0.000 23 0.000 8 0.000 18 

4 -0.009 22 0.322 26 0.150 24 

5 -0.020 21 0.196 19 0.054 22 

6 -0.055 18 -0.009 7 -0.120 11 

7 -0.063 16 0.164 17 0.033 20 

8 -0.081 12 0.153 16 -0.078 13 

9 -0.116 7 -0.027 4 -0.253 2 

10 -0.114 8 -0.172 1 -0.118 6 

11 -0.156 1 -0.022 5 -0.295 1 

12 -0.054 19 0.226 22 0.017 19 

13 -0.061 17 0.211 20 -0.004 17 

14 -0.085 11 0.069 13 -0.140 10 

15 0.018 25 0.278 25 0.173 25 

16 -0.078 14 0.176 18 -0.039 15 

17 -0.101 9 0.059 12 -0.175 9 

18 0.002 24 0.272 24 0.137 23 

19 -0.144 3 -0.119 3 -0.223 4 

20 -0.081 13 0.106 14 -0.024 16 

21 -0.130 4 0.045 10 -0.217 5 

22 -0.127 5 0.033 9 -0.188 7 

23 -0.094 10 -0.130 2 -0.053 14 

24 -0.147 2 -0.013 6 -0.252 3 

25 -0.125 6 0.047 11 -0.182 8 

26 -0.046 20 0.253 23 0.051 21 

27 -0.069 15 0.116 15 -0.084 12 

 

TABLE VIII.  Ri VALUES AND RATINGS 

Trial 
Way 1 Way 2 Way 3 

Ri Rank Ri Rank Ri Rank 

1 0.287 27 0.748 27 0.976 27 

2 0.271 26 0.543 21 0.750 18 

3 0.221 23 0.243 8 0.418 3 

4 0.209 22 0.699 26 0.912 26 

5 0.193 21 0.521 19 0.681 14 

6 0.143 18 0.231 7 0.343 2 

7 0.132 16 0.475 17 0.860 25 

8 0.106 12 0.459 16 0.624 13 

9 0.056 7 0.204 4 0.298 1 

10 0.060 8 0.000 1 0.700 15 

11 0.000 1 0.212 5 0.427 4 

12 0.145 19 0.563 22 0.757 19 

13 0.134 17 0.541 20 0.737 17 

14 0.101 11 0.340 13 0.454 6 

15 0.246 25 0.637 25 0.834 24 

16 0.111 14 0.492 18 0.724 16 

17 0.078 9 0.327 12 0.444 5 

18 0.223 24 0.627 24 0.814 22 

19 0.018 3 0.074 3 0.563 10 

20 0.107 13 0.393 14 0.791 21 

21 0.037 4 0.306 10 0.499 8 

22 0.041 5 0.289 9 0.569 11 

23 0.088 10 0.059 2 0.781 20 

24 0.014 2 0.224 6 0.495 7 

25 0.045 6 0.309 11 0.570 12 

26 0.156 20 0.600 23 0.820 23 

27 0.123 15 0.408 15 0.536 9 

 

TABLE IX.  RANKING WHEN THE WEIGHTS ARE DETERMINED WITH THE EW METHOD 

Trial 
Ranking by value of ππππ

ωωωω
i Ranking by value of ππππ

*
i Ranking by value of Ri 

Way 1 Way 2 Way 3 Way 1 Way 2 Way 3 Way 1 Way 2 Way 3 

1 25 27 26 25 27 25 25 27 27 

2 26 23 27 26 23 27 26 23 24 

3 27 13 25 27 13 26 27 13 13 

4 20 26 20 20 2 20 20 26 26 

5 21 22 22 21 22 22 21 22 17 

6 23 12 21 23 12 21 23 12 3 

7 10 9 13 10 9 13 10 9 22 

8 12 17 14 12 17 14 12 17 12 

9 17 11 10 17 11 10 17 11 1 

10 4 1 5 2 1 5 2 1 14 

11 3 6 1 4 6 1 4 6 2 

12 16 20 17 15 20 17 15 20 18 

13 13 19 15 13 19 15 13 19 16 

14 18 15 16 18 15 16 18 15 5 

15 24 25 24 24 25 24 24 25 25 

16 11 16 11 11 16 11 11 16 15 

17 14 14 12 16 14 12 16 14 4 

18 22 24 23 22 24 23 22 24 23 

19 1 3 2 1 3 2 1 3 8 

20 9 5 9 9 5 9 9 5 20 

21 8 10 7 8 10 7 8 10 7 

22 5 7 4 6 7 4 6 7 9 

23 7 2 8 5 2 8 5 2 19 

24 2 4 3 3 4 3 3 4 6 

25 6 8 6 7 8 6 7 8 10 

26 15 21 18 14 21 19 14 21 21 

27 19 18 19 19 18 18 19 18 11 

 

