Is it easy to make a flexible package? No! Never ignore this!
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Compared with the printing and compounding processes, the bag making process is a relatively simple process of mechanical operation, but this does not mean that the problems in the bag making process are simple. Since the bag making process is the last process in the entire flexible packaging production process, some problems of the process are more or less related to the front end process, so the problems in the bag making process are usually complicated, here mainly Introduce a few common problems.
Poor heat seal strength
There are three main reasons for this problem.
(1) Reasons for heat sealing materials
If the thickness of the heat sealing material is not uniform, the heat sealing strength is likely to be poor. At the same time, when the precipitated material is excessive due to poor processing of raw materials and long storage time, it is easy to cause poor heat seal strength.
(2) Influence of printing and compounding processes
The influence of printing: if the temperature resistance of the ink is poor or the additive in the ink is improperly used, etc., the ink layer may be detached during the heat sealing process, thereby causing poor heat sealing;
The effect of compounding: In the dry compounding process, if the adhesive is not cured completely, or the proportion of the adhesive is improper, the composite layer is sticky, and the heat seal strength is also deteriorated;
If the drying is insufficient during the printing and lamination process, the printed layer and the composite layer are delaminated, which may cause poor heat sealing.
(3) The impact of the bag making process itself
In the bag making process, the heat sealing pressure is insufficient, the heat sealing temperature is improperly set, and the heat sealing time is insufficient, which may cause poor heat sealing. In addition, if the cooling time is insufficient, not only the heat sealing edge is not well shaped, but also the heat sealing strength and appearance.
Heat sealing with spots, bubbles
When there are spots or bubbles in the heat sealing edge in the bag making process, the following two aspects should be found.
(1) Raw materials
After the moisture absorbing material such as nylon absorbs moisture during storage or production, it is easy to generate bubbles and spots after heat sealing in the bag making process.
(2) Improper operation
If the adhesive is incompletely cured during compounding, delamination during heat sealing will also generate bubbles and spots. In addition, the heat sealing edge is too wide, the silica gel plate is deformed, the heat sealing cloth is damaged, foreign matter on the heat sealing knife or improper setting of process parameters, etc., and spots and bubbles are generated. Therefore, in the usual production process should pay attention to inspection, timely discovery of problems, and timely processing.
Unit size error
There are five main reasons for the error in the size of the product unit:
The photoelectric head malfunctions, such as poor sensitivity of the photoelectric head, wrong polarity selection, malfunction of the photoelectric switch socket, etc., resulting in poor tracking of the photoelectric head;
The discharge tension is not stable or the discharge speed is too low;
The design of the bag cursor is unreasonable, such as the cursor is too small or the contrast with the background color is too small, so that the photoelectric head is not easy to track;
During the printing and compounding process, the raw material is stretched or shrunk, and the unit size is already inaccurate, so that the pitch of the bag-making cursor changes;
The rubber roller is not clamped to cause the material to slip, so that the fixed length is not allowed.
Seal wrinkle
There are three reasons for the problem of sealing wrinkles:
The thickness of the material is not uniform, and the material appears slack during the blanking process;
The floating roller tension is too small;
Some rollers did not rotate during the operation, resulting in unbalanced material.
Therefore, the above components should be inspected at the time of starting up, and the machine should be adjusted to a better operating state.