Significance and Explanation of Yarn Coefficient of Friction Measurement

The main problems of knitting yarn at present

The quality and performance of knitted fabrics depend on the properties of knitted raw materials, the structure and specifications of knitted fabrics, dyeing and finishing and other factors. Among them, the performance of knitted raw materials is the main factor affecting the properties of knitted fabrics. The use of knitted fabrics is different, and the raw materials used are also different. At present, most of the knitted fabrics for underwear use cotton yarn; the raw materials of hosiery products are cotton yarn, wool and chemical fiber; wool sweaters are mainly made of wool, acrylic, acrylic blended yarn, etc.; the main raw materials of knitted outerwear are polyester, nylon, acrylic and blended Yarn and new textile materials (such as tencel fiber, differential fiber, etc.); raw materials for special industries are mainly glass fiber, metal wire, aramid fiber, etc. The components of the raw material can be pure spun yarn containing only one kind of fiber or blended yarn of more than two kinds of fibers; (such as color yarn, slub yarn, knot yarn, core-spun yarn, etc.). In addition, the emergence of new raw materials such as chemical fiber special-shaped fibers, composite fibers, especially ultra-fine denier fibers, has opened up new ways for knitting yarns.

 In the process of forming a knitted fabric on a knitting machine, the yarn is subjected to complex mechanical actions, such as stretching, bending, twisting, friction, etc. In order to ensure the normal production and product quality, knitting yarns should meet different requirements:

1. The yarn should have certain strength and extensibility

2. The yarn should have good softness

3. The thread should have a certain twist

4. The linear density of the yarn should be uniform and the yarn defect should be less

5. The yarn should have good hygroscopicity

6. The yarn should have a good finish and a small coefficient of friction

The knitting yarn should be free of impurities and oil stains as much as possible, and should be very smooth. Unsmooth yarns cause severe wear and tear to parts, which are easy to damage, and there are many flying flowers in the workshop, which not only affects the health of workers, but also affects the productivity of the knitting machine and the quality of the fabric.

In addition, during the knitting process, the yarn is also in frictional contact with a variety of mechanical parts to make relative sliding, so that the yarn is subjected to a certain resistance, thereby generating yarn tension. Therefore, yarns with rough surfaces or yarns with an excessive coefficient of friction will generate high yarn tension when passing through the loop-forming machine, which will affect the uniformity of yarn tension and cause uneven coil structure. In order to reduce the friction coefficient of the yarn, the surface of the yarn can be treated with antistatic agents and lubricating agents or waxes.

The yarn gains tension due to friction as it slides over other surfaces. In practical applications, the yarn passes through several sinkers and several hooks, and the yarn tension increases significantly when the coefficient of friction increases. The increase in tension depends not only on the coefficient of friction, but also on the sum of the wrapping angles of the yarn guides, needles and sinkers when the yarn slides.

In the process of textile processing, there are often relative motions between yarns and yarns, and between yarns and machine parts, resulting in friction between yarns or between yarns and other materials. Sufficient friction between yarns is a necessary condition for good dimensional stability of fabrics, but excessive friction will cause difficulty in beating-up during the weaving process and affect the quality of the fabric. The size of the coefficient of friction also directly affects the appearance and style of the fabric. For example, the friction between the yarns determines the interlacing resistance of the fabric to a certain extent. If the interlacing resistance is too large, the fabric will generally feel hard and rough; Distortion easily occurs. In addition, the frictional resistance between the yarns plays a decisive role in the difficulty of shear deformation of the fabric, and the round shape of the full chest and back requires the fabric to have good shear deformation ability. Therefore, the determination of the yarn friction coefficient is of great significance.

The XHX-24 Yarn Friction Tester ASTM D 3108 launched by our company is used to measure the friction characteristics of the yarn, which is suitable for the determination of the dynamic friction coefficient of chemical fiber filament and other material yarns, and can also be used for textiles such as top rollers. The friction coefficient measurement of equipment is an indispensable test instrument for evaluating the friction coefficient of filaments and textile equipment.

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