Due to the different textures used in the fabrics, the arrangement of colored yarns, the raw materials and characteristics of the yarns, the density of the yarns, the twist direction and degree of twist of the yarns, the structure of the yarns and the finishing methods, etc. The result is a different appearance of the fabric.
In order to produce, innovate or imitate products, it is necessary to master information such as fabric structure and fabric machine technical conditions. For this reason, fabrics must be analyzed thoughtfully and carefully in order to obtain correct analysis results and provide information for designing, transforming or imitating fabrics.
In order to obtain more accurate analysis results, the items to be analyzed and their sequence must be planned before analysis. The operation process must be meticulous, and the fabric sample materials must be saved as much as possible while satisfying the analysis conditions.
Fabric analysis is generally performed in the following order.
One: Sampling
When analyzing fabrics, the accuracy of the data is related to the location of the sampling and the size of the sample, so there should be certain regulations on the sampling method. Since there are so many types of fabrics and they are very different from each other, in practice, The selection of samples during work should also be determined according to the specific situation
(1) Sampling position
After the fabric is off the machine, the width and length of the fabric change slightly due to the balancing effect of the warp and weft yarn tension. This change causes differences in the density of the edges and middle of the fabric, as well as the two ends of the fabric. . In addition, during the dyeing and finishing process, the two ends, edges and middle of the fabric also undergo different changes. Similarly, in order to make the measured data accurate and representative, it is generally stipulated that when sampling from the entire fabric, the distance from the sample to the edge of the fabric is not less than 5cm, and the distance from both ends is not less than 1.5-3m on cotton fabrics; Not less than 3m on wool fabrics; about 3.5-5m on silk fabrics
In addition, the sample should not have obvious defects and strive to be in its original natural state to ensure the accuracy of the analysis results.
(2) Sampling size
The size of the sampling area should vary with the type of fabric and the structure of the fabric. Since fabric analysis is a consumption test, we should strive to reduce the size of the sample in the spirit of economy and on the premise of ensuring that the analysis data is correct. Simple The fabric sample of the tissue can be smaller, usually 15cm*15cm. The colored fabric with larger tissue circulation can be 20cm*20cm. Fabrics with large loops (such as bed sheets) should take at least the area occupied by one colored yarn loop. For large jacquards (such as quilts and carpets), because the number of warp and weft yarn loops is large, it is generally sufficient to analyze some representative tissue structures. . Therefore, it is generally taken as 20cm*20cm, or 25cm*25cm. If the sample size is small, it can be analyzed as long as it is slightly larger than 5cm*5cm.
Second: Determine the front and back of the fabric
When analyzing cloth samples, first determine the front and back sides of the fabric.
The front and back sides of a fabric are generally judged based on its appearance. Here are some commonly used judgment methods.
1. Generally, the patterns and colors on the front side of fabrics are clearer and more beautiful than those on the reverse side.
2. The front pattern of plants and color-matching patterned fabrics with a striped appearance must be clear and pleasing to the eye.
3. The front side of convex and concave-convex fabrics is tight and delicate, with strips or patterned ridges, while the reverse side is rougher and has longer floating lines.
4. Raised fabric: Single-sided raised fabric, its raised fabric The pile side is the front side of the fabric. For double-sided pile fabrics, the side with smooth and neat pile is the front side.
5. Observe the edge of the fabric: If the edge of the fabric is smooth and clean, the neat side is the front of the fabric.
6. Double layer, multi-layer and multiple fabrics, if the latitude and longitude densities of the front and back are different, the front generally has a greater density or the material of the front is better.
7. Leno fabric: The side with clear texture and protruding warp is the front side of the fabric.
8. Towel fabric: Take the side with higher terry density as the front.
Most fabrics have obvious differences between the front and back sides, but there are also many fabrics whose front and back sides are very similar and can be used on both sides. Therefore, it is not necessary to distinguish the front and back sides of such fabrics.
Three: Determine the warp and weft directions of the fabric
After determining the front and back of the fabric, it is necessary to determine which direction is the warp yarn and which direction is the weft yarn in the fabric. This is important for analyzing items such as fabric density, warp and weft yarn characteristics, and fabric weave. Prerequisites.
The main basis for distinguishing the warp and weft directions of fabrics is as follows.
1. If the sample of the fabric being analyzed is selvedge, the yarns parallel to the selvedge are warp yarns, and the yarns perpendicular to the selvedge are warp yarns. Weft.
2. Warp yarns contain sizing, and weft yarns do not contain sizing.
3. Generally, the side with higher fabric density is the warp yarn, and the smaller side is the weft yarn.
4. For fabrics with obvious reed marks, the direction of the reed marks is the warp direction of the fabric
5. When one group of yarns in the fabric is a strand and the other group is a single yarn, the strands are usually warp yarns and the single yarns are weft yarns.
