Figure 4.9: the surface roughness can be obtained from the combination of parameter in no 1
The figure 4.9 shows the combination of each parameter range to produce the optimum surface roughness. The parameter range is set based on the chosen experimental range.
The combination of cutting speed Vc 150 mmin, feed rate fz 0.1mmmin and width of cut ae 8mm will produce the approximate surface roughness, Ra value of 0.186 µm.
4.9 Validation of optimization model
The validation process is performing to obtain the error between the mathematical model and experimental result. It is done by comparing the surface roughness obtained
from the model with surface roughness obtained from the experiment that used the random and optimized parameter. Surface roughness obtained from the experiment by
using optimized parameter is 0.1725 µm with the error of 8. While, the surface roughness obtained from the experiment by using random optimized parameter is
0.3185 µm with the error of 9. The obsolete errors found during the experiment are caused by chip formation and the vibration error. The chip formed during machining
is stick to the tool inserted and it disturbs the machined surface area. The vibration that comes from nearby machine is causing the result to be unreliable thus producing a
bigger error during validation process.
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Figure 4.10: The surface roughness of optimized parameter with error 8.
Figure 4.11: The surface roughness of random parameter with error 9
From the figure 4.10, the validation of the model and optimized parameter shows the optimum value from the model is 0.186 µm with the error of 8. The average from
the experimental result is 0.173 µm. Moreover, based on figure 4.11, the surface
surface roughness, µm
number of reading OPTIMIZED
optimization model
surface roughness, µm
number of reading RANDOM
random model
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roughness value that was obtained from using random parameter is 0.346 µm with the error of 9. The average obtained when using experimental value is 0.3185 µm.
Table 4.6: Comparisons between surface roughness model and experimental result
OPTIMIZED RANDOM
Average experiment 0.1725
0.3185 standard deviation
0.02531382 0.042460508
maximum 0.23
0.43 max
33 35
minimum 0.14
0.27 min
23 18
Ra optimization 0.186173
0.346182 error
8 9
Table 4.6 shows the validation between surface roughness obtain from experiment result and surface roughness calculated by using mathematical model is done to verify
the result from mathematical model is closed to experimental data with an error below than 10 . The optimized parameter calculated is 0.186 µm compared to experimental
result of 0.173 µm with an error of 8 is can be consider as small. For random parameter, the actual surface roughness from the model is 0.346 µm compared to the
experiment that is 0.319 µm with an error of 9. As a conclusion, both of two set parameters show a low error that is below 10. This error is acceptable according to
Hills and Trucano, 1999.
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CHAPTER 5
CONCLUSION
The conclusion made are based on the experimental objective that have been done in study of the effect of cutting parameter in milling operation by using AISI D2 tool
steel with use of end mill tool insert and the machining is performed under flooded condition:
1. The factor used, cutting speed Vc is the most significant toward surface roughness followed by feed rate fz and lastly the width of cut ae. From the
result in this experiment, high cutting speed can produce the best surface roughness. In addition the feed rate also significant to influence the surface
roughness by reducing the feed rate to its minimum. The width of cut does not influence significantly compared to others parameters but, it tends to
reduce the surface roughness when width of cut is increasing.
2. The mathematical model is build based on the data collected. The linear model is constructed for simulated the result of the surface roughness to the
expected result.
Surface roughness model, see equation 5.1 Ȓa = 0.758328 – 0.0045 x Vc + 1.600156 x fz
– 0.00706 x ae ± e Equation 5.1
3. The optimization is performing based on the two set of the cutting parameters that consists of optimized parameter and the random parameter.
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Set of the optimized parameter includes cutting speed of 150 mmin, feed rate of 0.1 mmmin and the width of cut of 8mm. the surface roughness
calculated by using mathematical model is 0.186 µm. the error obtain by comparing between the model and the experimental result is about 8. The
error value is still acceptable because it can be considered small. The ranges of random parameters used are cutting speed 150mmin, feed
rate 0.20 mmtooth, and width of cut 8mm. The surface roughness calculated by using the mathematical model is 0.346µm. the average
surface roughness calculated from the experiment is 0.319 µm and the error between model and experiment is 9 which is acceptable due to its lower
than 10.
5.1 SUGGESTION AND RECOMMENDATION FOR FUTURE STUDY
