Insufficient sealing is one of the common faults of continuous sealing machines. Insufficient sealing has three meanings: 1. The sealing part of the packaging bag cannot be sealed; 2. Under the pressure of the sealing knife, although the bag is sealed, it is squeezed with a little force or When peeling off, the seal is cracked again; ③When the peeling test is performed on the seal, half of the seal is firm and half is separated. The sealing quality of such a bag is still unqualified, because the contents are squeezed very hard during storage and transportation. easy to miss. This situation often occurs when the composite lining is OPP and blow-molded PE.

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The main reasons for the first failure are as follows.
(1) The heat sealing temperature is not enough
Under normal circumstances, when the composite bag with OPP as the lining material, when the total thickness of the bag is 80-90 μm, the heat sealing temperature should reach 170-180 ℃; the total thickness of the composite bag with PE as the lining material is 85-100 μm At this time, the temperature should be controlled at 180 ~ 200 ℃. As long as the overall thickness of the bag is increased, the heat sealing temperature must be increased accordingly.
(2) The heat sealing speed is too fast
The inability to seal the mouth is also related to the speed of the sealing machine. If the speed is too fast, the sealing part will be transported by the traction roller to the cold pressing place for cooling treatment before it can be heated, which will naturally fail to meet the requirements of heat sealing quality.
(3) The pressure of the cold-pressed rubber wheel is not suitable
There are two cold-pressed rubber wheels on the top and bottom, and the pressure between them should be moderate. When adjusting the pressure, you only need to clamp the spring.
(4) There is a problem with the quality of the heat-sealing film
The failure to seal the seal is also related to the quality of the heat-sealing film. If the corona treatment of the composite lining is uneven, the effect is not good, and it happens to appear at the seal, and it will definitely not be able to seal. This situation is rare, but when it occurs, the product is bound to be scrapped. Therefore, in the color printing and packaging industry, the next process supervises the previous process. Once a quality problem is found, the cause must be analyzed and solved in time.
If there is moisture or dirt on the seal, it will also cause the seal to be weak.