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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME
599
MODELLING AND PREDICTION OF SURFACE ROUGHNESS, CUTTING
FORCE AND TEMPERATURE WHILE MACHINING NIMONIC-75 AND
NICROFER C-263 SUPER ALLOYS USING ARTIFICIAL NEURAL
NETWORK (ANN)
P. SUBHASH CHANDRA BOSE1, C S P RAO
2
1(Department of Mechanical Engineering, National Institute of Technology- Warangal, India,
[email protected]) 2(Department of Mechanical Engineering, National Institute of Technology- Warangal, India,
ABSTRACT
In the present investigation the influence of process parameters like speed, feed, depth of
cut in dry machining, are studied as surface roughness, cutting force and temperature as the
output. An artificial neural network (ANN) model was developed for the analysis and prediction
of the relationship between input and output parameters during high-speed turning of nickel-
based alloys like Nimonic-75. The input parameters of the ANN model are the cutting
parameters: speed, feed rate and depth of cut. The output parameters of the model are three,
measured during the machining trials namely surface roughness (Ra), cutting force (Fz) and
temperature (T). The model consists of a two layered feed forward back propagation neural
network. The network is trained with pairs of inputs/outputs datasets generated when machining
Nimonic-75 with TN6025 coated carbide tool. A highly efficient neural network, in agreement
with the experimental data, was achieved. The model can be used for the analysis and prediction
of the complex relationship between cutting conditions and the output parameters in metal-
cutting operations and for the optimization of the cutting process for efficient and economic
production.
Keywords: Artificial Neural Network; Nimonic-75; Surface Roughness; Cutting Force;
Temperature
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 3, Issue 3, September - December (2012), pp. 599-613
© IAEME: www.iaeme.com/ijmet.asp
Journal Impact Factor (2012): 3.8071 (Calculated by GISI)
www.jifactor.com
IJMET
© I A E M E
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME
600
1. INTRODUCTION
Machining super alloys has become an important manufacturing process, particularly in the
automotive, aerospace and gas turbine manufacturing industries.
Metal cutting is one of the important and widely used manufacturing processes in engineering
industries. The study of metal cutting focuses among others on the features of tools, input work materials,
and machine parameter settings influencing process efficiency and output quality characteristics (or
responses). The quality of a machined surface is always an important parameter in the component
performance and reliability. While machining any component, it is necessary to satisfy the surface
technological requirements in terms of high product accuracy, good surface finish and minimum of
drawbacks that may arise as a result of possible surface alterations by the machining process.
Finish hard turning is an emerging machining process which enables manufacturers to machine
hardened materials having hardness greater than 45 HRC using a single point cutting tool without any aid
of cutting fluid on a rigid lathe or turning center. This process has been developed as an alternative to the
grinding process in a bid to reduce the number of setup changes, product cost and lead time without
compromising on surface quality to maintain competitiveness. For successful implementation of hard
turning, selection of suitable cutting parameters for a given cutting tool work piece material and machine
tool are important and need to be developed through experimentation as the suitable cutting parameter
are not available.
Machining of super-alloys is a challenging task. Nickel based super-alloys like Nimonic, Nicrofer
and Niobium have got wide application in missile technology and other defense applications due to its
strength at high temperatures. Hence evaluation of machining parameters is the need of the hour for
manufacturing of super-alloy components.
Hence an attempt is made by the author to evaluate surface finish, cutting force and temperature in
machining of Nimonic-75 and Nicrofer C-263 alloys. Several experiments were conducted using DOE
and ANOVA analysis was done on the output parameters. The process is simulated by modeling with
ANN for prediction of surface finish, cutting force and temperature at different values of speed, feed and
depth of cut.
An artificial neural network (ANN), usually called neural network (NN), is a mathematical model
or computational model that is inspired by the structure and/or functional aspects of biological neural
networks. A neural network consists of an interconnected group of artificial neurons and it processes
information using a connectionist approach to computation. In most cases an ANN is an adaptive system
that changes its structure based on external or internal information that flows through the network during
the learning phase. Modern neural networks are non-linear statistical data modeling tools. They are
usually used to model complex relationships between inputs and outputs or to find patterns in data.
