Application
The Yarn Board (Board Winder) is used to assess the evenness, hairiness, neps, and other imperfections in a representative sample of yarn. The yarn is wound at a pre-determined pitch onto a tapered black yarn board. This machine features a variable pitch traverse of 7-19 wraps per centimeter, an adjustable winding speed drive, and is equipped with an alternative pre-tension. It comes with a yarn package stand and five tapered aluminum black yarn boards (250 x 180 mm). Yarn appearance is evaluated visually against photographic comparison standards (not included).
Testing Method
Objective
To determine the appearance quality of yarns made from cotton, man-made fibers, or their blends by winding them onto the blackboard. The method also applies to evaluating carding yarn, combed cotton yarn, air-spun yarn, etc., but is not suitable for woolen yarns.
Yarn Appearance Evaluation
- Slub: A yarn segment with a thicker diameter than the normal yarn diameter, which can be visually identified.
- Thin Place: A segment of yarn with a smaller diameter than normal.
- Shadow: Dark lumps formed by many yarns with thin diameters arranged together.
- Serious Defects: A slub that is 1-2 times thicker than the original yarn and longer than 5 cm, or a thin place that is 0.5 times smaller in diameter than the original yarn and longer than 10 cm.
- Systematic Unevenness: Uneven thickness of yarn that forms a pattern and accounts for more than half of the blackboard surface, with shadows deeper than standard samples.
- Nep: An unbroken particle formed by the winding of one or more fibers.
Testing Procedure
- Place the tester on a stable worktable, connect the power supply, and turn on the machine. Insert the blackboard into the blackboard clip.
- Press the handle to lift the nut from the screw and move it to the fixed position.
- Attach the cop to the cop core, pass the yarn through the guide bar, and wrap it in the blackboard gap.
- Choose the appropriate load weight and place it on the weight tension regulator. Set the gear-shifting of density.
- Press the start button to begin the winding process. The blackboard will rotate, and the yarn will be wound from left to right until the guide bar contacts the limit switch to stop.
- Cut the yarn and remove the blackboard.
Grade Evaluation
- The yarn evenness, neps, and impurity degree are compared with the standard sample to determine the grade.
- Shading and slubs cannot counteract each other, so the lowest grade is taken.
- If the slub is thicker or more frequent than the sample, or if there is serious systematic unevenness, the grade is lowered.
- Serious defects or general systematic unevenness are rated as second or third grade.
