During the working process of the tenter setting machine, its temperature is the main factor affecting the quality of heat setting. During the operation, because the original wrinkles are eliminated after the fabric is heat-set, the surface smoothness is improved. The dimensional thermal stability and other wearing properties of the fabric are closely related to the heat setting temperature.
The setting time of the tenter setting machine is another main process condition for heat setting. After the fabric enters the heating zone, the time required for heating and setting can be divided into the following parts:
1. Heating time: the time required to heat the surface of the fabric to the setting temperature after the fabric enters the heating zone.
2. Heat penetration time: After the surface of the fabric reaches the setting temperature, the heat penetration time required to make the fibers inside and outside the fabric have the same setting temperature.
3. Molecular adjustment time: After the fabric reaches the setting temperature, the molecules in the fiber are adjusted according to the setting conditions.
4. Cooling time: The time required for the fabric to be cooled after the fabric leaves the drying room to fix the size of the fabric.
The setting time usually referred to by the stenter setting machine usually refers to the time required for the first three items, excluding the fourth item to a certain extent. If one item is regarded as a preheating effect, then the setting time only refers to the time required for the second and third items, that is, the time required for thermal penetration and molecular adjustment.
The time required for heating and heat penetration depends on the performance of the heat source, the weight of the fabric unit area, the thermal conductivity of the fiber and the moisture content of the fabric. The tension on the fabric during the heat setting process has a certain influence on the setting quality, including the dimensional thermal stability, strength and elongation at break of the fabric.
The warp dimensional thermal stability increases with the increase of warp overfeed during shaping, while the weft dimensional thermal stability decreases with the increase of the door width.
The average single-yarn tenacity of the fabric after setting is slightly higher than that of the unshaped fabric, and the change in the weft direction is more obvious than that in the warp direction.
The elongation at break of the fabric after setting, the weft direction decreases with the increase of the stretch degree, while the warp direction increases with the increase of the overfeed.
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