The reason for the size error of customized seamless leggings is roughly: due to the lack of workers’ awareness of quality, the operator’s negligent management of the machine, the uneven quality of raw materials, the processing environment and the degree of processing quantity.
According to the customer’s requirements for the size of customized seamless leggings, the appropriate caliber is selected on the seamless circular knitting machine, and then the parameters such as line speed, tension and suction are adjusted on the equipment according to the requirements of the finished clothing, so as to achieve the required size.
The reason for the size error of customized seamless leggings
Due to the special nature of custom seamless leggings, there is no way to accurately reach the size of the finished product through drawing board cutting. Therefore, seamless underwear has a certain size error range, but the actual manufacturer often exceeds the allowed error range. The main reasons are as follows:
1. Reasons for weaving and dyeing
1.1 Human Factors
a. Weaving workshop staff, lack of systematic training, lack of quality awareness of size issues, ignore the quality inspection of seamless leggings;
b. Dyeing technicians and operators have insufficient knowledge of the allocation ratio of slurry, and tend to ignore the influence of pre-dyeing process, dyeing temperature, dyeing time and dyeing pH value on slurry.
1.2 Machinery and Equipment
a. The selection of equipment caliber is not reasonable;
b. Inconsistent standards between the same caliber equipment, such as tension (poor tension control or inaccurate tensiometer resulting in poor suction control of the equipment), line speed (line speed is out of control, resulting in a change in coil length), etc., resulting in a difference in the size of seamless leggings;
c. Because the yarn suction pipe is not smooth or the pipe travel is different, the yarn suction amount of each equipment is not uniform, affecting the stability of the size;
d. Preshrinking and dyeing process parameters are inconsistent, resulting in size instability;
e. The capacity of the dyeing equipment is different, the size of the small tank dyeing will be smaller, and the size of the large tank dyeing will be slightly larger.
1.3 Raw Materials
a. There are quality differences in the selection of raw yarns. For example, the raw materials provided by the factory are unstable, the tension and elasticity of the inner and outer layers are inconsistent, and the elasticity of the yarn is easily damaged. The batch number of raw materials is unstable, and the batch number may be changed halfway, resulting in some seamless leggings products not reaching the standard size.
b. The improper selection of dyes and auxilaries, especially the improper selection of oxidants, reducing agents and pH, such as the concentration and dosage of hydrogen peroxide during oxygen bleaching, pH value, alkalinity during reduction cleaning or peeling, and the amount of insurance powder, will affect the size error.
1.4 Improper processing methods
Before putting into sewing production, the technician did not accurately test the size, or did not test the size according to the large-scale dyeing process of the printing and dyeing workshop. The workshop staff cut the semi-finished products that have been dyed irregular, which leads to large size errors. Because seamless leggings are flexible, the ironing temperature may be too high in the final ironing stage, resulting in a change in size.
1.5 Environment
The instability of temperature and humidity in the workshop will lead to the instability of seamless equipment, resulting in size fluctuations; The negative pressure in the workshop causes uneven suction, which makes the seamless leggings uneven in density.
Prevention and improvement measures
1. The selection of good materials, especially the quality of core-spun yarn, requires stable batch difference, and the density, tension and elasticity of the inner layer, middle layer and outer layer should be consistent.
2. After selecting the seamless garment making machine, be sure to ensure that the number of product rows of the same caliber and size are consistent. It is important to make sure that the product of the number of parallel lines is the same. This is the first condition to ensure the dimensional stability of the product.
3. Keep the roll length consistent, line speed consistent, yarn feeding tension consistent. Require regular inspection of coil length, wire speed and wire tension. When the running status of the device changes, you must measure the above parameters in time. If any changes are found, adjust them in time.
4. Strictly control suction and record machine size. If the size of the machine changes, the cause should be found immediately and adjusted.
5. Control the temperature and humidity of the weaving workshop. The temperature and humidity of the workshop should be recorded regularly to keep the temperature change within the allowable range. If there is a large fluctuation, it should be adjusted in time.
6. While controlling the size of the machine, it is best to have a technician to spot check and test the size every day.
Dye improvement and preventive measures
1. The main purpose of steaming is to stabilize the size. The steaming temperature is generally higher than the dyeing temperature, and it is necessary to maintain a stable temperature.
2. Select the dyeing equipment and try to dye on the same type of dyeing equipment.
3. The effect of PH value: Strictly control the PH value (between 4 and 10) during the dyeing process to maintain the minimum damage of acid and base on elastic fibers such as spandex.
4. The effect of oxidizer: Control the oxygen bleaching process of cotton and spandex products, such as the amount of hydrogen peroxide, pH value, oxygen bleaching temperature and time.
5. Reducing agent effect: Use reducing powder after product repair and stripping, and wash dye with disperse dye. Powder is easy to cause elastic damage to elastic fibers and spandex. Therefore, the use of reducing agents should be avoided as much as possible, and the treatment process during cleaning and peeling of reducing agents should be controlled.
6. Water quality: There is still iron or iron ions in the water. If the levels are too high, spandex will be damaged. If the iron content is too high, water treatment should be carried out before pretreatment and dyeing.
CONCLUSION
In seamless underwear processing, dimensional instability is a common problem and the most difficult to control. There are two main countermeasures: First, strengthen management. The second is to control the weaving, preforming and dyeing processes.