 



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TABLE X.  RANKING WHEN THE WEIGHTS ARE DETERMINED WITH THE MW METHOD 

Trial 
Ranking by value of ππππ

ωωωω
i Ranking by value of ππππ

*
i Ranking by value of Ri 

Way 1 Way 2 Way 3 Way 1 Way 2 Way 3 Way 1 Way 2 Way 3 

1 27 27 27 27 27 27 27 27 27 

2 24 18 22 24 18 22 24 18 15 

3 14 3 9 14 3 10 14 3 3 

4 25 26 26 25 26 26 25 26 26 

5 20 17 16 20 17 17 20 17 14 

6 10 2 3 9 2 3 10 2 2 

7 21 21 23 21 21 23 21 21 25 

8 13 15 13 13 15 14 13 15 13 

9 2 1 1 2 1 1 2 1 1 

10 11 5 14 11 5 15 11 5 16 

11 1 6 2 1 6 2 1 6 4 

12 19 22 20 19 22 8 19 22 19 

13 18 20 18 18 20 19 18 20 18 

14 9 10 7 10 10 7 9 10 6 

15 26 24 25 26 25 25 26 24 23 

16 16 19 15 16 19 16 16 19 17 

17 6 9 5 6 9 5 6 9 5 

18 23 23 24 23 23 24 23 23 21 

19 5 4 8 5 4 9 5 4 10 

20 17 16 19 17 16 20 17 16 22 

21 4 11 6 4 11 6 4 11 8 

22 7 12 10 7 12 11 7 12 11 

23 15 8 17 15 8 18 15 8 20 

24 3 7 4 3 7 4 3 7 7 

25 8 13 11 8 13 12 8 13 12 

26 22 25 21 22 24 21 22 25 24 

27 12 14 12 12 14 13 12 14 9 

 

The ranking results in Tables V-X show 27 different 
ranking options. From these results it is shown that:  

• 22/27 times experiment #1 was determined to be the worst. 
In this experiment, MRR = 2400mm

3
/min was one of the 3 

smallest values in Table II (equal to the MRR in 

experiments #4 and #7). In addition, Ra = 2.287µm is very 
large compared to the surface texture in other experiments 
(only smaller than the surface texture in 4 experiments: #2, 
#3, #5, and #15). That allows the claim that the experiment 
#1 is the worst to be entirely reasonable. 

• 8/27 times determined experiment #9, 6/27 times 
determined experiment #10, 10/27 times determined 
experiment #11, and 3/27 times determined experiment #19 
as the best. Thus, determining which experiment is the best 
would not be achieved if the work stopped here. To 
determine the best experiment, in addition to the ranking 
results, it is also necessary to add the stability of the ratings. 
In this study, the GINI index value will be used to 
determine the stability in ranking the alternatives [29]. The 
GINI index value is determined by [29, 30]: 

QR)S =  TR�4�S;U/4VWXY RU∙Z/SV> ∑ ∑ |)\ − )] |U]�\-�U4�\��     (24) 
where m is the number of options, z is the number of MCDM 
methods used, Rh and Rl are the ranking values of the 

alternatives of the decision method h and l, and D(R) ∈[0,1]. 
When D(R) = 0, the rank of an alternative is the same when 
ranking by different methods. In contrast, when D(R) = 1, the 
ranking of the alternatives is most different when using 
different ranking methods. When comparing two alternatives, 

the one with the smaller GINI index value is the better one. 
Equation (24) has been applied to calculate the GINI index 
value for the data in Tables V-X. The results are presented in 
Table XI. 

TABLE XI.  GINI INDEX VALUE OF THE ALTERNATIVES 

Experiment GINI index Experiment GINI index 

1 0.002536 15 0.003381 

2 0.018808 16 0.015427 

3 0.048605 17 0.017751 

4 0.018174 18 0.004861 

5 0.012468 19 0.013314 

6 0.040152 20 0.019231 

7 0.01754 21 0.019019 

8 0.014159 22 0.015216 

9 0.019442 23 0.040997 

10 0.032967 24 0.012046 

11 0.016272 25 0.015216 

12 0.018597 26 0.016061 

13 0.014582 27 0.011834 

14 0.017117   

 

The results in Table XI show that: 

• In experiment #1, the minimum GINI index value is 
0.002536. This proves that experiment #1 has the highest 
stability when ranking in different times. Up to 22/27 
options confirmed this experiment as the worst (ranked 
27th), 4/27 options indicate that this experiment is the 
second worst (ranked 26), and 1/27 indicates that this 
experiment is the third worst (ranked 25). On the other 
hand, 27th or 26th or 25th ranking is very close. That 
proves that experiment #1 has the highest stability when 
ranking according to different options. 