Fig 1 Dimensions of the Carbide Tool
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME
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2. MODEL DESCRIPTION
There has been in an increase in the research interest in the applications of ANN’s modeling the
relationship between the cutting conditions and the process parameters during the machining process.
The input parameters of the neural networks being the speed, feed and depth of cut and the output
parameters are three of the most important process parameters namely, surface roughness (Ra), Cutting
forces (Fz) and Cutting Temperature (T).
The five basic steps used in general application of the neural networks are adopted in the development
of the model: assembly or collection of data; analysis and pre-processing of the data; design of the
network object; training and testing of the network; and performing simulation with trained network and
post –processing of results.
2.1 Experimentation/collection of input/output data set
Rigid, high power, 12kW VDF retrofitted CNC lathe with a speed of 56-3550 rpm. 38 mm
diameter and 250 mm long cast solution treated, annealed and hardened, nickel chromium alloy with
controlled additions of titanium and carbon, Nimonic 75, alloy bars were used. The chemical
composition and physical properties of the work pieces are given in Table 1 and 2, respectively. Before
conducting the machining trails, up to 2 mm thickness of the top surface of each bar was cleaned in order
to eliminate any skin defect that can adversely affect the machining results.
Multi-layered PVD coated cemented tungsten carbide inserts were used for the turning tests. The
coated carbide grade was TN6025; the dimensioning of the tool is given in fig 1, which is designed for
light and medium turning operations of high temperature alloys. TN6025 inserts are Nano-multilayered
TiAlN coated insert, having very high wear resistance and also good toughness.
Table 1
Chemical composition of Nimonic 75 (wt %)
Element C Cr Cu Fe Mn Si Ti Ni
Wt (%) 0.08 18 0.5 5 1.0 1.0 0.2 Balance*
Table 2
Physical Properties of Nimonic 75
Hardness
(HRC)
Density
(mg/m3)
Melting Point
(0C)
Thermal conductivity
(W/mK)
Electrical Resistivity
(µΩ.m)
28 8.37 1340 11.7 1.09
The measurements of average surface roughness (Ra) were made on HANDYSURF E 35 B. Three
measurements of surface roughness were taken at different locations and the average value is used in the
analysis. It directly gives the value in digital format.
Infrared thermometer Kiray 300 was used for temperature measurement, while conducting the
experiments. This is a thermometer used to diagnose, inspect and check any temperature. Thanks to its
elaborated optical system with a dual laser sighting, it allows easy and accurate measurements of little
distant targets. The KIRAY 300 instrument has an internal memory which can save up to 100
measurements. Compatible with thermocouple K probe.
Four-component dynamometer was used to measure the cutting force components. This
dynamometer can be used for measuring a torque Mz and the three orthogonal components of a force.
The dynamometer has a great rigidity and consequently a high natural frequency. Its high
resolution enables the smallest dynamic changes in large forces and torques to be measured.
Compact and robust multi-component force measuring instrument
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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2.2 Preprocessing of input/output datasets
The working ranges of the parameters, for the subsequent design of experiment, were selected
based on tool manufacturer recommendations and machine tool capabilities. In the present experimental
study, three parameters such as speed, feed and depth of cut have been considered as process variables
with 5, 4, 3 levels respectively. The levels have been so selected based on the intuition of the affect of
these parameters on the output process parameters. The values are listed in Table 3 below.
TABLE 3 Cutting Level
Controllable factors Level 1 Level 2 Level 3 Level 4 Level 5
Speed 30 36.25 42.5 48.75 55
Feed 0.08 0.12 0.16 0.20 -
Depth of cut 0.5 1.0 1.5 - -
Experiments have been carried out using full factorial experimental design which consists of 60
combinations of speed, feed and depth of cut. Out of which 50 have been used for training the neural
networks and 10 have been used for testing the networks. The design of experiment has been shown in
Table 4.