6. If the yarn twist directions of the single yarn fabric are different, the Z-twisted yarn is in the warp direction and the S-twisted yarn is in the weft direction.
7. If the twists of the fabric yarns are different, the twists will mostly be in the warp direction and the twists in the smaller ones will be in the weft direction.
8. If the warp and weft yarns of the fabric have little difference in the special number, twist direction, and twist direction, then the yarn The threads are even and shiny. The warp yarns are the ones with better luster
9. Towel fabrics with terry yarns is the warp yarn, and the terry-free yarn is the weft yarn.
10. The strip direction of strip fabric is usually the warp direction.
22. If the fabric has a system of yarns with multiple When the number is different, this direction is the meridional direction.
12. Leno fabric, twisted yarns are warp yarns, and untwisted yarns are weft yarns.
13. In the interweaving of different raw materials, generally cotton is the warp yarn in the interwoven fabric of cotton, wool and cotton and linen; in the interwoven wool and silk fabric, the silk is the warp yarn; in the interwoven wool and silk cotton fabric, the silk and cotton are the warp yarns; In the interweaving of natural silk and silk silk, the natural silk is the warp yarn; in the interweaving of natural silk and rayon silk, the natural silk is the warp yarn.
Since fabrics have a wide range of uses, they also have many requirements for fabric raw materials and organizational structures. There are various types, so when judging, it should be determined according to the specific conditions of the fabric.
Four: Determine the warp and weft density of the fabric
On fabricThe number of warp and weft yarns arranged in unit length is called the warp and weft yarn density of the fabric.
The calculation unit of fabric density is in metric system, which refers to the number of warp and weft yarns arranged within 10cm. The density directly affects the physical and mechanical indicators of the fabric such as appearance, feel, thickness, strength, flexural resistance, air permeability, abrasion resistance and thermal insulation performance. It is also related to the cost and production efficiency of the product.
There are two methods for measuring the longitude and weft density.
(1) Direct number measurement method
The direct measurement method is accomplished by relying on a cloth mirror or a fabric density analysis mirror. The length of the scale of the fabric density analysis mirror is 5cm. Under the analysis lens, a long strip of glass is engraved with a red line. When analyzing fabric density, move the mirror First, align the red line on the glass plate and the red line on the scale between two yarns at the same time. Use this as a starting point and count the number of yarns while moving the camera until the 5cm scale line reaches the output number of yarns. Multiply by 2 to get the density value of 10cm fabric.
When counting the number of yarns, the center between the two yarns should be used as the starting point. If the count reaches the end point, it exceeds 0.5 and is less than one, it should be counted as 0.75; if it is less than When the number is 0.5, it is calculated as 0.25. Generally, 3-4 data should be measured for fabric density, and then the arithmetic average is taken as the measurement result.
(2) Indirect testing method
This method is suitable for fabrics with high density and regular weave with small yarn characteristics. First, after analyzing the fabric structure and the number of weft loops (number of weft loops), then Multiply by the number of weave loops in 10cm, and the resulting product is the warp (weft) yarn density.
Five: Determine warp and weft yarn shrinkage
The warp and weft yarn shrinkage is one of the structural parameters of the fabric. The purpose of measuring the warp and weft yarn shrinkage is to calculate the specific number of the yarn and the amount of yarn used in the fabric. Since the yarn is formed into the fabric, the warp and weft yarn shrinkage are The (weft) yarns are staggered and buckled in the fabric, so the length of the yarn used in weaving is greater than the length of the fabric. Therefore, the ratio of the difference to the original length is called shrinkage.
Straight length-sample middle length)/straight length
The size of the warp and weft yarn shrinkage is An important basis for process design, it has a great influence on the amount of yarn, the physical and mechanical properties of the fabric and the appearance of the fabric.
There are many factors that affect the shrinkage rate. Differences in fabric structure, warp and weft yarn raw materials and special numbers, warp and weft yarn density, and yarn tension during the weaving process will all cause changes in shrinkage rate.
When analyzing fabrics, the method for measuring shrinkage is generally to take a 10cm length of fabric along the warp (weft) vector at the edge of the sample and mark it (when the sample is small, a length of 5cm can be measured ), cut the yarn tassel at the edge short (this can reduce the external elongation of the yarn when it is pulled out of the fabric), then gently pull out the warp (weft) yarn from the sample, and press the yarn with your fingers one end, use the other hand to gently Gently straighten the yarn (the tension must be appropriate and there should be no stretching). Use a ruler to measure the length of the warp (weft) yarn between the marks. After making ten consecutive numbers, take the average value and enter it into the above formula. , the shrinkage value of the warp or weft yarn can be obtained. This method is simple and easy to implement, but the accuracy is poor. The purpose of measuring the yarn shrinkage is to calculate the yarn characteristics and the yarn amount of the fabric. The following points should be noted:
1. When pulling out and straightening the yarn, do not use The yarn is untwisted or twisted. For some yarns with small twist or poor strength, the warp should be measured to avoid accidental elongation.
