1. Crease Mark
If the sanding products are not processed properly, regular or irregular warp and weft crease marks can be produced on the fabric surface, which will seriously affect the appearance quality and sanding effect of the products. Causes of crease marks and measures taken mainly include:
- The fabric is piled up in the folded (or wrinkled) state for a long time, and is pressed by its own gravity, resulting in irregular and uneven warp and weft crease marks on the fabric surface. Therefore, the storage mode of fabrics should be changed to roll (stack) storage in large packages, which can effectively prevent crease printing.
- In the pretreatment of sanding, the temperature of fabric doffing is too high, resulting in relatively permanent wrinkle, which is mainly for chemical fiber and its blended fabrics. This kind of crease is difficult to remove and often needs to be shaped once. For cotton-type or lightly wrinkled fabrics, spray wetting and equipment drying can be arranged in front of the sanding machine to solve the problem.
- In the fabric pretreatment and dyeing process, wrinkles and stripes can be caused due to process, equipment and operation problems, or due to improper sewing head. Therefore, in order to overcome the wrinkle defect of sanded products, all working procedures should be strictly controlled.Usually, in the process of sanding, the original weft crease marks can be removed, but the warp crease marks cannot be removed, leaving traces of uneven fluff and different shades on the fabric surface.
2. White Core
The white core is produced on the surface of the ground wool fabric, mainly because there are neps left on the grey fabric, which can be covered after dyeing. However, once the wool is ground, the neps are removed, leaving white spots, even causing small holes, which will affect the product quality. Therefore, for the original grey fabric, it is required to reduce neps as much as possible, or pick neps to the opposite side of the fabric; You can also use sanding before dyeing and dyeing after grinding to control white core defects.
(1) The uneven surface of sanding roller or improper coating of sand skin causes uneven abrasive surface and stripes.
(2) Sanding roller is first used to grind narrow fabric, and then to grind wide fabric. Because the surface wear of sanding roller is different, it is easy to cause a medium difference between grinding surface and grinding edge, resulting in stripes on both sides.
(1) emery skin should be flat and tightly rolled with the roller, the guide should be straight, the surface should be flat, and it should be kept clean without dirt.
(2) emery skin should be wrapped in oblique and strip shape, and both ends should be rolled firmly.
(3) Check the equipment regularly to ensure that the guide roller is flat and the sand skin is in good bonding condition with the guide roller.
After sanding, the color of the fabric will change. Generally, it becomes shallow, resulting in a certain color difference between the sanded surface and the unmashed surface, which is mainly due to the different reflection of light by the fluff on the surface of the sanded fabric. Therefore, the color difference after sanding should be fully considered when dyeing, and there should be a slight allowance for the dyeing depth. In addition, the penetration rate is the key, and the requirements for penetration dyeing are higher than those of ordinary dyed fabrics.
Experiments show that different types of dyes have different effects on the color difference of fabrics before and after sanding because of their different molecular structure, dyeing performance and affinity. For example, light-colored fabrics with vat dyes and reactive dyes have small color difference before and after sanding, which is suitable for dyeing first and then grinding; for medium and dark-colored fabrics, the color difference before and after sanding is large, which is suitable for grinding first and then dyeing, and can also achieve the best effect of velvet, fullness and uniform dyeing.
5. Poor Sanding Effect
Semi-finished products have hard hand feel, poor cloth surface penetration effect, low tension, fast speed, long old use time of sand skin, unstable DC motor speed and wet cloth surface.
Notify the pretreatment to repair or apply softener, tighten the tension of chain shaft, slow down, increase pressure, change new sandpaper and fully dry the cloth surface.