How is woven fabric calculated
1. Quantitative calculation of raw materials:
There are many factors involved in the quantitative calculation of raw materials, and the calculation of many process shrinkage ratios is very complicated. For ease of grasp, a smaller range of values is listed for reference.
1. Warp quantification:
Warp weight per meter (g/m) = warp density per centimeter x finished door width (cm) x (1 + process shrinkage) x (1 + weaving shrinkage) x raw material denier (D) ÷ 9000 (or 1/N, 0.59/s)
2. Quantitative weft:
Quantitative weight of weft per meter (g/m) = finished product width (cm) × weft density per cm × (1+ weft shrinkage) × (1+ process shrinkage) × raw material denier (D) ÷ 9000
The process shrinkage in the above two formulas refers to the raw material shrinkage and twist shrinkage
(1) One of the process shrinkage rate-------raw material shrinkage rate:
Yarn (silk) shrinkage of various properties and processes such as:
The shrinkage rate of mulberry silk soaking process is 1.5%
The shrinkage rate of spun silk dyeing and bleaching process is 2.5%
The natural shrinkage of nylon yarn is 3%
The natural shrinkage of polyester filament is 1.5%
The shrinkage rate of elastic polyester yarn after twisting at high temperature is 7% below 100D
The shrinkage rate of elastic polyester yarn after twisting at high temperature is 8.5% from 101D to 149D
The shrinkage rate of elastic polyester yarn after twisting at high temperature is 10% if it is above 150D
Cotton, linen, viscose staple fiber dyeing, bleaching process shrinkage rate is 2%
The elongation rate of viscose filament after passing through the pulp is 3%
(2) Process shrinkage two --- twist shrinkage:
The silk thread will become shorter after being twisted. This is because the silk thread is twisted from straight to spiral, and the diameter will naturally become thicker when the silk thread becomes shorter. Therefore, when the length is constant, the fineness will become thicker accordingly. Rates are also different. The twist shrinkage rate can be obtained by formula calculation, or you can refer to the commonly used twist shrinkage rate table. Generally, 75D filaments add about 10 twists per centimeter, and the twist shrinkage rate is about 2-3%; 75D filaments add 20 twists per centimeter. Twist about 11-12%; 150D filament is twisted about 10 per centimeter, twist shrinkage is about 5-6%; 150D filament is twisted about 20 per centimeter, twist shrinkage is 13- About 15%
(3) The third process shrinkage rate - warp shrinkage rate:
During weaving, warp threads will form buckling of yarn (silk) threads during interweaving with weft threads, so that a one-meter-long warp thread will not form a one-meter-long cloth after interweaving with weft threads. The ratio of the thread length to the fabric length is the weaving shrinkage rate, and the weaving shrinkage rate can also be calculated by formula. The weaving shrinkage is related to the fineness of the yarn, the density of the weft, and the weaving of the fabric. The thicker the weft (silk) denier, the greater the weaving shrinkage; the greater the weft density of the fabric, the greater the weaving shrinkage; the smaller the number of weaving cycles, the greater the weaving shrinkage. Generally, ordinary products (referring to single-layer fabrics, products whose weft density is not particularly thin or dense) are about 3-8%. (The specific size can be selected between 3-8% according to the above-mentioned fineness, weft density, and organizational structure).
Second, the calculation of fabric weight:
The significance of fabric weight calculation is to understand the approximate weight of the fabric, so that the cost and price of the fabric can be calculated.
Weight per meter: Refers to the weight in grams per meter of finished fabric. The calculation method is:
Weight per meter of finished product (g/m) = (quantitative amount of warp thread × folding rate + quantitative weight of weft thread × folding rate) ÷ dyeing and finishing shrinkage rate
(1) Refining rate:
Net weight of yarn (silk) after dyeing and finishing. Different fibers contain different impurities, and different processes will also make the same raw material have different refining rates. Commonly used raw material refining rates are as follows:
Mulberry silk: 75~80%
Raw mulberry silk: 95~98%
Silk: 90~95%
Dried silk: 88~93%
Viscose, wool: 97%
Cotton yarn, linen: 95% (mercerized, bleached 92%)
Synthetic: 99%
(2) Dyeing and finishing shrinkage:
Dyeing and finishing shrinkage refers to the length ratio of the fabric before and after dyeing and finishing
Dyeing and finishing shrinkage ratio = gray silk weft density ÷ finished product weft density = finished product length ÷ gray silk length
Silk weight per square meter (g/m2)
Silk weight per square meter (g/m2) = silk weight per meter (g) ÷ door width (meter)
3. Calculation of raw material content:
For fabrics that are interwoven or blended with two or more raw materials, the proportion of each raw material contained in it must be calculated, and the calculation method is as follows:
A raw material content = (weight of raw material A × ratio of raw material A × refining rate of raw material A) ÷ (weight of raw material A × refining rate + weight of raw material B × refining rate) × 100%
Example: The warp of a product is 120N/2 silk and hemp blended yarn (70% silk, 30% hemp), and the weft is 40S/2 bright rayon yarn
Finished width: 140cm plain weave
Warp density of finished product: 28 threads/cm Finished weft density: 24 shuttles/cm Weft density of gray silk: 23 shuttles/cm
Secondly, considering several factors, it is estimated that the weaving shrinkage rate is about 5%, the silk shrinkage rate is 2.5%, the weft shrinkage rate is about 10%, and the viscose staple fiber process shrinkage rate is 2.0%, then:
Quantitative warp (g/m) = warp density of finished product × width of finished product × (1+ process shrinkage) × (1+ weaving shrinkage) × raw material fineness ÷ 9000
=28×140×(1+5%)×1/60
=65(g/m)
Quantitative quantity of weft (g/m) = finished weft x finished door width x (1+ weaving shrinkage) x (1+ process shrinkage) x raw material fineness ÷ 9000
=140×24×(1+10%)×0.59/20=109 (g/m)
Finished silk weight per meter (g/m) = (quantitative warp x smelting rate + weft qty x smelting rate) ÷ dyeing and finishing shrinkage
=(65×0.95+109×0.97)÷0.96
=(61.8+105.7=167.5=168(g/m)
Silk weight per square meter (g/m2) = silk weight per meter ÷ door width = 168÷1.4=120(g/m2)
Among them, the raw material content of spun silk = (the weight of spun silk raw material × the proportion of spun silk × the smelting rate of spun silk) ÷ (the weight of spun silk raw material × smelting rate + rayon yarn weight × smelting rate)
=(65×0.7×0.95)÷(70×0.95+109×0.97)×100%=43.2÷167.5×100%=26%
Among them, the content of flax raw materials = (weight of flax raw materials × flax ratio × flax refining rate) ÷ (weight of flax raw materials × refining rate + viscose yarn weight × refining rate)
＝(65×03×0.95×100%)÷65×0.95+109×0.97=18.5×100%÷167.5=11%
Viscose raw material content = (weight of viscose raw material × viscose refining rate) ÷ (weight of warp raw material × refining rate + viscose yarn weight × refining rate)
＝(109×0.97×100%)÷(109×0.97+65×0.95)=105.73×100%÷167.5=63%
Through the above calculations, it can be concluded that the warp raw material of this product is 65g per meter; the weft raw material is 109g per meter. On this basis, a certain percentage of silk return rate is added according to the product process (white weaving, yarn-dyed weaving, sliver, lattice) , combined with the market price of raw materials, a more accurate cost of raw materials can be obtained, plus weaving and dyeing labor costs, which is the base price of the product.