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
STUDY OF MANUAL MATERIAL HANDLING TASKS USING
TAGUCHI TECHNIQUE
Jaswinder Singh 1 , P Kalra 2 , R S Walia 3
1
Research Scholar, Department of Production Engineering, PEC University of Technology, Chandigarh, UT
2 Professor, Department of Production Engineering, PEC University of Technology, Chandigarh, UT
2
Associate Professor, Department of Production Engineering, PEC University of Technology, Chandigarh, UT
e-mail:: waliaravinder@yahoo.com
Abstract
Measurement of energy expenditure of the worker during manual material handling (MMH) task depends upon
various parameters that can be used to assign the task to particular worker. In this study three important
variables related to MMH task i.e. Worker’s Age, Work Time Duration and Work Place Temperature at three
different levels were analyzed using Taguchi L9 orthogonal array. One response i.e. worker’s Heart Rate (HR)
during the each trail of manual material handling (MMH) task was measured. For the optimization of response
the signal-to-noise (S/N) ratio was obtain for each trial. The analysis of S/N ratio and raw data was done by
using analysis of variance (ANOVA) to identify the optimal condition in which response was optimized. Results
shows that the Worker Age was found to be the most significant factor and the Work Time Duration was found to
be least significant factor for heart rate response. The percentage contributions of Worker Age, Work Time
Duration and Workplace Temperature were 73.51%, 3.32% and 18.46% respectively for HR.
Keywords: Signal-to-Noise ratio (S/N), Heart Rate (HR), Manual Material Handling (MMH), Taguchi technique
1. Introduction
Manual Material Handling (MMH) is a general process in all type of manufacturing industries under which the
workers are working in different types of manufacturing tasks like lifting or lowering, carrying and holding etc.
During the Manual Material Handling task the risk factors leading to musculoskeletal disorders (MSDs) are
always present. Physiological measures for assessing physical stresses are necessary for measuring the
expenditure of worker’s energy during the task. Two physiological measures for approximating the physical
stress on the worker are used in experimental research are volume of Oxygen Intake (VO2) and Heart Rate (HR).
Measurement of oxygen intake allows a reliable assessment of physical workload for activities more than five
minutes are marked by Astrand (1977). By calculation the oxygen content of inhaled air at different conditions
of the task a reliable estimate of energy consumption in different trails can be compared. This assessment method
provides a very reliable means for assessing physical stress and can be applied to a range of physical activities. A
second physiological assessment method arises from the measure of heart rate during MMH. The relationship
between the two responses is roughly linear (Corlett, 1986). This linear relationship appears to break down
during very high range of parameters. Several studies provide examples of using heart rate and oxygen intake to
assess MMH work as Wu (1998) examined the differences between symmetrical and asymmetrical MMH lifting
tasks using heart rate data, VO2 and rating of perceived exertion (RPE) and concluded that the maximum
acceptable weight of lift (MAWL) were significantly lower for asymmetric lifting than for symmetric lifting in
the sagittal plane. The MAWL decreased with an increase in the angle of asymmetry, however, the Heart
Rate, Oxygen Intake and RPE remained unchanged, lifting frequency had no significant effect on the percentage
decrease in MAWL from the sagittal plane values and Both the physiological costs (Heart Rate and Oxygen
Intake) and rating of perceived exertion increased with an increase in lifting frequency though maximum
acceptable weight of lift decreased. Wright (1999) concluded that maximum acceptable weight carrying for twohanded
tasks was significantly influenced by age for males as the younger males carried 26% more weight than
older males but the females performing two-handed carrying tasks exhibited no age effect. On the other hand
one-handed carrying tasks were not affected either by age or frequency for both males and females. Marras
(2005) concluded in his research by taking factors of asymmetric lift, different loads and different frequencies in
eight hour shift that spine load increased after the first two hours of lifting exposure regardless of lifting
frequency. Maiti (2006) found the effect of lifting parameters and their interactions on heart rate and also
remarked that the interaction effects between different lifting parameters should be considered in addition to the
effects of individual lifting parameters. Wu (2006) examined the effects of container width, carrying rate, and
distance on the maximum acceptable weight carried (MAWC) by analyze the heart rate and rating of perceived
exertion (RPE) to a 1-hour work period of carrying tasks. Ciriello (2007) studied the effect of high lifting
frequency on maximum acceptable weights of lifting. Sean (2007) in a study on material handling capacity in
different postures examined that heart rate was not significantly affected by posture, but was increased in
asymmetric conditions, lifting/lowering and to/from the high shelf .Oxygen intake was increased by working
posture, lifting/lowering asymmetrically, and when performing the task to the high shelf. Fredericks (2008)
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