A brief discussion on the use of sewing threads
The ancient ancestors evolved the sewing technology with one stitch and created various types of sewing threads; in clothing production, one stitch First-line and its continuous improvement of craftsmanship have created many brands. It goes without saying that thread plays an important role in clothing.
1. Classification of sewing thread varieties
Sewing threads include pure cotton, nylon, polyester-cotton, blended, polyester and rayon, etc., generally made of two strands, three strands, four strands, six strands It is made up of twisted single yarns, and the twisting direction can be divided into two types: s twist and z twist. Lockstitch sewing machines generally use z-twist thread, and good-quality s-twist thread can also be used on other sewing machines. Cotton sewing thread has good sewing performance, but it shrinks more than synthetic fiber thread during washing. Its strength, chemical resistance and abrasion resistance are also worse than synthetic fiber. High-quality mercerized cotton thread is expensive, so cotton sewing is rarely used nowadays. Wire. Short fiber polyester sewing thread has low cost, excellent stitching stability, durability and sewing properties, so it is suitable for all conventional garment sewing. The sutures used in overlock sewing machines are generally cotton threads. However, due to the high cost of cotton fiber, polyester-cotton threads are generally used instead.
The following is an introduction to the characteristics of various types of threads:
(1) High-strength polyester thread: currently one of the most conventional and widely used types of sewing threads on the market, characterized by luster Good, no elasticity, good color fastness, strong tensile strength. It is widely used in sewing PVC, thicker fabrics, and nylon leather products.
(2) Fishing net thread (transparent thread): Transparent thread is divided into nylon and polyester monofilament, which are also different in stretch, hardness, tension and use. It is often used for weaving, sewing trademarks, suit trouser legs, sewing transparent materials and various craft products.
(3) Pure cotton thread (polyester staple fiber thread): Polyester staple fiber thread is a widely used conventional thread with a few burrs on the surface, but has excellent breaking strength, gloss and wear resistance. inferior to other lines. It is used for thinner fabrics. The pure cotton thread is made of combed and singed natural cotton. It is specially produced for sewing pure cotton fabrics.
(4) Waxed rope thread (horse thread): Waxed rope thread is divided into two materials: nylon and polyester. The linear shape is better, and the pulling force is particularly strong. After being waxed, it becomes wax rope thread, which is often used for thick leather. Car sewing or hand sewing operations for thick products such as sofas, outdoor appliances, casual shoes, leather jackets, etc.
2. The relationship between sewing thread and sewing needle
(1) Choose the thickness of the suture
When choosing the thickness of the suture, you should first consider the thickness. Use of sewing thread. Specifically, consider the following aspects: ① The bobbin volume of a lockstitch sewing machine is limited. Using a thinner sewing thread can accommodate longer sewing threads, saving time on changing shuttles and achieving high work efficiency. ②Thin sewing thread is small in size and feels good during chain sewing. ③ Thin sewing threads take up very little space when sewing and are less likely to cause fabric deformation and sewing wrinkles. ④For fine sewing thread, use a small number needle to avoid needle holes in the fabric. ⑤Thin sewing thread can also reduce prominent seam marks, making them sink into the inner layer of the fabric surface and reduce the impact of wear.
In the sewing process, to form correct stitches, it is necessary to ensure that the specifications of the needle, suture, and sewing material match. In addition, you need to pay attention to the following two points:
First, the twist of the suture should also be considered during the sewing process. The purpose of twisting the suture is to increase the strength and elasticity, but if the twist is too high, it will cause The suture roll affects the normal formation of the thread loop. Under normal circumstances, take a 1-meter-long suture and grasp the two ends of the thread to bring it close. The number of natural twisting turns of the two strands of thread should not be greater than 6, otherwise skipped stitches will easily occur.
Second, when sewing, if the sewing material is thin and soft, a fine needle must be used. At the same time, the lifting amount of the needle should be increased, because the friction between the suture and the sewing material is small. If the lifting distance remains unchanged, , which relatively reduces the width of the upper thread loop, affects normal hooking, and may cause stitch skipping. If it is a rough fabric, the opposite is true.
(2) Selection of machine needle
When selecting a good suture, the needle is also an important sewing machine component that should be considered in sewing. The working nature of the machine determines the selection of machine needles. Machines of different natures need to be equipped with different models and specifications of machine needles. For example, a lockstitch sewing machine uses a 96?1 type or an 88?1 type needle; an overlock sewing machine uses an 18?1 type machine. Needle etc.
Regardless of the type of machine, the needle size must be selected according to the nature and thickness of the sewing material during the sewing process. Generally speaking, the needle points of machine needles used for textiles and knitwear are ground into a conical shape. When sewing leather and similar sewing materials, special-shaped needle points are used, such as spear points, diamond points, reverse twist points, etc., for the purpose of sewing leather and similar sewing materials. It increases the needle strength and achieves good sewing results.
3. Accounting and cost of thread usage
There is such a problem in most garment factories: all kinds of sewing threads pile up, whether they are newly developed or in stock. , which is a waste of cost. In order to avoid excessive waste of thread in the production process, the accounting method and significance of thread usage are now introduced: First, for the needs of clothing cost accounting: thread usage is part of the total cost of clothing production, and only Only with a more accurate calculation can we conduct a comprehensive cost accounting of the product. Second, it is beneficial to planning and management: knowing the amount of thread used is beneficial to procurement and material preparation, and provides necessary conditions for on-time delivery and quality assurance of garments. There are two main ways to calculate the line amount: the ratio method and the formula calculation method.
