[High-strength wire]What is high-strength wire and why should it be stretched?
What is high-strength wire
High-strength thread is a kind of sewing thread. The thread produced has certain tensile force, strong tensile force, luster, high temperature resistance and high speed. It is mainly suitable for leather sewing, such as shoe industry and bag industry. , sofa industry, etc. High-strength thread is the most common leather sewing thread.
Composition of high-strength threads
High-strength threads are suitable for sewing various garment materials, and have both functional and decorative functions. The quality of high strength not only affects the sewing effect and processing cost, but also affects the appearance quality of the finished product. Therefore, the general concept of high-strength thread formation, twist, the relationship between temperature resistance and strength, suture classification, characteristics and main uses, and selection of high-strength threads are introduced to facilitate enterprises to formulate standards for relevant tests. Determining the general concept of high-strength thread formation
Carding (carding)—yarns spun with only one end carded.
Combing—yarns in which both ends of the fibers are combed with a comber, resulting in fewer impurities and smoother fibers.
Blend—a yarn in which two or more fibers of different properties are mixed together.
Single yarn – directly formed on the spinning frame, it will spread out once untwisted, referred to as yarn.
Strands—two or more yarns twisted together, referred to as threads.
Sewing thread——A general term for the thread used for sewing garments and other sewn products.
New type of spinning—different from traditional ring spinning, one end is free end, such as open-end spinning, friction spinning, etc. Yarns are tangled together without twist.
Yarn count — an index used to indicate the fineness of yarn, mainly including inch count, metric count, special count, and denier.
High-strength wiretwist
Definition: Twisting through the fiber structure of the wire, resulting in a relative angle between the cross-sections of the wire Displacement, which changes the structure of the wire by tilting the straight fibers to the axis. Twisting can make the thread have certain physical and mechanical properties such as strength, elasticity, elongation, luster, hand feel, etc. It is expressed by the number of twists per unit length, usually the number of twists per inch (TPI) or the number of twists per meter (TPM) .
Twist: Rotate 360 degrees around the axis as a twist.
Twist direction (S or Z direction): when the sliver is vertical, the inclination direction of the helix formed by rotating around the axis. The inclined direction of the S twist direction is the same as the middle part of the letter S, that is, the right-hand direction or the clockwise direction. The inclined direction of the Z twist direction is the same as the middle of the letter Z, that is, the left-handed direction or the counterclockwise direction.
The relationship between twist and strength: The twist of the thread is proportional to the strength, but after a certain twist, the strength decreases. If the twist is too large, the twist angle will increase, the luster of the thread will be poor and the hand feeling will be poor; if the twist is too small, hairiness will occur and the hand will be loose. This is because the twist increases, the frictional resistance between fibers increases, and the strength of the thread increases. However, as the twist increases, the axial component force of the sliver becomes smaller, and the internal and external fiber stress is unevenly distributed, resulting in inconsistent fiber breakage.
In short, the breaking performance, strength and twist of the thread are closely related. The twist and twist direction are determined according to the needs of the finished product and post-processing, generally the Z twist direction.
Classification of high-strength thread
According to raw materials, it can be divided into natural fiber high-strength thread, synthetic fiber sewing thread and mixed sewing thread Three categories.
1. Natural fiber high-strength yarn
Cotton high-strength yarn——using cotton fiber as raw material, refining, bleaching and sizing , waxing and other links made of sewing thread. Cotton high-strength thread can be divided into no light (or soft line), silk light and wax light. Cotton high-strength thread has high strength and good heat resistance, suitable for high-speed sewing and durable pressing. Mainly used for sewing cotton fabrics, leather and high temperature ironing clothes, but the disadvantage is poor elasticity and wear resistance.
Silk thread—a filament thread or silk thread made of natural silk, with excellent luster, and its strength, elasticity and wear resistance are better than cotton thread. It is suitable for sewing all kinds of silk garments, high-grade woolen garments, fur and leather garments, etc.
2. Synthetic fiber high-strength yarn
Polyester high-strength yarn—made of polyester filament or staple fiber, with High strength, good elasticity, wear resistance, low shrinkage, good chemical stability. However, the melting point is low, the high speed is easy to melt, the needle eye is blocked, and the thread is easy to break. Pay attention to the selection of the needle. Mainly used for denim, sportswear, leather products, wool and military uniforms, etc., it is currently the most used and popular high-strength thread.
Nylon high-strength thread — made of pure nylon multifilament, divided into filament thread, short fiber thread and elastic deformation thread. At present, filament thread is commonly used, which has large elongation and good elasticity, and its tensile length at the moment of breaking is three times greater than that of cotton thread of the same specification. For the sewing of chemical fiber, woolen, leather and elastic garments. The biggest advantage of nylon sewing thread is its transparency. Because the thread is transparent and has good color, it reduces the difficulty of sewing and wiring, and has a broad development prospect. However, it is limited to the fact that the rigidity of the transparent thread currently on the market is too high, the strength is too low, the stitches are easy to float on the surface of the fabric, and it is not resistant to high temperature, so the sewing speed cannot be too high. At present, this type of thread is mainly used for decals, cutting edges and other parts that are not easily stressed.
Vylon high-strength thread—made of vinylon fiber, with high strength and stable stitch, mainly used for sewing thick canvas, furniture cloth, labor protection supplies, etc.
Acrylic high-strength thread – made of acrylic fiber, low twist, bright dyeing, mainly used for decoration and embroidery.
3. Hybrid high-strength thread
Polyester-cotton high-strength thread — 65% polyester, 35% cotton It is blended and has the advantages of polyester and cotton. It has high strength, wear resistance, heat resistance and good shrinkage rate. It is mainly used for high-speed sewing of cotton, polyester-cotton and other garments.
Core-spun high-strength thread—the filament is the core, and it is made of natural fibers. The strength depends on the core thread, and the wear resistance and heat resistance depend on the outer yarn. .
High-strength threadselection
Under the specified conditions, the high-strength thread forms a good stitch while maintaining certain mechanical properties. Ability, called sewability, is a comprehensive indicator for assessing the quality of sutures. According to the material, thickness, structure, color, sewing style, sewing equipment or means of the sewing material, select the type and specification of sutures and needles. Generally, the following principles can be followed:
1. Coordinated with the characteristics of the fabric
It can ensure the uniformity of shrinkage rate, heat resistance, abrasion resistance, durability, etc., avoiding the excessive difference between threads and fabrics. Shrink. Generally, thin threads are used for soft and thin materials with small needles, and thick threads are used for hard and thick materials, which are equipped with large needles.
2. Coordinate with sewing equipment
The lockstitch machine uses left-hand thread, which can be twisted during sewing to keep the seam Line strength.
3. Coordinate with the stitch form
The bag (interlock) sewing machine uses fine cotton thread, and the sewing material is not easy to deform and Wrinkle, and make chain stitch beautiful and comfortable. Double stitches should use sutures with good extensibility. The crotch seam and shoulder seam should use firm stitching. Buttonhole stitches should be durable stitches.
4. Coordinate with the type of clothing
For special-purpose clothing, such as elastic clothing, elastic nylon thread is required, fire suits High-strength wires with heat-resistant, flame-retardant and waterproof treatments applied.
