The purpose and method of heat setting: Due to the high elastic recovery rate of polyester fibers and the difficulty in eliminating stress, there is a large amount of twist added during spinning, resulting in a significant anti twist force that can only disappear over a long period of time.
By steaming the yarn, the anti twist force of the yarn quickly disappears, stabilizing the twist of the yarn to prevent a large number of yarn tangles and weft shrinkage defects during the weaving process. The yarn heat setting process is generally only used for the production of "f polyester/cotton fabric". The theme of yarn heat setting is used, which illustrates that in the production of polyester/cotton fabrics, not only the weft yarn, but sometimes the warp yarn tube also needs to undergo heat setting. To prevent the formation of "small braids" during the process of monopoly.
However, in most factories producing polyester/cotton fabrics, only the weft yarns are heat set because the warp yarns are mostly under tension during the production process, and there are fewer opportunities for them to form "braids". Moreover, during the drying process of sizing, the warp yarns actually undergo a heat and moisture setting.
The equipment used for heat setting is a setting pot wrapped with insulation material, which can be divided into two types. One is equipped with vacuum equipment, and the other is not equipped with vacuum equipment. The shaping effect of the two models is basically the same. However, first evacuate, steam or hot air can easily penetrate the inner yarn layer, reducing the difference in shaping effect between the inner and outer yarn layers, and also reducing the yellow white difference caused by yarn shaping.