(1) Use the ratio method to estimate the amount of thread used
The amount of sewing thread used is determined by many factors, such as the thickness of the fabric, the softness and hardness of the fabric, the type of stitches, The density of the stitches, the thickness of the thread, the tension of the thread and the pressure of the machine's presser foot, etc. These factors change frequently, so it is not easy to calculate the amount of thread usage very accurately. At present, the ratio method is generally used to estimate the amount of wire consumption.
The so-called "ratio method" is to summarize based on experiments the ratio of the consumption of sewing thread (length m) to the length of sewn fabric (m) under various conditions when sewing a certain length of fabric e= l/c, this e is called the suture consumption ratio. With this ratio e, you can use it to estimate the practical thread amount.
In the formula l=c?e, l is the amount of thread used (m); c is the sewing length (m), and e is the thread consumption ratio. To estimate the amount of line used by the ratio method, the ratio e must first be found through experiments. There are two specific experimental methods, namely the suture fixed length method and the suture fixed length method.
①Sewing length fixing method
First make preparations for the experiment, that is, choose a sewing machine with good performance, adjust each part according to the actual required process conditions, and prepare the regulations of fabric and sewing thread, and then measure a certain length of sewing thread (such as 1m), leaving a margin of 0.5m at the front end when measuring. Mark the measured section of thread with a clear color, and then wind it onto the spool. After winding, use this section of sewing thread to actually sew on the selected fabric according to the actual operation requirements until all the colored sections are sewn. until finished. Finally, remove the sewn fabric and measure the actual sewing length of the colored line segment, so that the amount of thread used per meter of stitch can be calculated, which is the ratio e. e=The length of the colored line segment (m)/the stitch length of the colored line segment (m).
②Sewing length fixing method
The preparation for the experiment is the same as the above method, and then directly use the specified sewing thread and fabric to sew according to the actual operation requirements, and sew to 0.5 m or above. After sewing, measure a certain length (more than 20cm) in the middle of the stitch, and cut this stitch with scissors. Finally, remove the sewing thread from this stitch (be careful not to break the thread), measure the actual length of the thread, and then calculate the amount of thread used per meter of stitch, that is, the ratio e. e=actual length of removed thread (m)/measured stitch length (m).
For flat stitches, since the upper and lower thread structures of the stitches are the same, if the same kind of sewing thread is used, you can only experiment with the amount of upper thread, and the total thread amount is twice the amount of upper thread. Since the upper and lower thread structures of other stitches are different, experiments must be conducted separately to obtain the thread consumption ratio of the upper thread and the lower thread. For example, if flat stitch is used, the stitch density is 8 stitches/2cm, the fabric thickness is 1mm, the sewing thread is 9.8tex?3 (60 inches/3), and the sewing length of the entire garment is 6.5m, the estimated garment length Amount of thread used. Checking the clothing technology book, we can see that e=2.73, so l=e?c=2.73?6.5=17.745m.
(2) Use the formula calculation method to calculate the thread amount
This method is to calculate the thread amount of a unit stitch based on the shape characteristics of various stitches. , and then calculate the formula for the actual thread amount used for sewing a certain length of fabric.
The calculation of the formula can be divided into three steps: 1. According to the shape characteristics of the stitch, idealize the geometric shape of the stitch, assuming it to be a regular geometric shape, for example, each of the flat stitches The sewing circle can assume a rectangular or oval shape. 2. Calculate the line amount of the unit trace based on the assumed geometric shape. The amount of wire used for each unit stitch includes the amount of wire used for one coil and the amount where each coil connects to adjacent coils. 3. Based on the thread quantity formula of the unit stitch and the stitch density and other conditions, the thread quantity formula required for calculating the one-meter-long stitch suitable for practical applications is deduced.
Taking flat stitch (301) as an example, we can get: l1=2+0.2dt+0.26d/(nm*?)1/2;l2=1.57+0.16dt+0.36d/ (nm *?)1/2
In the above formula, when l1? flat stitch is assumed to be rectangular, the calculation formula of the sewing thread length (m) required to sew one meter of fabric. l2? Calculation formula for the sewing thread length (m) required to sew one meter of fabric when the flat stitch is assumed to be oval. d? Stitch density (number of linear variable units/2cm). t? Thickness of fabric (mm). nm? Metric count of sewing thread. ? is the specific gravity of sewing thread, pure cotton thread ? is about 0.8 ~ 0.9g/cm3, polyester cotton thread ? is about 0.85 ~ 0.95g/cm3.
For example, it is known that flat stitch is used for sewing, the stitch density is d=9, the fabric thickness is t=1.2mm, the sewing thread is 60s/3 polyester-cotton thread, and the total sewing length is 6.5m. Calculate its wire usage.
Calculation: Assuming the trace shape is rectangular, then nm=1.693ne=1.693603 =33.86
l1=2+0.2?9?1.2+0.26*9/(33.86*0.9 )1/2 =4.58m, the total suture length =l1?6.5=4.58?6.5=29.77m.
Assuming the stitch shape is elliptical, then l2=1.57+0.16dt+0.36d/(nm*?)1/2 =1.57+0.16?9?1.2+ 0.36*9/(33.86* 0.9)1/2=3.88m, the total suture length=l2?66.5=25.22m.
In fact, ordinary domestic threads are about 3 yuan each, while imported threads are about 20 yuan each, dozens of times more than domestic threads, but they are superior in terms of color fastness, shrinkage, etc. Domestic line. Clothes with a retail price of thousands of yuan must be perfect in every aspect, and pay more attention to quality, regardless of the price of the thread, so that you won't lose a big due to a small gain.
In the process of making clothes, choosing sewing needles and threads seems to be a very simple problem, but in fact it is not the case. It must not only meet the technical requirements, but also take into account the aesthetic requirements. Only by considering the matching of the thread and the sewing material, the color matching of the sewing thread and the sewing material, and the selection of the fineness of the sewing thread can we achieve a more perfect effect. ;