(1) Bulk density: reflects the characteristics of fiber stacking;
(2) The twist angle and curl of the fiber: reflect the straightness of the fiber along the yarn shaft;
(3) The number of strands and twist direction:
(4) Thread density (diameter) and coefficient of variation: reflect the thickness and change of yarn
(5) The force between the fibers (friction factor, entanglement point, action fragment or slip length, etc.): reflects the stability of the yarn structure