What problems do pre-shrinking in fabric usually encounter?

The pre-shrinking problems that are easy to appear are scale spots, warp wrinkles, wrinkles, weft skew, wet cloth, insufficient shrinkage, narrow door width, etc.

1. Fish scale spots. It is caused by partial aging of the rubber blanket and uneven fabric shrinkage. Grind or replace the defective and aging rubber or felt.

Warp folds. It is caused by excessive warp tension when the fabric before shrinking has wrinkles or when the fabric enters the shrinking machine. In the pre-process, pay attention to prevent warp wrinkles, that is, relax the stretcher during pre-shrinking, reduce warp tension, and solve the warp wrinkle problem.

2. Wrinkle rolling. Too small tension in the cloth feed, too loose cloth surface, unequal pressure on the left and right sides of the cloth roll, too loose edges or uneven tightness on both sides of the grey cloth can cause wrinkles. Adjustable cloth stretcher to increase cloth feeding tension, adjust cloth feeding roller to maintain uniform pressure on both sides.

3. Weft skew. Causes include incorrect cloth feed position, uneven cloth guide roller, uneven pressure on both sides of the cloth roller, etc. When processing, the position of cloth feeding should be adjusted to ensure that the cloth guide roller is straight and the pressure should be adjusted to make the pressure at both ends of the cloth feeding roller uniform.

4. The cloth falls wet. Because the fabric is excessively wet during processing. Therefore, in the pre-shrinking process, the spray volume and running speed should be controlled well, and the speed can be reduced so that the falling cloth can be fully dried.

5. Insufficient shrinkage. The pre-shrinking effect is not good and the dimensional stability is poor. This is caused by the position of the pressure roller being too high, the temperature of the pressure roller being too low, the pressure on the cloth roller is not enough, and the tension of the cloth in and out is too high. The position of the pressure-bearing roller can be appropriately lowered, the spray wet can be controlled, the vapor pressure of the pressure-bearing roller can be increased, the pressure of the cloth roller can be increased, and the tension of cloth in and out can be reduced.

6. The door is narrow. The pre-shrinking front door width is insufficient due to the previous process, or the cloth feeding tension is too large during the pre-shrinking, which causes the fabric to narrow the door width after pre-shrinking. In the previous processing procedures, it is necessary to strictly operate according to the process to ensure that the width of the incoming cloth meets the requirements; at the same time, during the pre-shrinking process, attention should be paid to appropriately reducing the tension of the cloth.