TABLE 4 Designs of Experiments S. No Speed Feed Doc
1 42.5 0.12 1.5
2 42.5 0.12 0.5
3 55 0.12 1
4 30 0.12 1
5 42.5 0.16 1
6 55 0.08 1
7 48.75 0.2 0.5
8 36.25 0.16 1
9 48.75 0.12 1
10 36.25 0.08 1
11 36.25 0.2 1.5
12 36.25 0.12 1.5
13 30 0.2 0.5
14 48.75 0.16 1
15 36.25 0.12 1
16 30 0.08 1.5
17 36.25 0.2 0.5
18 48.75 0.08 1.5
19 55 0.16 1
20 30 0.08 1
21 55 0.12 0.5
22 48.75 0.08 1
23 30 0.08 0.5
24 48.75 0.08 0.5
25 42.5 0.2 0.5
26 48.75 0.2 1.5
27 30 0.16 1.5
28 42.5 0.2 1.5
29 36.25 0.08 0.5
30 42.5 0.08 1.5
31 42.5 0.08 1
32 55 0.08 0.5
33 36.25 0.16 1.5
34 30 0.16 1
35 55 0.08 1.5
36 30 0.2 1.5
37 55 0.2 1
38 55 0.16 1.5
39 42.5 0.08 0.5
40 48.75 0.2 1
41 36.25 0.2 1
42 48.75 0.12 0.5
43 36.25 0.08 1.5
44 48.75 0.16 1.5
45 36.25 0.12 0.5
46 30 0.12 0.5
47 30 0.16 0.5
48 42.5 0.16 1.5
49 55 0.2 0.5
50 55 0.12 1.5
51 55 0.16 0.5
52 42.5 0.2 1
53 30 0.12 1.5
54 55 0.2 1.5
55 36.25 0.16 0.5
56 48.75 0.12 1.5
57 30 0.2 1
58 42.5 0.12 1
59 48.75 0.16 0.5
60 42.5 0.16 0.5
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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2.3 Neural network design and training
The network architecture or feature such as number of neurons and layers are very important
factors that determine the functionality and generalization capability of the network. For this model,
standard multilayered feed-forward back propagation hierarchical neural networks were designed with
MATLAB 7.7 Neural network toolbox. The network consists of 4 layers, one input, two hidden layers
and one output layer. In general, the networks have three neurons in the input, corresponding to each of
the three cutting parameters and one neuron in the output, corresponding to each of the process
parameter. For all networks, linear transfer function ‘purelin’ has been used for input and output layers
and tangent transfer sigmoid transfer function ‘tansig’ were used in the hidden layers. Three different
neural network models are used, one for the prediction of surface roughness, second for the prediction of
cutting force and third for the prediction of temperature.
The networks were trained with Levenberg-Marquardt algorithm. This training algorithm was
chosen due to its high accuracy in similar function approximation [3, 15]. In order to improve the
generalization of the network, a ‘regularization’ scheme was used in conjunction with the Levenberg-
Marquardt algorithm. The automatic Bayesian regularization was used.
For training with Levenberg-Marquardt combined with Bayesian regularization, the input/output
dataset was divided randomly into two categories: training dataset, consisting of 50 of the input/output
dataset and the remaining as the test dataset.
2.4 Testing and performance of the network
In order to determine the optimum number of neurons in the hidden layers, the testing was done
taking 5, 10, 15, 20, 25 neurons in each hidden layer and for each iteration the best performance error
was calculated and then compared. Table 5 shows the combinations of neurons in the first and second
hidden layers and the best performance error calculated for all the iterations for the surface roughness
process parameter. The values of the error with 20 neurons in the second hidden layer are lower than the
other error values for all the other combinations. Table 6 gives us the values of best performance error
for surface roughness parameter by iterating the neurons in the 1st hidden layer with fixed neurons in the
second hidden layer. Table 7 and 8 show us the iterations through which the final set of neurons have
been selected. Thus, the network having two layers of 20 neurons and 19 neurons, respectively, trained
with Levenberg-Marquardt algorithm and Bayesian regularization has been chosen as the optimum
network and used for development of this model. The performance of the model for prediction of the
surface roughness with an error of 0.00262 has been developed. The combination which gave the least
Fig 2 Picture Depicting the Layers in a Neural
Network
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error was selected for the testing of the neural networks. The predicted values from the neural network
are then compared to the experimentally obtained values. Three inputs are taken for all the three
networks, which are speed, feed and depth of cut. In this, linear function was used for input layer/ output
layer and sigmoid function is used for hidden layers. This demonstrated that the models have high
accuracy for predicting the process parameters. Acceptable results have were also obtained for all the
process parameters. The analysis of variance (ANOVA) was performed to statistically analyze the
results. An ANOVA summary table is commonly used to summarize the test of the regression
model, test of the significance factors and their interaction and lack-of-fit test. If the value of
‘Probability > F’ in ANOVA table is less than 0.05 then the model, the factors, interaction of
factors and curvature are said to be significant. Finally, % contribution column is added in ANOVA
summary table and it often serves as a rough but an effective indicator of the relative importance of each
model term.
