It is well known that the faults such as thin-thick, neps and unevenness in the staple yarn make bad the quality of the fabric that is knitted from the yarn. There is a double ply yarn that have neither thin-thick nor neps and no specific cycle in yarn evenness that cause problem in the plain stitch fabric made from flat knitting machine. For comparison, the yarn which has almost same properties on evenness test as the former yarn and makes no problem fabric is selected. In the case of former yarn, the range of the tension which passes through needles on friction test is wider than that of latter yarn and the tension has a certain cyclic variation. The yarn which has certain cyclic tension variation at passing through the needles is made experimentally and is knitted. These results were shown.
