Yarn quality The assessment mainly includes two aspects: intrinsic quality and appearance quality: Main indicators of cotton yarn rating: 1. Variation coefficient of single yarn breaking stren...
Yarn quality The assessment mainly includes two aspects: intrinsic quality and appearance quality:
Main indicators of cotton yarn rating:
1. Variation coefficient of single yarn breaking strength.
2. Coefficient of variation of weight per 100 meters.
3. Evenness of evenness.
4. The number of neps in one gram.
5. The total number of neps and impurities in one gram.
6. One hundred thousand meters of yarn defects.
Basis of cotton thread rating: 1.2.4.5.
Rating method: Based on the lowest one from 1 to 5, and then look at 1.2. Whether it is out of range, regardless of one or two items If it exceeds the standard, it will be downgraded to the first grade, and for this purpose, an additional 100,000 meters of yarn defects will be added as a grading index for high-quality cotton yarn.
Single yarn is measured 60 times and strands are measured 30 times. It can be obtained by substituting into the coefficient of variation formula. The formulas for n>50 or n<50 are different.
30 yarns, 1 meter long per week, 100 weeks. 30 are weighed separately and substituted into the coefficient of variation formula. Accordingly, search the product, etc. in the technical specification table.
Actual features and design features.
The deviation percentage between the two is called weight deviation or special number deviation. In actual evaluation, it is measured by the weight deviation of 100 meters.
You can use the coefficient of variation of evenness (measured with an electronic uniformity meter) or the uniformity of blackboard evenness If there is any dispute between the two, the former shall prevail. Determination of blackboard dryness uniformity: Randomly select 10 tubes and shake 10 blackboards evenly. 250mmx220mm, compare them with the standard photos in turn under the specified light, and evaluate them as excellent or good according to their shadows, thick spots, serious defects, serious regular unevenness, etc. Those that are equal to or equal to first grade will be rated as first grade, those that are worse than first grade or have serious defects will be rated as second grade, and those with serious regularity and unevenness will be rated as third grade based on 10. The proportion of first-class, first-class, second-class, and third-class blackboards determines their evenness.
The number of neps and impurities within 10 spaces on the front and back of the point, the total number of neps na and the total number of neps and impurities nb within 10 blackboards can be calculated as follows:
The number of neps in 1g=na/ Ntex x10
Total number of neps and impurities within 1g = (na+nb)/Ntex x10
Yarn defects refer to major defects attached to the yarn, which are divided into short slubs (more than 100% thicker than normal and less than 200px in length), long slugs (more than 45% thicker than normal and more than 200px in length). Long thin knot ( 30~70% thinner than normal and longer than 200px). It affects the quality of the cloth and causes short ends. The inspection requires a large sample size, otherwise it is difficult to detect, so it is carried out on a yarn defect meter of 100,000 meters. /span>
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