Formulation of Field Data Base Model of Productivity for Standalone Sewing Machine Operation Based on Ergonomic Considerations

Abstract

The sewing machine operator is a most busy operator in culturally different background country like India. The sewing machine operation involves various activities for execution of different tasks. During sewing machine operation the workers performs each type of activity which forms a man–machine system where workers anthropometric data, postures, their skills, motivation, workstation, the working seasons and their workplace influence the performance. This is where their productivity, human energy input, quality and quantity is highlighted. In order to establish relationship amongst input and responses of activity, the mathematical models of sewing machine operation needs to be developed. This article highlights the detailed methodology of mathematical model formulation for the productivity of the standalone sewing machine operation. Present study is done on thirty male sewing machine operators working on manually driven sewing machine from more than last 10 to 12 years in central India. This operation is characterized by a static sitting posture, with forward inclination of head and trunk. Since the operators are sitting on stools without back support, ankle and knee angles are in uncomfortable position. The eyes are constrained towards visual control of work, while the hands are continuously directing the sewing material with the absorption of vibrations on working surface of sewing table. This paper details the formulation of field data based model to analyze the impact of various machining field parameters on the productivity of the sewing machine operation. In all, 39 independent variables are studied to analyze their effect on the dependent variable productivity. The 39 independent variables are then grouped to form 5 dimensionless pi terms using the Buckinham’s Pi Theorem. Further, a model is developed using matrix analysis and the effect of the independent pi terms on the dependent pi term is established. Model derived by combining positive and negative pi terms, further analyzes the effect of the independent variables on the productivity. The models are validated to gauge the accuracy. Formulation of mathematical model and sensitivity analysis reveals that the environmental condition and badly designed stools used for sitting while in working position in the workshop, majorly affects the productivity. Further, to improve productivity, it is necessary that the seating stool used should be properly designed by using ergonomic considerations. Other factors that affect productivity are BMI of the operator and years in operation as well as anthropometric data of the operators.