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During the autumn and winter seasons, as the temperature drops, the weather also becomes increasingly dry. When packaging factories produce cardboard boxes, there is a tendency for the paper to burst, which not only increases the waste rate but also raises the production costs of the enterprises. So, how can this problem be solved?
Improvement measure 1: Maintain the environmental humidity during storage in the warehouse
Mobile humidification, floor sprinkling humidification, and moderate humidification are all beneficial for enhancing the suitability of the paper production process.
Improvement Measure 2: Increase humidity on the back side during the post-printing lamination process
When applying the film, use an ultrasonic humidifier to humidify the backside of the paper to enhance its softness.
Improvement Measure 3: Paper Humidification
1. Paper that remains in a dry environment for a long time or is dried after coating is prone to losing moisture, resulting in creasing, cracking, and other problems during die-cutting.
2. Applying water to the paper for humidification, increasing its flexibility, and then performing die-cutting and creasing can reduce the occurrence of such issues.
For example: Watering the printing machine (on the back of the paper)
For example: Replacing the oil coating in the coating machine with clean water (without drying)
Improvement Measure 4: Rational selection of indentation strips during production
According to the SOP, select the appropriate indentation knife and indentation strip
1. Measure the thickness of the paper first ➨ For example: 0.31mm
2. Select the appropriate indentation knife ➨ Choose 1.0mm
The paper bag must consider that the folding radius of the double-layer paper position is sufficient to withstand the external tension of the indentation. The width of the indentation knife is recommended to be increased by one level.
3. Select the correct indentation strip ➨ Choose a height of 0.4mm x width of 1.6mm
Calculation of indentation strip height: Paper thickness + 0.05mm = 0.31 + 0.05 = 0.36mm
Calculation of indentation strip width: Paper thickness x 2.0 + indentation knife = 0.31 mm x 2.0 + 1.0mm = 1.62 mm
Improvement Measure 5: Increase the indentation width and reduce the pressure buffer during the production process.
Improvement Measure 6: Details of the Automatic Bagging Machine in the Production Process
The bottom-lifting device of the automatic hand-held bag forming machine is more likely to cause paper tearing compared to manual bag formation. Therefore, it is particularly important to maintain normal environmental temperature and humidity (23 ± 3℃, 50 ± 5%) at all times.
2. During the pressing process, the bottom of the easily-tearable area is relieved of pressure, and a buffer zone of about 1 cm is reserved. This has a certain improvement effect on the tearing process.
The multi-layer folded part bursts, usually manifesting itself when the bag is formed.
The causes of bursting:
① The paper is thick, has a high stiffness, low folding endurance, and the environmental temperature and humidity are too low, without coating;
② The die lines are not standardized, and multiple cuts are made;
③ The bag-forming method is not standardized, the die lines are not aligned properly, and the folding force is too strong.
Common bursting locations of hand-held bags - the side corners and the inner side crease lines.
The bursting of the side corners and the inner side crease lines (the cross-shaped area) is usually caused by stretching the bag:
① The paper is thick, has a high stiffness, low folding endurance, and the environmental temperature and humidity are too low;
② The die lines are not standardized, multiple cuts are made, and the bag type is wide and difficult to open;
③ The bag-forming method is not standardized, and the stretching action is not proper.
During the dry autumn and winter seasons, many friends in the paperboard and carton industry often mention various problems such as broken edges on the surface paper, broken edges inside the carton, and broken or cracked binding lines. Now, let's analyze the causes of these broken edges and the factors that influence them.
Analysis of the root cause of paper box burst lines:
1. The tensile strength of the inner and outer paper decreases, while the rigidity of the paperboard increases, thereby increasing the possibility of burst lines in the packaging box.
2. The flat pressing strength of the paperboard core increases, while the toughness of the inner and outer paper decreases. During the process of applying the burst lines, the inner paper is prone to be damaged, resulting in burst lines of the box.
3. The inter-layer bonding strength of the white card paper is insufficient. The internal bonding strength of the boxboard is an issue that packaging box manufacturing enterprises often overlook.
2. Factors influencing the bursting of carton seams:
1. The influence of environmental temperature and humidity, especially the control of moisture content. When the moisture content is below 60%, the seams are most likely to burst.
2. The weaker the tear resistance of the carton board, the more prone it is to bursting. Generally speaking, kraft paper is more tear-resistant than uncoated paper; softwood pulp is more tear-resistant than hardwood pulp; paper made from raw materials is more tear-resistant than recycled paper.
3. The more layers the cardboard has, the more likely it is to break the wires. For example, triple-ply cardboard is more prone to wire breakage than double-ply cardboard; double-ply cardboard is more prone to wire breakage than single-ply cardboard.
4. The greater the difference in the paper and tissue paper quantities inside the carton, the more likely it is to burst the seams.
Improper operation during the slotting process of printing can also cause the paper boxes to burst the seams.
6. The greater the strength of the paper, the more likely it is to burst the thread.
