Finger Pinch Loosening and Tightening Torques on Small Cylindrical Handles Among Industrial Workers
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Abstract
An experiment was conducted with 23 assembly line workers in a manufacturing plant to study to the variation in finger torque strengths on small handles. Subjects exerted MVC torques on small cylindrical handles with different finger contact surface finishes (smooth and knurled) and different diameters (3.3, 5.0, 6.4, 9.5, and 19.0 mm). Three similar handles with flanged finger contact were also tested to simulate torqueing on a specific medical device. The flange widths were 6.4, 9.5, and 19.0 cm. Both loosening and tightening peak torques were measured. Ten males and 13 females between the ages of 22 and 55 years were tested. Each performed 26 different torque exertions while standing (20 on cylinders and 6 on flanges). The results indicated that finger torque strength decreased steadily as diameter of the cylindrical handle, or length of the flange, decreased. It was also stronger for tightening compared to loosening, and for knurled cylinders compared with smooth cylinders. Of greater interest was the 2-factor interaction effects on torque – surface*direction, surface*diameter and diameter*direction for the cylinders; and direction*width for the flanges. These interactions indicate that the change in torque over one torqueing factor is not independent of other factors. These results have implications for the design of small device parts, as in some types of medical products.
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Sheik N Imrhan, Department of Industrial and Manufacturing Systems Engineering University of Texas at Arlington Arlington, Texas 76013
Associate Professor, Industrial and Manufacturing Systems Engineering Dept.References
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