2. When analyzing scraped and milled fabrics, you should first use scissors or matches to remove the fluff on the surface, and then carefully pull the yarn out of the fabric.
3. Viscose fiber is easy to stretch when wet, so avoid getting the yarn wet with sweat when operating.
Six: Calculate the special number of warp and weft yarns
Yarn uses tex to express its fineness. Yarn tex is the weight in grams of 1000m yarn at a common moisture regain. The calculation formula is as follows: tex=1000G/L
tex represents the special number of warp or weft yarns; G represents the public moisture regain Weight (g); L represents length (m)
There are generally two methods for measuring yarn characteristics.
1. Comparative measurement method: This method is to place the yarn under a magnifying glass, carefully compare it with yarns with known characteristics, and then determine the characteristics of the warp and weft yarns. The accuracy of this method is the same as that of yarns with known characteristics. It is related to the experience of testers. Because the method is simple and fast, factory testers are often willing to use it.
2. Weighing method: Before measuring, it is necessary to check whether the warp of the sample is sized. If If the warp is sized, the pattern should be desized.
When measuring, take out 10 warp yarns and 10 weft yarns from the 10cm*10cm fabric and call them respectively Weight. Measure the actual moisture regain of the fabric. Under the condition that the warp and weft yarn shrinkage is known, the warp and weft yarn characteristics can be calculated by the following formula:
tex=G(1- a)(1+W~)/(1+W)
G represents 10 actual warp or weft yarns Weight; a represents warp or weftShrinkage; W represents the actual moisture regain of the fabric; W~ represents the official moisture regain of this type of yarn.
The following are the official moisture regains (%) of various yarns: cotton 8.5; viscose 13; combed wool yarn 16; carded wool yarn 15; acrylic 2; acetate 7; spun silk 22; polyester 0.4; nylon 4.5; vinylon 5; polypropylene 0
Seven: Fixed warp and weft yarn raw materials
Correct and reasonable selection of raw materials for various types of fabrics, It plays an extremely important role in meeting various uses. Therefore, there are two main aspects to analyze the warp and weft yarn raw materials. style=”margin: 0px; padding: 0px; max-width: 100%; clear: both; min-height: 1em; white-space: pre-wrap; color: rgb(62, 62, 62); font-family : ‘Helvetica Neue’, Helvetica, ‘Hiragino Sans GB’, ‘Microsoft YaHei’, Arial, sans-serif; font-size: 16px; line-height: 25.6000003814697px; box-sizing: border-box !important; word-wrap: break-word !important; background-color: rgb(255, 255, 255);”> 1. Qualitative analysis of fabric warp and weft yarn raw materials The purpose is to analyze the raw material composition of the fabric yarn, that is, to analyze whether the fabric is a pure woven fabric, a blended fabric, or a woven fabric. The general step to identify the fiber is to first determine the type of fiber, whether it is a natural cellulose fiber or a natural fiber. Protein fiber or chemical fiber. Determine which type it is. Commonly used identification methods include hand visual inspection, combustion method, microscopy method, chemical dissolution method, etc. The specific methods are the same as the fiber identification method.
2. Quantitative analysis of blended fabric components This is an analysis of the content of the fabric. The dissolution method is generally used. It selects an appropriate solvent to dissolve one of the fibers in the blended fabric, weighs the remaining fiber, and thus knows the weight of the dissolved fiber, and then calculates the mixture. Percent.
The specific method is the same as the blended yarn content analysis method.
Eight: Estimated fabric weight
Fabric weight refers to the sizing-free dry weight in grams per square meter of fabric. It is an important technical indicator of fabric. It is also the main indicator of economic accounting for fabrics. According to the size and specificity of the fabric sample There are two test methods:
1．Weighing method When measuring the weight of fabrics using this method, tools such as a torsion balance and analytical balance should be used. When measuring the weight of the fabric per square meter, the larger the area of the sample, the more accurate the result will be. Before weighing, dry the desized fabric in an oven until the weight is constant, and call it the dry weight, then
G(g／m2)=gxl0000/（Lxb）
G–slurry-free dry weight of sample per square meter (g/square meter); s –Slurry-free dry weight of the sample (g); L–sample length (cm); b–sample width (cm)
2. Calculation method When the sample area is very small and the weighing method is not accurate enough, you can calculate it based on the warp and weft yarn characteristics, warp and weft yarn density, and warp and weft yarn shrinkage obtained from the previous analysis. The formula is as follows:
9: Analyze the organization and color of the fabric Yarn matching
After making the above measurements on the cloth sample, the interweaving patterns of the warp and weft yarns in the fabric should be analyzed to obtain the organizational structure of the fabric. Here On this basis, the fabric’s machine drawing is correctly determined based on factors such as the raw materials, characteristics, and density of the fabric’s warp and weft yarns.
