In this study a new thread testing system is proposed to evaluate the sewability of sewing thread.
From the point of view of machine sewing it is requested that sewing threads are tested under the condition of high speed, cyclic loading. In the testing system proposed here, a sample yarn is stretched and relaxed by a pair of clamps along the yarn direction in the cyclic way. A tension regulator, driven by a servomotor controlled with a computer system, is placed between two clamps for keeping the tension peak unchanged through the testing procedure. Control data are prepared by the method of trial and error in advance, because the changing speed in tension cycle is too high to control with a feed-back system.
The cyclic loading test was successfully performed using the system mentioned above. The changes in the residual strain and the work of threads are easily calculated from the data obtained by the system. Especially the work obtained from the relaxing process could be one of the most important factor for evaluating the sewability of sewing thread. The relation between the test results and the sewability will be discussed in the next paper.