Introduction to Spandex finishing
Spandex warping is a specialized warping process designed for the characteristics of spandex elastic yarns. The core is to wind a certain number of spandex yarns parallel onto the warp axis under the premise of ensuring uniform yarn tension and no stretching deformation, providing qualified warp yarn raw materials for subsequent warp knitting, weft knitting or weaving processes.
Spandex yarn features high elasticity, low modulus and easy shrinkage. Conventional warping processes can easily lead to excessive stretching and uneven tension of the yarn, which in turn causes elastic deviation of the fabric and uneven fabric surface. Therefore, spandex warping has extremely high requirements for equipment and process control.
I. Core Process Requirements
Precise tension control
This is the key to spandex warping. Spandex yarn cannot withstand excessive tension; otherwise, it will undergo permanent deformation and lose its elasticity. If the tension is too small, it will lead to loose winding and disordered yarn arrangement.
Usually, segmented tensioners are adopted, combined with elastic tension compensation devices, to control the tension of a single yarn within an extremely low and uniform range. At the same time, the tension parameters are adjusted according to the fineness of the yarn (such as 20D, 40D, 70D).
Anti-adhesion treatment
The surface of spandex yarn is smooth. If it is wound too tightly, interlayer adhesion is likely to occur. When it is unwound later, there will be broken ends or tension fluctuations. The process will adopt the intermittent winding method or apply a small amount of special anti-sticking agent on the surface of the yarn. The equipment is equipped with anti-sticking slot cylinders and the winding Angle is optimized.
Constant line speed winding
During the warping process, maintain a constant winding line speed to avoid an increase in the tension of the outer yarn due to an increase in the diameter of the warp axis. Generally, a variable frequency speed regulation system is adopted to monitor the diameter of the shaft in real time and adjust the rotational speed.
The yarns are evenly arranged.
Through high-precision reed separators and yarn guides, it is ensured that the spandex yarns are arranged in parallel and at consistent intervals, preventing the occurrence of yarn splitting and overlapping, and ensuring the surface of the warp shaft is flat.
Ii. Common Types of Warping Equipment
Slitting warping machine (suitable for small batches and multiple varieties)
Divide the spandex yarn into several strips and wind them one by one onto the warp axis. The advantages are that the pattern changes are flexible and it is suitable for the production of small samples of elastic fabrics. The disadvantages are that the production efficiency is relatively low and the tension uniformity is slightly inferior to that of batch warping machines.
Batch warping machine (suitable for large quantities and high requirements)
At present, the mainstream equipment for spandex warping adopts collective barrel changing and single yarn tension control mode, which can handle hundreds of yarns simultaneously.
Key configurations include:
Elastic tensioner: Adapted to the low tension requirements of spandex;
Electronic yarn cleaner: Detects yarn defects and automatically cuts them.
Computer control system: Set parameters such as tension, speed and length, and monitor the warping quality in real time.
Spandex Special stretching and warping combined Machine (for high-elasticity fabrics)
It integrates drawing and warping functions and is suitable for warping covered yarns of spandex, cotton yarn, polyester yarn, etc. The stretch ratio of spandex can be precisely controlled to meet the elastic requirements of products such as elastic fabric and elastic socks.
Iii. Application Scenarios
Spandex warped warp shafts are mainly used for the production of various elastic fabrics:
Warp knitting field: elastic underwear fabric, sportswear fabric, swimwear fabric, elastic mesh fabric;
Weft knitting field: elastic knitted fabrics, spandex covered yarn knitted fabrics;
Weaving field: stretch denim, stretch casual pants fabric, stretch shirt fabric.
Iv. Common Process Problems and Solutions
Uneven yarn tension: Check if the tensioner is worn, replace the elastic tension compensation device, and unify the yarn batch number and bobbin size.
Axial adhesion: Reduce winding pressure, increase interlayer gap, and use special anti-adhesion agents.
High yarn breakage rate: Check if there are burrs in the yarn guide channel, reduce the warping speed, and optimize the tension parameters.
