How to calculate the weight of fabric
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, and use a steel ruler to measure its length and width (cm) , then find the area (square centimeters) of the gray fabric sample after cutting, and weigh it on the balance (milligrams)
Gram weight of sample fabric per square meter = weight ÷ 1000 ÷ (area ÷ 10000) = weight ÷ area × 10;
1. Calculation methods and tools are used together
For example: a sample cloth is 7 cm long, 8 cm wide, and weighs 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 cutting sampling knife, place the fabric sample underneath, rotate it clockwise a few times, and take three circular sample fabrics on the gray fabric (20CM outside the edge or tail of the fabric) Take) and weigh it on an electronic balance to measure the specific data.
2. Calculate the gram weight of color cloth
Grain fabric weight refers to the weight per unit area of 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, finished product width, and finishing process. Simple calculation of gram weight:
1. Non-elastic cloth color cloth weight calculation:
(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 weight is approximately 242-248g/m2.
2.The weight of the finished elastic fabric
On-machine reed width/finished door width* (on-machine density/warp count*22.17 + gray fabric weft density/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 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 Compare the weight of the gray cloth with the weight of the weighed finished cloth sample. 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:
Under normal circumstances, the difference within ±5 grams is more normal.
If the difference is large, analysis is required. The principle is as follows: the difference of combed compact yarn is slightly smaller.
( 1 ) Polyester-cotton or polyester-nylon blended yarn and chemical fiber yarn have conversion constants greater than 583.1 of pure cotton. For the same yarn count, If the number is larger, the calculated weight is smaller than the actual weight;
( 2) Stranded yarn is made of two or more single yarns twisted together. Due to the twist shrinkage, the actual yarn The 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, which loses more during pre-treatment and scouring during printing and dyeing, so its calculated weight is heavier than the actual weighing;
( 4 ) After washing, the weight is about 5-6.5% larger;
( 5 ) Due to the weight of the dye when dyeing dark colors, 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
① Excessive pre-treatment stretching 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.
④ When purchasing raw yarn, the yarn is too thin. For example, the actual measurement of 40S is only 41S.
⑤ The original 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 scratching process and sanding process.
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