23.12.2014 Views

OCTOBER 19-20, 2012 - YMCA University of Science & Technology

OCTOBER 19-20, 2012 - YMCA University of Science & Technology

OCTOBER 19-20, 2012 - YMCA University of Science & Technology

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

( ∏d i<br />

) n<br />

The d i<br />

Proceedings <strong>of</strong> the National Conference on<br />

Trends and Advances in Mechanical Engineering,<br />

<strong>YMCA</strong> <strong>University</strong> <strong>of</strong> <strong>Science</strong> & <strong>Technology</strong>, Faridabad, Haryana, Oct <strong>19</strong>-<strong>20</strong>, <strong>20</strong>12<br />

for "in range" are included in the product <strong>of</strong> the desirability function "D", but are not counted in<br />

determining "n": D = .<br />

If the goal is none, the response will not be used for optimization.<br />

Table 4 Range <strong>of</strong> Input Parameters and MS for Desirability<br />

Constraint<br />

Name<br />

Goal<br />

Lower<br />

Limit<br />

Upper<br />

Limit<br />

Lower<br />

Weight<br />

Upper<br />

Weight Importance<br />

Pulse-on Time(Ton) is in range 108 122 1 1 3<br />

Pulse-<strong>of</strong>f Time(T<strong>of</strong>f) is in range 30 50 1 1 3<br />

Servo Voltage (SV) is in range <strong>20</strong> 40 1 1 3<br />

Wire feed rate (WF) is in range 4 8 1 1 3<br />

Machining Speed Maximize 5.12 32.58 1 1 3<br />

0.989<br />

1.000<br />

0.800<br />

Desirability<br />

0.600<br />

0.400<br />

0.<strong>20</strong>0<br />

0.000<br />

50.00<br />

45.00<br />

B: T<strong>of</strong>f<br />

40.00<br />

35.00<br />

30.00<br />

122.00<br />

1<strong>20</strong>.00<br />

118.00<br />

116.00<br />

114.00<br />

112.00<br />

A:Ton<br />

110.00<br />

108.00<br />

Figure 3 Desirability plot for maximum MS<br />

[Max. Desiarbility (0.9887) occurs at Ton 122, T<strong>of</strong>f 30, SV: <strong>20</strong>; WF: 8]<br />

4.1 Optimal Solution<br />

The goal <strong>of</strong> optimization is to find a good set <strong>of</strong> conditions that will meet the desired goal. It is not necessary that<br />

the value <strong>of</strong> desirability is always 1.0 as the value is completely dependent on how closely the lower and upper<br />

limits are set relative to the actual optimum value (Aggarwal et. al., <strong>20</strong>08). The set <strong>of</strong> conditions possessing<br />

highest desirability value have been selected as optimum conditions for maximum MS. The constraints for the<br />

optimization <strong>of</strong> MS have been listed in Tables 4. Using Design expert (DX-8), optimal solutions have been<br />

derived for specified design space constraints for machining speed. Table 5 shows the set <strong>of</strong> conditions<br />

correspond to maximum desirability value for MS. Figure 3 shows the 3D surface plot for desirability.<br />

Sr.<br />

No.<br />

Table 5 Optimal conditions for maximizing MS<br />

A B C D Desirability Predicted<br />

(Ton) (T<strong>of</strong>f) (SV) (WF) value Value<br />

1 122 30 <strong>20</strong> 8 0.9887 32.271 32.58<br />

Confirmatory<br />

value<br />

5. Conclusion<br />

In this paper, four important WEDM parameters namely pulse-on time, pulse-<strong>of</strong>f time, servo voltage and wire<br />

feed rate have been investigated and modelled for machining speed <strong>of</strong> WC-5.3%Co composite during rough<br />

cutting operation on WEDM. Using response surface methodology, face centered central composite design has<br />

been adopted to perform the experiments. Quadratic Vs two factors interaction (2FI) has been found the best fit<br />

model for machining speed. Using desirability function, parameters have been predicted for maximizing the<br />

machining speed. Confirmatory results show the adequacy <strong>of</strong> the predicted model.<br />

447

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!