1. It is stipulated that cotton yarn should be tested according to the specified test cycle and various test methods, and the quality of cotton yarn should be evaluated according to the results.
2. The quality of cotton yarn is divided into superior, first class and second class, and those lower than the second class index are classified as third class, also called substandard.
3. The grade of cotton yarn is evaluated by the coefficient of variation of single yarn breaking strength CV (%) and the coefficient of variation of 100-meter weight CV (%), the evenness, the number of neps in one gram and the total number of neps and impurities in one gram. When the grade of the five items is different, the grade of the lowest of the five items is evaluated.
4. The grade of cotton thread is evaluated by the coefficient of variation of breaking strength of single thread CV (%), the coefficient of variation of 100-meter weight CV (%), the number of neps in one gram and the total number of neps and impurities in one gram. When the grade of the four items is different, the grade of the lowest of the four items is evaluated.
5. When the breaking strength of single yarn (thread) or the weight deviation of 100 meters exceeds the allowable range, the breaking strength variation coefficient CV (%) of single yarn (thread) and the weight variation coefficient CV (%) of 100 meters shall be reduced by one grade on the basis of the original rating. If both of them are beyond the range, they shall also be reduced by one grade. To the second class.
6. Superior cotton yarn plus 100000 meter yarn defect is also used as grading index.
7. The manufacturer can select either the evenness of black board or the variation coefficient CV (%) of evenness of black board for evenness inspection. However, once confirmed, it shall not be arbitrarily changed. In case of quality dispute, the evenness variation coefficient CV (%) shall prevail.
8. The monthly cumulative weight deviation of cotton yarn shall be weighted and averaged according to the output. The varieties produced in more than 15 batches in the whole month shall be controlled within 0.5% of the soil.
