8 reasons for lack of weight in fabrics

One. Weight

Analyze whether the yarn branch and density are correct, cut the two warp yarns and two weft yarns along the four sides of the sample fabric into rectangles or squares, measure the length and width (cm) with a steel ruler, and then calculate the area after shearing the grey fabric sample (Square Cm) and put the weight (mg number) on the balance. The grammage of a fabric refers to the weight per unit area of ​​the fabric, generally expressed in grams per square meter (g/m2) or ounces per square yard (oz/Y2). The actual grammage is related to the distribution of cotton, yarn thickness, finished door width and finishing process.

Sample cloth weight per square meter = weight ÷ 1000 ÷ (area ÷ 10000) = weight ÷ area × 10;

Differences within ±5 grams under normal circumstances are within normal limits. Large differences need to be carefully analyzed, according to our many years of experience to summarize the laws:

Under normal circumstances, the difference within ± 5 grams is more normal.

If the difference is large, it needs to be analyzed. The principle is as follows: The difference between combed compact yarns is slightly smaller.

(1) Polyester / cotton or polyester / cotton blended yarns and man-made fiber yarns are all larger than the value of 583.1 for pure cotton because their conversion constants are larger than those of pure cotton. The number of identical yarns is larger, and the calculated weight is smaller than the actual weight;

(2) The strand is formed by twisting two or more single yarns in parallel. Due to shrinkage, the actual yarn is coarse, the calculated weight is smaller than the actual weight, and the warp and weft yarns are all strands. ,big different;

(3) Air-jet spinning is a kind of short-fiber yarn, which has more loss in pre-processing scouring during printing and dyeing, and its calculated weight is greater than actual weight;

(4) About 5-6.5% of grammage after washing;

(5) When the dyeing is dark, the calculated weight is slightly larger than the actual weight due to the weight of the dye;

(6) The calculated weight of bleached blanks and light colored blanks is slightly greater than the actual weight;

(7) Weight-average weight after coating is 3-7%;

(8) 3.5-6% lighter weight after grinding;

Second, reduce the weight of the finished product

1 The pre-treatment stretches too much and the assembly reduces the weft density.

2 The width of the finished door is too wide.

3 If the alkali concentration is too high and the processing temperature is too high in the subsequent steps, yarn fibers may be damaged.

4 When the original yarn is purchased, the yarn is fine. For example, 40S actually measures 41S.

5 The original yarn wears too much during the weaving process, which will cause too much hairiness to fall off and lead to finer yarns resulting in lower grammage.

6 Re-coloring and stripping during the dyeing process will result in a large loss of yarn and a reduction in yarn weaving.

7 In the process of singeing, excessive singeing fire force causes the cloth surface to be too dry, and the yarn is damaged when the desizing process is performed.

8 Damage to the fabric during the finishing process and the finishing process.

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