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

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
Substituting the values of various terms in the above equation
μ HR = 107.04 + 103.58 + 104.88 + 103.10 + 106.47 + 107.96- 5× 108.48 = 90.73
The 95% confidence interval of confirmation experiments (CICE) and of population (CI POP ) is calculated by
using the following equations:
Where Fα (1,fe): The F ratio at the confidence level of (1-α) against DOF 53 and error DOF fe=42, N: Total
number of results = 54 (Treatment=18, Repetition=3), R : Sample size for confirmation experiments =3Ve: Error
variance = 1.06, fe error DOF = 42.
N efficiency = N/1+ [DOF associate in the estimate of mean response] = 4.5
F0.05 (1, 42) = 4.076 (tabulated F value), So CI CE = ±5.87, CI POP = ±3.71
The predicted optimal range (for a confirmation runs of three experiments) is :
μ HR – CI CE < μ HR < μ HR + CI CE ; 84.86< μ HR < 96.6
The 95% conformation interval of the predicted mean is as follows:
μ HR – CI POP < μ HR < μ HR + CI POP ; 87.02 < μ HR < 94.44
The optimal value of process parameters for the predicted range of optimal HR are as follows: Type of Handle
position (A, 1st level) = upper handle, Box size (B, 1st level) = 25*25*25, Worker (C, 1st level) = 1, vertical
distance (D, 1st level) = Knee, weight (E, 1st level) = 10kg, Horizontal position (F, 1st level) = 20cm.
4.1.2. Confirmation Experiment for HR:
The purpose of confirmation experiment is to validate the conclusions drawn during the analysis phase. The
three confirmation experiments for HR are conducted at the optimum setting of the process parameters. The type
of handle is set at 1st level, box size at 1st level, worker at 1st level, handling position at 1st level, weight at 1st
level, horizontal distance at 1st level. The Confirmation experimental value of average HR is found to be
92.7/min, which fall within the 95% confidence interval of the predicted optimum parameters.
5. Conclusion:
In this study we found that handle plays an important role in manual material handling tasks. If the better
position of the handle could be found then we can minimise the work related injuries. It was concluded from
figure 2 that the value of HR was less in case of upper handle position as compare to lower handle position, so
upper handle position was found more suitable to worker for lifting in present study . This happened because in
case of lower handle position worker has to bend more to pick the box as compared to lower handle box position
which resulted in increased HR of worker. Other facts found in experiment are given below.
• The optimum levels of parameters for HR are: handle position (level 1), 25 box size (level 1), first worker
(level 1), knee position vertical distance (level 1), 10kg weight (level 1) and 20cm horizontal distance (level 1).
• For HR, the maximum percentage contributions of four factors are worker (27.55%), vertical distance
(19.31%), box size (17.55%) and weight (11.00%) respectively.
• The predicted optimal range for HR was CI POP : 84.86