Affiliation(s)
1. Department of Mechanical Engineering Technology, Federal Polytechnic, Ado-Ekiti 360231, Ekiti State, Nigeria
2. Mechatronics Engineering Department, Federal University, Oye-Ekiti 374101, Ekiti State, Nigeria
3. Industrial and Production Engineering Department, Federal University of Technology, Akure 340001, Ondo State, Nigeria
ABSTRACT
Mild steel plates of
thicknesses 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm and 1.0 mm were prepared as
test samples. After welding with the developed welding robot and manual
electric arc welding machine these test samples were subjected to Tensile
Strength and Hardness tests. All data obtained including hardness, load and
extension were analyzed and the data produced from electric arc welding
operations, the robot welding operations and un-welded plates (control) were
compared with one another. The statistical analyses of hardness, load and extension tests for
developed welding robot, manual electric arc welding and un-welded (control)
mild steel plates of different thicknesses were carried out. The results
revealed that for hardness, the developed robot welding has the highest mean
value of 115.30, standard deviation value of 14.32 and variance value of
205.06. The descriptive statistics of the load showed that the developed robot
welding samples collectively have the lowest mean value of 2,536.85, standard
deviation value of 704.21 and variance value of 495,911.72. The descriptive statistics of the extension in which the
developed robot welding samples collectively have the lowest mean value of
1.29, standard deviation value of 0.43 and variance value of 0.18 were also
determined. The result for hardness showed homogeneity of variance among
hardness tests of the samples, which implies
variation in the hardness test among the tests of the samples since p-value is 0.038. While the result for
loads shows homogeneity of variance among loads of the samples in which the
result reveals that there is no variation in the loads among the tests of the
samples since p-value is 0.322. The
result for extension shows homogeneity of variance among extensions of the
samples in which it revealed that there is variation in the extensions among
the tests of the samples since p-value
is 0.011. The analysis of
variance (ANOVA) test result revealed
that there is a significant
difference in the hardness of the samples in which developed robot welding
operation gave the highest hardness
compared with electric arc welding and un-welded (CONTROL) since p-value is 0.028. The ANOVA test result
for load revealed that there is no significant difference in the loads of the
samples since p-value is 0.51. The
ANOVA test result of the extension shows that there is a significant difference in the extension of the samples in which
developed robot welding operation gave the lowest extension compared with
electric arc welding and un-welded (CONTROL) since p-value is 0.001. The results of hardness also showed the mean
difference of 16.48 between developed robot welding and un-welded (CONTROL)
samples and 7.26 between developed robot welding and electric arc welding
samples. Finally, for extension the mean difference of -5.28 between developed
robot welding and un-welded (CONTROL) samples and -1.22 between developed robot
welding and electric arc welding samples were established.
KEYWORDS
Statistical analysis, welding processes, load, extension, hardness, mild
steel.
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