In the work of analyzing the structure of fabrics, our commonly used tools are cloth mirrors, analysis needles, scissors and colored paper, etc. The purpose of using colored paper is to have an appropriate background when analyzing fabrics , save your eyesight. When analyzing dark fabrics, you can use white paper as a background, and when analyzing light-colored fabrics, you can use black paper as a background.
Due to the wide variety of fabrics, raw materials, density, and yarn characteristics Numbers and other factors are different, so appropriate analysis methods should be selected so that the analysis work can get twice the result with half the effort.
Commonly used fabric tissue analysis methods include the following.
The yarn breaking analysis method is suitable for beginners. This method is applied to pile fabrics, terry fabrics, etc. Leno fabrics, multi-layer fabrics and fabrics with low yarn count, high density and complex structure
This method can be divided into group splitting method and There are two methods of splitting yarn.
(1) Group splitting method: For complex organizations or The group yarn splitting method is accurate and reliable for organizations with large colored yarn circulation. This method is now introduced.as follows.
a. Determine the system of yarn removal: When analyzing the fabric, the direction of yarn removal should first be determined in order to clearly see the interlacing state of warp and weft yarns. Therefore, it is advisable to disassemble the yarn system with higher density and use the gaps in the yarn system with lower density to clearly see the interweaving patterns of warp and weft yarns.
b. Determine the analysis surface of the fabric; which side of the fabric is analyzed is generally based on the principle of clearly seeing the organization of the fabric. For example: if it is a fabric with warp or weft weave, it is more convenient to analyze the reverse side of the fabric. If it is a surface scraped or milled fabric, you should first use scissors or a flame to remove part of the fluff on the surface of the fabric during analysis, and then perform tissue analysis.
c. Grouping of yarn tassels: First remove several yarns of one system on one side of the fabric sample, so that the yarns of another system of the fabric expose 10mm of yarn tassels, and then remove the yarns in the yarn tassels. Divide each number into a group, and cut the yarn tassels in odd-numbered groups such as 1, 3, 5… and the even-numbered groups such as 2, 4, 6… into two different lengths. In this way, when the disassembled yarn is placed in the yarn tassel, it can be clearly seen how it is interlaced with the odd and even groups of yarns.
If the design paper used to fill in the organization has eight small cells in the vertical and horizontal directions, which are exactly equal to the number of yarn tassels in each group, then each large cell can be regarded as a group and divided into The odd and even number groups correspond to the odd and even number groups divided by Shaying, In this way, the interweaving rules of the disassembled yarns in the yarn can be very conveniently recorded on the squares of the craft paper.
(2) Splitting yarn without groups method: After understanding the method of splitting yarn without groups, it is easy to understand the method of splitting yarn without groups. First, choose the analysis surface, the direction of yarn removal and theIt is the same as splitting the yarn into groups. This method does not need to group the yarn tassels. You only need to gently dial the yarn tassels into the yarn tassels and write down the pattern of interweaving warp and weft yarns on the craft paper.
2. Local analysis method. Some fabric surfaces have local patterns. The organization of the ground cloth is very simple. At this time, only analysis is needed.Don’t analyze the situation of the pattern and ground cloth; then according to the number of warp and weft threads of the pattern and the number of weave cycles of the ground cloth, you can calculate the number of warp and weft threads of a pattern cycle without having to draw each warp one by one. At the weft weave point, attention must be paid to the unification of the starting points of the ground weave and the flower weave.
3. Direct observation method Experienced craftsmen or fabric designers can use the direct observation method to directly observe the fabric by sight or using a cloth mirror, and fill in the observed interweaving patterns of warp and weft yarns into the squares of the craft paper one by one. You can fill in the interweaving status of several more warp and weft yarns in order to correctly find out the complete structure of the fabric. This method is simple and easy to use and is mainly used to analyze original weave fabrics with low single-layer density and large number of yarns. Simple small patterned fabric.
When analyzing the fabric weave, in addition to being meticulous and patient, you must also pay attention to the relationship between the weave of the cloth sample and the arrangement of colored yarns. For white fabrics, this problem does not exist during analysis. However, most fabrics have style effects. , not only reflected by the interweaving patterns of longitude and latitude, but also often The appearance effect is obtained by combining the weave with the colored yarn. Therefore, when analyzing the fabric (dyed fabric) in which the weave is matched with the weave, it is necessary to combine the weave cycle and the colored yarn arrangement cycle on the fabric’s tissue diagram. , it is necessary to mark the color and circulation rules of the yarn.
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