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• In experiment #3, the largest GINI index value was 
0.048605, proving that this experiment has the lowest rank 
stability when ranking according to the alternatives. 
According to the data in Tables VI, VIII-XI, experiment #3 
came 5 times at the 3rd place, 3 times at the 8th, 1 time at 
the 9th, 1 time 10th, 4 times came at the 13th, 3 times at the 
14th place, 2 at the 18th, 3 at the 23rd place, and 1 at the 
25

th
, 26th time, and 27th place. So, the stability in the 

ranking of experiment #3 is very weak. This experiment 
ranked in a variety of categories, with both good (3) and 
bad (27) ranks. 

• Among the 4 experiments #9, #10, #10 and #19, experiment 
#19 has the smallest GINI index value. That proves that 
experiment #19 has a higher stability rating than the other 3 
experiments. Thus experiment #19 is the best of these 4 
experiments and it is also the best of the 27 experiments 
performed. The best values of the input parameters to 
ensure minimum SR and maximum MRR at the same time 
are: 4 as the number of inserts, TiN as the insert material, 
0.8mm nose radius, 150m/min cutting speed, 30mm/min 
feed rate, and 0.5 mm depth of cut. 

• The use of different weighting methods leads to different 
ranking orders. Responding to different data normalization 
ways will result in different ranking orders for the 
alternatives. However, the simultaneous use of multiple 
weighting and multiple data normalization methods to give 
different ranking results, and then the use of the GINI index 
to choose the best solution will form the basis for 
determining which option is the best.  

VI. CONCLUSIONS 

In this study, 27 SNCM439 steel milling experiments were 
performed. At each experiment, 6 parameters were considered: 
number of inserts, cutting material, nose radius, cutting speed, 
feed rate, and depth of cut. SR and MRR were determined in 
each experiment. The PARIS method was used to rank the 
alternatives, and the stability in ranking was evaluated by the 
GINI index. Some drawn conclusions are:  

• The number of inserts, cutting speed, and feed rate have a 
great influence on surface roughness. Increasing the number 
of inserts or cutting speed reduces the surface roughness, 
while increasing the feed rate increases it. The nose radius 
and depth of cut also affect the surface roughness. Surface 
roughness is reduced if the tip radius is increased, or the 
depth of cut is decreased. On the other hand, the insert 
material does not significantly affect surface roughness. 

• The use of 3 data normalization methods is what 
distinguishes the PARIS method from other methods. For 
each data normalization method, the PARIS method also 
gives 3 ranking results for the alternatives. This is also its 
difference from the other MCDM methods. 

• The combination of the PARIS method and 3 different 
weighting methods (AW, EW, and MW) resulted in 27 
different ranking options. The combination of the PARIS 
method and the GINI index to determine the best solution 
has higher reliability instead of using just one method that 
only gives a ranking solution for the alternatives. 

• To ensure minimum SR and maximum MRR 
simultaneously, it is recommended to use the TiN insert 
with parameter values of the number of inserts, tool radius, 
cutting speed, feed rate, and depth of cut respectively as 4 
pieces, 0.8mm, 150m/min, 30mm/min, and 0.5mm. 

NOMENCLATURE 

PARIS Preference Analysis for Reference Ideal Solution 

SAW Simple Additive Weighting 

WASPAS Weighted Aggregates Sum Product ASsessment 

TOPSIS 
Technique for Order of Preference by Similarity to Ideal 

Solution 

VIKOR 
Vlsekriterijumska optimizacija i kompromisno resenje in 

Serbian 

MOORA 
Multiobjective Optimization On the basis of Ratio 

Analysis 

COPRAS COmplex Proportional ASsessment 

PIV Proximity Indexed Value 

PSI Preference Selection Index 

EDAS Evaluation based on Distance from Average Solution 

MARCOS 
Measurement Alternatives and Ranking according to 

COmpromise Solution 

CODAS COmbinative Distance based Assessment 

WASPAS Weighted Aggregated Sum Product Assessment 

WPAS Weighted Product Assessment 

MCDM Multi-Criteria Decision-Making 

MEREC Method based on the Removal Effects of Criteria 

AW Average Weight 

EW Entropy Weight 

MW Merec Weight 
 

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