Question

Comparison of ANOVA with Taguchi Approach: as a report
Solving the same problem with ANOVA and Taguchi

Answer 1

The Taguchi method involves reducing the variation in a process through robust
design of experiments. The overall objective of the method is to produce high quality
product at low cost to the manufacturer. The Taguchi method was developed by Dr. Genichi Taguchi, a method for designing experiments to investigate how different
parameters affect the mean and variance of process performance characteristics that defines how well the process is functioning. The Taguchi method gives the S/N ratio asthe performance index to evaluate the characteristics of the product or process. It can beeasily defined as the ratio of the mean (signal) to the standard deviation (noise) by S/N ratio. The S/N ratios may be depended on the particular type of performance
characteristics, including smaller-is-better (ZS) or larger-is-better (ZL).

Analysis of variance (ANOVA) is one of the statistical models used to study the
difference among group means plus their connected procedures like differences between groups. In ANOVA, the variance observed in a prescribed parameter is divided into parts attributable to various sources of deviation. ANOVA provides a statistical test of means
for several groups are equal or not and accordingly generalizes the t-test for more than two groups. By many t-tests of two-samples will increase chance of a type I error.
Because of which, ANOVAs are useful in comparing three or more means for statistical significance.

In this study, Orthogonal array L9(3
3
) [50] experimental design method was
chosen to determine the experimental plan. In this study the control parameters like
porosity, heat input, and thermal conductivity of material were set as a level as shown in
Table 9.5. In order to observe the effect of noise to source ratio on the heat transfer
coefficient each experiment was repeated three times under the same condition as per
L9(3
3
) table. Values were determined by comparing the standard method and analysis of
variance (ANOVA) which is based on the Taguchi method. The objective was to obtain
performance characteristics (maximum heat transfer coefficient) hence, larger the better
was chosen.

As explained above the parameters chosen are: Heat input, Porosity and Fin
material and the heat transfer coefficient was the measure of the outcomes of varying
these parameters. In this study, from experimental readings, the average heat transfer coefficient
(ha) was used to calculate the S/N ratio.

Both the values of ha and S/N ratio, are presented in aboveTable. After calculating
the S/N ratio for each experiment, the average S/N value is calculated for each factor and
level. For example, the mean S/N ratio for the heat input level II can be calculated by
averaging the S/N ratios for experiment no. 1, 4, 7, and for level II experiment no. 2, 5, 8
and for level III experiment no 3, 6, 9. The mean S/N ratio for each level of the other
parameters can be computed in similar manners that are presented in the response Table(below). The main effect of each parameter is nothing but difference of highest and lowest value among the levels.

Last table indicates that porosity ratio having 50.23 % contribution and more
significant, material (thermal conductivity) having 29.38% contribution and heat input
having 20.39%contribution and less significant influence upon the maximum heat
transfer coefficient in our study.