TABLE 5 Best Performance Error for Surface Roughness parameter by iterating the neurons in the
second hidden layer
No of Neurons
in 1st Hidden
Layer
No of Neurons
in 1st Hidden
Layer
Best Performance
Error
5 5 0.0242
5 10 0.379
5 15 0.0386
5 20 0.0142
5 25 0.0268
10 5 0.0468
10 10 0.0486
10 15 0.0562
10 20 0.013
10 25 0.142
15 5 0.0565
15 10 0.0642
15 15 0.0541
15 20 0.0124
15 25 0.0329
20 5 0.0142
20 10 0.0263
20 15 0.0281
20 20 0.00834
20 25 0.0142
25 5 0.0163
25 10 0.024
25 15 0.029
25 20 0.0381
25 25 0.024
TABLE 6 Best Performance Error for Surface Roughness parameter by iterating the neurons in the first
hidden layer with fixed neurons in the second hidden layerNo of Neurons in 1
st
Hidden Layer
No of Neurons in 1st Hidden
Layer Best Performance Error
5 20 0.0142
10 20 0.013
15 20 0.0124
20 20 0.00834
25 20 0.0381
TABLE 7 Best Performance Error for Surface Roughness parameter, to fix the neurons in the first hidden layer
No of Neurons in 1st
Hidden Layer
No of Neurons in 1st Hidden
Layer Best Performance Error
15 20 0.0124
17 20 0.0139
19 20 0.0432
20 20 0.00834
21 20 0.0328
23 20 0.056
25 20 0.0381
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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TABLE 8 Best Performance Error for Surface Roughness parameter, to fix the neurons in the
second hidden layer
No of Neurons in 1st
Hidden Layer
No of Neurons in 1st
Hidden Layer
Best Performance
Error
20 15 0.0281
20 17 0.0174
20 18 0.0382
20 19 0.0262
20 20 0.0834
20 21 0.0943
20 23 0.0262
20 25 0.0142
3. Results and Discussions
3.1 Results
The predicted values and experimental values of surface roughness, cutting force and
temperature both training and testing are shown in the fig 3, 4 and 5, respectively. From the
above said figures it is evident that network responded well for the testing data as well.
Fig. 3 Experimental and predicted Ra values
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME
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Fig. 4 Experimental and predicted Cutting Force values
Fig. 5 Experimental and predicted Temperature values
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Table 9 Ra values
Table 10 Cutting Force values
Exp no Measured
values
Predicted
values
Percentage
of error
1. 1.31 1.25 4.58
2. 1.71 1.65 3.50
3. 0.82 0.75 8.53
4. 0.97 0.90 7.21
5. 0.72 0.62 13.88
6. 0.8433 0.733 13.07
7. 1.15 1.02 11.30
8. 2.18 2.08 4.58
9. 1.36 1.25 8.08
10. 0.97 0.80 17.52
Exp
no
Measured
values
Predicted
values
Percentage
of error
1. 407.3 423.715 4.1301
2. 555.9 549.0548 1.231
3. 119.3 107.41 9.96
4. 88.72 79.72 10.14
5. 164.2 150.24 8.501
6. 617 610.55 1.134
7. 477.7 487.7 2.093
8. 275.3 276.0625 0.276
9. 375.2 377.8248 0.699
10. 184.5 175.15 5.067
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Table 11 Temperature values
Exp
no
Measured
values
Predicted
values
Percentage
of error
1. 154.5 152.1884 1.49
2. 148.5 145.9225 1.73
3. 70.4 74.708 6.11
4. 73.1 70.2374 3.91
5. 168.3 160.45 4.66
6. 170.2 165.02 4.01
7. 96.6 89.6 7.24
8. 92.2 80.6 12.58
9. 137.7 125.922 8.55
10. 82.8 75.7979 8.45
3.2 Evaluation of performance of the network
From different runs of the program, the best architectures are found to be that training 10
neurons in the hidden layer and regression R=0.8661 and no of epochs=69for the prediction of
Ra. 20 in the hidden layer and the R=0.9065 and no of epochs=93 for the prediction of
temperature, 44 neurons in the hidden layer and the R=0.90581 and no of epochs=89for the
prediction of cutting forces.
