For fabric designers, fabric specification calculation is the basis for guiding factories to produce products. For salesmen, it is a means of communicating with customers, quoting prices, and controlling costs. Once you have mastered this knowledge, you can calculate the price of the product in the shortest possible time, no matter what type of product you are on. Basic cost, ensure accurate and timely quotation, and grasp the key to cost control.
01
Raw material quantitative calculation
There are many factors involved in the quantitative calculation of raw materials, and the calculation of many process shrinkage rates is very complicated. For ease of understanding, a smaller range of values is listed for reference.
1. Quantification of longitude:
Warp weight per meter (g/m) = warp density per cm 0.59/s)
2. Quantification of weft lines:
Basis of weft per meter (g/m) = finished product width (cm) × weft density per centimeter × (1 + weft shrinkage) × (1 + process shrinkage) × raw material fiber size (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 rates ——- raw material shrinkage rate:
The shrinkage rates of yarns (filaments) with different properties and different processes are as follows:
The shrinkage rate of mulberry silk soaking process is 1.5%
The shrinkage rate of silk dyeing and bleaching processes is 2.5%
The natural shrinkage rate of nylon yarn is 3%
The natural shrinkage rate of polyester filament is 1.5%
The high temperature setting shrinkage of elastic polyester yarn after twisting is 7% below 100D.
After twisting the elastic polyester yarn, the high temperature setting shrinkage of 101D~149D is 8.5%
After twisting the elastic polyester yarn, the high temperature setting shrinkage is 10% above 150D.
The shrinkage rate of cotton, linen and viscose staple fiber dyeing and bleaching processes is 2%
The elongation of viscose filament after passing through machine pulp is 3%
(2) Process shrinkage rate 2——Twist shrinkage rate:
The silk thread will become shorter after twisting. This is because the silk thread changes from straight to spiral twist. As the silk thread becomes shorter, the diameter will naturally become thicker. Therefore, when the length is constant, the fineness will become correspondingly thicker. The twisting shrinkage of different fineness and different twists Rates are also different. The twist rate can be obtained through formula calculation, or you can check the commonly used twist rate table. Generally, 75D filament adds about 10 twists per centimeter, and the twist rate is about 2-3%; 75D filament adds 20 twists per centimeter. The twist is about 11-12%; the 150D filament has about 10 twists per centimeter, and the twist shrinkage is about 5-6%; the 150D filament has about 20 twists per centimeter, and the twist shrinkage is about 13- About 15%
(3) The third process shrinkage rate – meridional shrinkage rate:
During weaving, the warp threads will buckle in the yarn (silk) during the interweaving process with the weft threads. In this way, a one-meter-long warp thread will no longer form a one-meter-long cloth after being intertwined with the weft threads. The ratio of the silk thread length to the fabric length is the weaving shrinkage rate, and the weaving shrinkage rate can also be calculated through formula calculation. The size of the weaving shrinkage is related to the yarn’s fineness, weft density, and fabric structure. The thicker the weft (filament) fineness, the greater the weaving shrinkage; the greater the weft density of the fabric, the greater the weaving shrinkage; the smaller the number of tissue cycles, the greater the weaving shrinkage. Generally, ordinary products (referring to single-layer fabrics with weft density that is not particularly thin or dense) are around 3-8%. (The specific size can be selected between 3-8% based on the fineness, weft density, and tissue structure mentioned above).
02
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:
Finished product weight per meter (g/m) = (warp weight × folding rate + weft weight × folding rate) ÷ dyeing and finishing shrinkage rate
(1) Refining discount rate:
The net weight of yarn (silk) after dyeing and finishing. Different fibers contain different impurities, and different processes will also result in different refining rates of the same raw material. Commonly used raw material refining rates are as follows:
Mulberry silk: 75~80%
Raw mulberry silk: 95~98%
Silk: 90~95%
Tsumugi silk: 88~93%
Viscose, wool: 97%
Cotton yarn, linen: 95% (mercerized, bleached 92%)
Synthetic fiber: 99%
(2) Dyeing and finishing shrinkage rate:
Dyeing and finishing shrinkage refers to the length ratio of the fabric before and after dyeing and finishing
Dyeing and finishing shrinkage rate = weft density of raw silk ÷ weft density of finished product = length of finished product ÷ length of raw silk
Square meter silk weight (g/m2)
Silk weight per square meter (g/m2) = Silk weight per meter (g) ÷ Door width (m)
03
Raw material content calculation
For fabrics that are interwoven or blended from two or more raw materials, the proportion of each raw material contained in it must be calculated. The calculation method is as follows:
Content of raw material A = (weight of raw material containing A × proportion of raw material A × refining rate of raw material A) ÷ (weight of raw material containing A × refining rate + weight of raw material B × refining rate) × 100%
Example: The warp of a product is 120N/2 silk and linen blended yarn (70% silk, 30% linen), and the weft is 40S/2 glossy rayon yarn
Finished door width: 140cm plain weave��weaving
Finished warp density: 28 threads/cm. Finished product weft density: 24 threads/cm. Raw silk weft density: 23 threads/cm.
Secondly, based on several factors, it is estimated that the weaving shrinkage rate is about 5%, the silk process shrinkage rate is 2.5%, the weft shrinkage rate is about 10%, and the viscose staple fiber process shrinkage rate is 2.0%, then:
Warp basis weight (g/m) = finished product warp density × finished product width × (1 + process shrinkage) × (1 + weaving shrinkage) × raw material fineness ÷ 9000
=28×140×(1+5%)×1/60
=65(g/m)
Weft thread basis weight (g/m) = finished weft × finished door width × (1 + weaving shrinkage in the weft direction) × (1 + process shrinkage) × raw material fineness ÷ 9000
=140×24×(1+10%)×0.59/20=109(g/m)
Finished silk weight per meter (g/m) = (warp weight × refining fold rate + weft weight × refining fold rate) ÷ dyeing and finishing shrinkage rate
=(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 content of spun silk raw materials = (weight of raw materials containing spun silk × proportion of spun silk x refining and folding rate of spun silk) ÷ (weight of raw materials containing spun silk × refining and folding rate + weight of rayon yarn × refining and folding 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 proportion × 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 and folding rate) ÷ (weight of warp raw material × refining and folding rate + viscose yarn weight × refining and folding 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 ration of this product is 65g per meter; the weft raw material ration is 109g per meter. On this basis, a certain proportion of yarn recovery rate is added according to the product process (white weaving, yarn-dyed weaving, sliver, plaid) , combined with the market price of raw materials, a more accurate raw material cost can be obtained, plus the weaving and dyeing labor costs, it is the base price of the product.
(PS: The word “weight” in the article is the traditional term, and the standard term should be “quality”)
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