Abstract
The forces applied on the sewing needles without threads have been measured during penetrating into and withdrawing from fabrics by an Instron type tensile tester at seven levels of needles velocity, ranging from 2 to 400 mm/min. Moreover, observations of deformed states when the needle penetrates into a fabric layer was also studied by using the specially designed apparatus.
Five major variables considered were pressure of presser foot, needle diameter, needle shape, needle velocity, and tensile property of fabrics.
From the results of two experimental methods, it was found that behavior of needles penetrating into fabrics could be characterized by two values : the maximum penetration force and total energy consumed during one penetration and withdrawal cycle. The total energy could be divided in two components ; the strain energy which causes needle holes and fabric deformation in the direction of needle axis, and the frictional energy which generates the heat during sewing.
The needle diameter, needle shape and tensile property of fabric significantly affects magnitude of the strain energy. And, the pressure of presser foot within the normal range in sewing does not affect degree of penetration forces.
