Calendering, is a process of fabric finishing, a finishing process that uses the physical plasticity of fibers under high pressure or high temperature to flatten or roll out patterns on the fabric surface to enhance the luster of the fabric.
According to the roll surface material, rolling pressure, temperature, different combination of soft and hard rolls and cloth dressing mode, different calendering effects can be obtained.
The upper roller is a metal roller with highly polished surface, which is also a heating roller. The middle roller is a nylon roller and the lower roller is a metal roller, which mainly acts as a supporting roller. During the production, the cloth passes through the upper roll (induction heating roll) and the middle roll (nylon roll). Under the pressure state, the induction heating roll and nylon roll form the rolling point, and the cloth passes through the rolling point to achieve the calendering effect.
The process temperature is from cold pressing to 160 ℃, the speed is 70m / min, and the pressure is 8 ~ 10kg.
Application: it is mainly used for fabric that requires calendering to have general luster, improve hand feeling (after calendering, the handl feeling will become soft and smooth), the smoothness of rolled cloth surface, the removal of paste flower on the fabric surface (the cloth surface looks like white watermark), the color change (the color will become lighter after rolling), and the previous process of coating finishing (the coating after calendering can increase the water pressure resistance of the fabric, and the glue surface is smoother, meanwhile glue saving) For example, 380t nylon (no gall proof) is popular in recent years.
In the middle is the induction heating roller, and the upper and lower is the nylon roller. When working, the cloth passes through the lower roller and the induction heating roller, and then passes between the heating roller and the upper roller, thus forming two rolling points, which is equivalent to that the fabric is rolled twice.
The process temperature is 120 ~ 160 ℃, 8 ~ 10kg pressure, 40m / min.
Application: It feels soft and thick, waxy and skin like,leather effect, such as Multi-F polyester Taffeta leather film calendering finishing.
It consists of two electromagnetic induction heating rollers, three cotton rollers and two upper and lower metal idlers. When working, the cloth is bypassed between the rollers to form five rolling points to achieve the effect of repeated calendering. Similar to the seven roll mill, there are five roll calender and the six roll mill which changes the bottom two rolls of the seven roll mill into a nylon roll. The working principle is basically the same.
The process temperature is 110 ~ 140 ℃, the pressure is 4 ~ 8kg, and the speed is 60m / min.
Application: mainly used for down proof finishing of down jacket inner liner, such as the most common 290t polyester Taffeta fabric.
Temperature, speed and pressure are the three elements of calender. The reason of unsatisfactory effect after rolling should be found from these three aspects.
1. The handle is hard, and the handle is too hard after finishing：It should be considered that the temperature, pressure and speed are too high and too slow. The handle after oil surface is too hard：It can be pressed by mirror cold. Of course, if the fabric is too hard before finishing, it is unlikely to become too soft after rolling.
2. If the gloss is too bright or too dark: the brightness is mainly determined by the temperature. Too bright, should lower the temperature, speed up the speed and reduce the pressure. Too dark, takes the opposite.
3. Edge difference and head tail difference: both sides should reduce the pressure, the middle light should increase the pressure (roller has crown); head tail difference: should be the temperature is not consistent, general temperature control in plus or minus 5 degrees.
4. Anti nap effect is poor: should slow down the speed and increase the temperature and pressure, or increase the number of calendering.
5. Wrinkling is a common problem in calendering. Both sides of crease printing should increase the tension of cloth feeding, and the middle wrinkle printing should reduce the tension of cloth feeding. The middle wrinkle mark also needs to check whether the lower cloth rack is clean. If the friction force is too large, it is easy to cause the cloth surface scratch. Generally, the cloth should be made into large packages before processing, so as to achieve the purpose of constant tension.
6. Calendering spot: Calendering spot is the most common defect, which is caused by the unclean roll surface (for example, there is thread end on the roll surface). The roller surface must be wiped frequently in production. Roller surface damage can also produce calendering spots(e.g. the concave pits caused by nylon roller pressing to hard objects).