Analysis of the curling and wrinkling problem of composite packaging bags

In the actual production process of composite packaging bags, there are often faults due to mechanical reasons or other factors, such as: generation of bubbles, low compound fastness, curling, wrinkling, stretching or shrinking. The curling and wrinkling of composite packaging bags may seriously affect the production of customers and cause significant losses to customers.

Today, the professional packaging manufacturer Lucky Time Pack will combine its own experience in producing composite packaging bags to explain how to avoid the occurrence of curling and wrinkling.

The occurrence of curling and wrinkling is related to the quality of its own material

If the difference in the tightness of the two ends of the film roll is large, the amplitude of the film up and down, left and right is also relatively large after starting the machine, which may cause wrinkling and curling, because the material when entering between the hot steel roller and the hot-pressed rubber roller, it cannot be in a horizontal state with the hot-pressed rubber roller, and cannot be squeezed smoothly, causing the composite packaging bags to wrinkle and appear twill, resulting in product scrapping.

When the composite material of packaging bags is PE or CPP, if the thickness deviation exceeds 10%, it is also very easy to wrinkle. At this time, the tension of the composite material can be appropriately increased to extrude it as horizontally as possible with the hot-press rubber roller. However, it should be noted that the tension should be moderate. If the tension is too large, the composite material will be elongated, causing the bag mouth to curl inwards. If the composite material deviation is too large, it can not be used and it will be dealt with separately.

Due to the deviation of the thickness of the material itself, which causes the packaging bags to wrinkle and curl, it must be carefully checked before it is used on machine. If it exceeds 10%, it is best not to use it.

Misoperation also causes wrinkling and crimping

The pressure of the hot-press rubber roller is uneven, and the hot-press rubber roller rotates back and forth during operation, so that the composite material of packaging bags cannot be fed smoothly, resulting in wrinkling and curling.

The solution is: exit the left and right nuts of the hot-press rubber roller, and then re-tighten them, and apply even force. If the cylinder pressure valve locks the hot-press rubber roller, then you should observe carefully and slow down the speed until it touches the end of the steel roller, the pressure of the atmospheric valve is then added to squeeze in parallel, and the pressure indicator gauge is observed to feed in parallel to reduce the chance of wrinkling and curling. 

In actual production, the curling and wrinkling are also related to the temperature of the hot steel roller. If the temperature of the hot roller is too high, the probability of curling will increase accordingly, especially occurred in the BOPP/CPP, BOPP/PE composite structure of composite bags. The high temperature may even cause the PE film to be adhered by the hot steel roller and firmly adhere to it, which not only wastes material but also delays production efficiency.

The treatment method is to stop the machine, and close the hot steel roller temperature control, to cool down before processing. Generally, the temperature of hot steel roller is adjusted with the actual environment and operation effect, as well as with the width and thickness of the packaging bags’ structure. Good temperature control can reduce the occurring probability of curling and wrinkling.

The occurrence of curling and wrinkling is also related to uneven gluing

When the base material of packaging bag is glued, if there is more glue on one side and less glue on the other side, the side with more glue will inevitably bend inward after drying, and even occurs the phenomenon of sticking. If the gluing system of the laminating machine is determined by the gluing roller, the left and right nut rods should be adjusted to make the gluing uniform, if the squeegee system of the laminating machine determines the amount of gluing by the depth of the wire roller, then the angle or front of the blade can be changed.

The best way to detect whether the glue is uniform is to press the glue system with the left and right index fingers to observe its thickness and make the glue even.

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