Mean relative error is used for evaluation of performance of the networks. The calculated
mean relative errors of the network used for predicting surface roughness, temperature and
cutting forces found to be 0.92% ,5.873% and4.32% respectively. These values show that the
accuracy of neural network is good.
3.3 Response tables for surface roughness, cutting force and temperature without interactions.
Table 12 Response table for Ra
Level Speed Feed Doc
1 1.3283 0.973 1.0905
2 1.0192 1.1693 1.3640
3 1.1342 1.2707 1.2202
4 1.1775 1.4860 -----
5 1.4653 ----- -----
Max-Min 0.4461 0.513 0.2735
Rank 2 1 3
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Table 13 Response table for Cutting Force
Level Speed Feed Doc
1 106.10 114.13 87.89
2 114.45 115.51 116.86
3 111.15 108.67 127.73
4 103.68 105.00 -----
5 118.76 ----- -----
Max-Min 15.08 10.51 39.84
Rank 2 1 3
Table 14 Response table for Temperature
Level Speed Feed Doc
1 285.6 235.6 155.0
2 327.9 285.8 305.6
3 318.9 346.8 467.1
4 309.6 368.7 -----
5 304.1 ----- -----
Max-Min 42.3 133.1 312.1
Rank 2 1 3
3.4 Analysis of variance tables for surface roughness, cutting force and temperature
Table 15 ANOVA table for Ra
S. No Source DOF Sum of squares Mean squares F Value % contribution
1 Speed 4 1.4554 0.3639 1.51 8.91
2 Feed 3 12.0480 0.6827 2.88 73.82
3 Doc 2 0.7487 0.3743 0.59 4.58
4 Error 50 1.6652 0.2413 ----- -----
5 total 59 16.3192 ----- ----- -----
Table 16 ANOVA table for Cutting Force
S. No Source DOF Sum Of Squares Mean Squares F Value % Contribution
1 Speed 4 12319 3080 0.55 8.6
2 Feed 3 163632 54544 9.72 11.4
3 Doc 2 974660 487330 86.87 68.10
4 Error 50 280507 5610 ----- -----
5 Total 59 1431118 ----- ----- -----
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Table 17 ANOVA table for Temperature
S.No Source DOF Sum Of Squares Mean Squares F Value % Contribution
1 Speed 4 16966.5 448.9 0.96 39.16
2 Feed 3 1070.7 356.9 0.76 2.47
3 Doc 2 23483.9 8483.2 18.06 54.21
4 Error 50 1795.6 469.7 ----- -----
5 Total 59 43316.7 ----- ----- -----
From the analysis of table 15, we can observe that the cutting factors speed (p= 8.91%), feed
(p= 73.82%), doc (4.58%) have statistical significance on the surface roughness obtained,
especially the feed. From the analysis of the table 16, we can observe that the cutting factors speed
(P=8.6%), feed (P=11.9%) and Doc (P=68.01%) have statistical significance on the cutting force
obtained, especially the Doc. From the analysis of the table 17, we can observe that the cutting factors
speed (P=.21%), feed (P=2.47%) and Doc (P=39.1654%) have statistical significance on the
temperature obtained, especially the Doc.
3.5 Analysis of variance tables for surface roughness, cutting force and temperature with
interactions.
