Visual determination of unevenness along the length of a yarn is carried out by wrapping it in equally spaced parallel wraps over a board and comparing the appearance of irregularities against standard rating photographs.
To enable yarns of different thickness to be assessed, the spacing between the warps is suitably selected so as to give a clearly distinguishable pattern.
The Yarn Evenness Tester consists of a yarn warp board and an arrangement to wrap the yarn over it at equal spacing under a desired tension. The board is rotated manual to warp yarn over it. The yarn is guided on to the board through a yarn guide, which moves parallel to the pivoting axis of the board with the help of a screw giving uniformly spaced wraps. The guide is positively linked to the rotation of the board with the help of a chain and sprocket drive. A set of change gears gives five different spacing for wrapping yarn of different counts. A spring loaded adjustable tensioning arrangement provides the desired tension to the yarn.
ASTM D 2255 – 1964 : Standard Method for Grading of Cotton Yarns for