Insufficient fabric weight is not a big problem and has little impact on regular trade. However, when it comes to export orders or specific trade, the weight is often the most critical link. A large order was placed, but in the end the order was canceled or claimed due to insufficient weight. The following explains the reasons for insufficient weight.
1. Gram weight
Analyze whether the yarn count and density are correct. Cut the two warp yarns and two weft yarns along the four sides of the sample into a rectangle or square. Use a steel ruler to measure its length and width (cm), and then find the area of the gray fabric sample after cutting (square meters). cm), and weigh it on the balance (milligrams)
Gram weight of sample cloth per square meter = weight ÷ 1000 ÷ (area ÷ 10000) = weight ÷ area × 10 ;
1. Use calculation methods and tools together
For example: a piece of fabric is 7 cm long , 8 cm wide, weighing 772 mg, then the finished product has a gram weight per square meter = 772 ÷ (7 × 8) × 10 = 138 grams
2. Tool method
Use a circular disk to cut the sampling knife, put the cloth sample underneath, rotate it clockwise a few times, and take a circular shape on the gray cloth Sample the fabric in three places (take it from the edge or 20cm away from the tail) and weigh it on an electronic balance to measure the specific data.
2. Calculate the weight of color cloth
Grain fabric weight 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 gram weight is closely related to the cotton mix, yarn count thickness, finished product width, and finishing process. Simple calculation of gram weight:
1. Calculation of weight of non-elastic fabric:
(grey cloth warp density/warp count + gray cloth weft density/weft count)*24.3
For example: Calculate the gram weight of 20*16 / 128*60/63〞.
（128/20 + 60/16）*24.3≈246.6(g /m2)
The gram weight is about 242-248g/m2.
2. The gram weight of the finished elastic fabric
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Reed width on the machine/finished door width* (density on the machine/warp count*22.17 + weft density of gray fabric/weft count*21.4)
For example: Calculate variety C78〞 20*16+70D / 116*48 Gram weight
78/58* (116/20*22.17+48/16*21.4 )≈259 (g/m2)
The actual gram weight is about 260-265g/m2.
Note: 78″ is the reed width on the machine, and the finished door width is 58″
3. Simple calculation and weighing
Simple calculation formula: gray cloth weight and weighed finished cloth Comparing the sample weight, under normal circumstances, the difference within ±5 grams is within the normal range. Large differences require careful analysis. Based on our many years of experience, we have summarized a few rules:
Generally, differences within ±5 grams are more normal.
If the difference is large, analysis is required. The principle is as follows: the difference between combed compact yarn is slightly smaller.
(1) Since the conversion constants of polyester-cotton or polyester-nylon blended yarns and chemical fiber yarns are larger than 583.1 of pure cotton, the yarns of the same count have larger numbers. The calculated weight is certainly smaller than the actual weight;
(2) The stranded yarn is made of two or more single yarns and twisted together. Due to the twisting and shrinkage The reason is that the actual yarn count is thicker and the calculated weight is smaller than the actual weight. When the warp and weft yarns are both strands, the difference is larger;
(3) Open-end spinning is a short fiber yarn , there is a lot of loss during pre-treatment and scouring during printing and dyeing, and the calculated weight is heavier than the actual weighing;
(4) The weight after washing is about 5-6.5% larger;
(5) When dyeing dark colors, due to the weight of the dye, the calculated weight is slightly larger than the actual weighing;
(6) The calculated weight of bleached blanks and light-colored blanks is slightly larger than the actual weight;
(7) The weight after coating is 3-7% heavier;
(8) The weight after grinding is 3.5-6% lighter;
4. Reasons for the reduction in finished product weight
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① Excessive stretching in pre-treatment will cause the weft density to decrease.
②The finished door width is too wide.
③ Excessive alkali concentration and excessive post-processing temperature will cause damage to the yarn fibers.
④When purchasing the raw yarn, the yarn is too thin. For example, the actual measurement of 40S is only 41S.
⑤ The raw yarn is greatly worn during the weaving process, which will cause excessive hairiness to fall off, resulting in thinning of the yarn and low weight.
⑥Re-changing and stripping colors during the dyeing process will cause large yarn losses and cause the yarn to become thinner.
⑦ During the singeing process, the excessive firepower of the singeing will cause the cloth surface to be too dry, and the yarn will be damaged during desizing, causing it to become thinner.
⑧ Damage to the cloth surface during the catching and sanding processes. </p