Table 18 ANOVA table for Ra with interactions
S.No Source DOF Sum of squares Mean square F Value % contribution
1 Speed 4 1.4554 0.3639 1.63 8.91
2 Feed 3 5.3677 0.6827 3.05 32.10
3 Doc 2 0.7487 0.3743 1.67 4.5
4 Speed*feed 12 2.8356 0.2363 1.06 17.37
5 Speed*doc 8 1.2415 0.1552 0.69 7.60
6 Feed*doc 6 2.6223 0.4370 1.95 16.06
7 Error 24 2.0480 0.2337 ----- -----
8 Total 59 16.3192 ------ ----- -----
Table 19 ANOVA table for Cutting Force with interactions
S.No Source Dof Sum of squares Mean square F Value % contribution
1 Speed 4 12319 3080 0.68 0.8
2 Feed 3 163632 54544 12.06 11.43
3 Doc 2 974660 487330 107.73 68.10
4 Speed*feed 12 55041 4587 1.01 3.84
5 Speed*doc 8 74288 9286 2.05 5.19
6 Feed*doc 6 42613 7102 1.57 2.97
7 Error 24 108565 4524 ----- -----
8 total 59 1431118 ----- ----- -----
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Table 20 ANOVA table for Temperature with interactions
S.No Source Dof Sum of squares Mean square F Value % contribution
1 Speed 4 14323.5 448.9 0.75 33.06
2 Feed 3 1070.7 356.9 0.60 2.47
3 Doc 2 16966.5 8483.2 14.21 39.16
4 Speed*feed 12 3256.6 271.4 0.45 7.518
5 Speed*doc 8 3990.1 498.0 0.84 4.416
6 Feed*doc 6 1913.1 319.0 0.53 4.419
7 Error 24 1797.6 596.0 ----- -----
8 total 59 43316.7 ----- ----- -----
From the analysis of table 18, we can observe that the cutting factors speed (P=8.91%),
feed (P=32.10%), doc (P=4.5%), speed*feed (P=17.37%), speed*doc (P=7.6%), feed*doc
(P=16.06%) have statistical significance on the surface roughness obtained, especially the feed.
From the analysis of table 19, we can observe that the cutting factors speed (P=8.6%), feed
(P=11.43%), doc (P=68.10%), speed*feed (P=3.84%), speed*doc (P=5.19%), feed*doc
(P=2.97%) have statistical significance on the cutting force Fz obtained, especially the doc. From
the analysis of table 20, we can observe that the cutting factors speed (P=39.16%), feed
(P=2.47%), doc (P=33.06%), speed*feed (P=7.518%), speed*doc (P=4.416%), feed*doc
(P=4.419%) have statistical significance on the temperature obtained, especially the speed and
doc.
As we increase the speed, the input parameter, from figure 6, the Surface roughness
initially decreases and later on increases more or less reaching to the same initial value of surface
roughness within the range of input parameters taken. With increase in feed, from figure 7, the
surface roughness does on increasing. Whereas with increase in depth of cut, the surface
roughness has no significant effect, figure 8.
For the cutting forces as the output parameter, from figure 9, as we increase the speed, the
cutting forces initially increase forming a peak and later on decrease. With increase in the feed,
from figure 10, the cutting forces increase rapidly. Similarly with increase in depth of cut the
cutting forces are increasing, from figure 11.
With increase in speed, the Temperature have seen a initial increase in temperatures with a
local minimum and then a increasing trend as we increase the speed, from figure 12. From figure
13, with increase in feed the temperature first increased and later on decreased. With increase in
depth of cut, the temperature goes on increasing, from figure 14.
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Fig. 6 Speed Vs ‘Ra’ mean Fig.7 Feed Vs ‘Ra’ mean
Fig. 8 D.O.C Vs ‘Ra’ mean Fig.9 Speed Vs ‘Fz’ mean
Fig. 10 Feed Vs ‘Fz’ mean
Fig.11 D.O.C Vs ‘Fz’ mean
Fig. 12 Speed Vs Temperature mean Fig.13 Feed Vs Temperature mean
Fig. 14 D.O.C vs. Temperature mean
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4. CONCLUSIONS
1. The plot of experimental and predicted values from neural network shows that the network has
been trained well and has good generalization ability.
2. The network having two layers of 20 neurons and 19 neurons, respectively, trained with
Levenberg-Marquardt algorithm and Bayesian regularization has been chosen as the optimum
network and used for development of this model.
3. The performance of the model for prediction of the surface roughness with an error of 0.00262
has been developed.
4. The optimum cutting speeds at which the minimum process parameters were obtained were is
35, 55 and 48.75 for surface roughness, cutting forces and temperature respectively.
5. With increase in feed, the output parameters surface roughness and cutting forces have
increased consistently, while temperatures have decreased.
6. Depth of cut has had the same effect, more or less, on all the parameters. With increase in the
depth of cut all the output parameters have increased.
REFERENCES
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