Common cardboard problems and solutions

Nowadays, the production process of corrugated cartons is more and more sophisticated, but there are still many quality problems in actual production. For the majority of carton manufacturers, solving the cardboard problem is the key to improving the quality of finished cartons.

"Board" cardboard

As Corrugated paper corrugations undulate, the face paper does not evenly tighten on the surface of the paperboard. It is shaped like a “sawboard” or “sawboard” paperboard. The reasons for its formation are:

The viscosity of the paste is too large or the amount of paste is too much. When the peak is pressed against the tissue paper, the excess paste is squeezed out to the sides of the peak, creating a much wider paste area than is actually required in the width of the peak. The paste dries and shrinks, causing the tissue to be pulled down on both sides of the corrugated peak, forming a "sawboard" that exposes the surface to scars. Papers with higher grammage weights have higher rigidity and can resist this kind of shrinkage. The amount of sinking should be less. Therefore, when using thinner or lighter gram papers, pay attention to reduce the amount of upper paste, that is, Reduce the gap between the paste and the paste to reduce the occurrence of "seesaw" phenomenon.

After the corrugating roll wears, its peak radius increases. Therefore, it is easy to absorb more adhesives and it is easy to cause the phenomenon of "seesaw".

Paste does not coordinate with the speed of the lower corrugating roller, so the adhesive is concentrated on one side of the shoulder, causing the face sheet to shrink on one side.

The moisture content of the tissue paper is too high, causing the shrinkage of the tissue to subside after the adhesive dries.

Cardboard curl

Cardboard warpage refers to the fact that the paperboard is raised or recessed in a relatively large area. There is a kind of cardboard warping called "positive curvature", also known as "warped upwards," that is, the cardboard convex to the side of the paper. On the contrary, it is "inverse curvature". One side is convex and the other side is concave. It is "S-curvature", and the warpage that starts with the diagonal of the cardboard is the "warped twist." The axis of warpage is parallel to the direction of the corrugation and is called "warp in the length direction." The use of curved cardboard as a carton, molding can not be square, affect the appearance, instability of compressive strength. Curved paperboards are not easy to accumulate and cannot enter the printing press smoothly, which seriously affects the printing effect and the precision of slotting and die cutting.

The fundamental reason for the curling is that the paper shrinks unevenly and is caused by the different extent of the various components of the cardboard. Different paper moisture content, the degree of contraction will be different. When the paper board and the inner paper have different telescoping degrees, the paperboard is likely to cause warp. Using thicker and heavier papers than thin papers and low heavier papers, the stretching is relatively stable and not easily deformed, so when the thickness and weight of the different facial papers and liners are different, the cardboard is likely to produce music. Alice, so in the carton design stage of the paper, should make the surface of the paper weight and thickness equal to or close to.

In production, the shrinkage of the paper can be controlled by adjusting the heat to reduce the degree of curling of the paperboard. The reason for the "positive curvature" is generally because the paper and single corrugated paper are too wet and the paper is too dry. Therefore, the drying of the paper and the single corrugated paper should be strengthened, and the warm-up of the noodles should be reduced. Appropriate measures, such as increasing the preheating area of ​​corrugated paper and liner paper on single-sided machines, lowering the temperature of the hot plate, appropriately increasing the speed of the vehicle to reduce heat transfer, and reducing the amount of paste on the single-sided machine, can largely avoid Paper curls. The reason for the reverse is that the reason is that because the single-sided corrugated sheet is too dry and the sheet of paper is too wet, the opposite method can be used for control. "S-curve" is usually due to the edge of the paper is too wet, resulting in a serious shrinkage of the base paper, can make up for the increase in the warm-up time of the base paper; the other cause of curling is due to the difference between the weight of the upper and lower paper is too large, you can adjust the paper, Reduce the appearance of this phenomenon. "Twisted and warped" is caused by poor quality of the base paper, uneven moisture distribution in various places, uneven temperature distribution on the hot plate, etc., and corresponding rectification of these aspects. “Changing in the length direction” is caused by inappropriate tension and the web tension can be adjusted.

The above problem of curling can also be improved with a spray device. For the curled paper board that has been produced, it should be turned immediately. The high temperature and high humidity characteristics of the paper board when it emerges are stacked in time. The board is pressed with a wooden board, and then pushed to the ventilated area to dissipate heat for 4 to 8 hours. The paperboard is relatively flat.

High and low

“Sorghum” refers to fully formed corrugated, ie, the height of the crucible reaches the standard or is consistent with the tooth depth of the corrugating roll; and the “low” is the corrugated without the complete molding, and the height of the crucible is usually lower than the standard value or lower than the corrugation. Roller tooth depth. When the core paper is rolled and bonded with the paper, the high and low blemishes are present at the same time and are called “high and low blemishes”.

Low enthalpy is one of the reasons that affect the quality of corrugated board. Due to the low height at the low enthalpy, poor adhesion or adhesiveness to the vellum, affecting the adhesive strength of the paperboard, resulting in a decrease in the side pressure strength and the flat pressure strength and due to low The appearance of blemishes, uneven surface and affect the appearance and printing effect.

The reasons for the high and low defects and their solutions are roughly the following:

The corrugating rollers are not parallel and the bearing at both ends is worn. The corrugating roller vibrates at high speed. Check the adjustment of the parallelism of the corrugating roller, adjust the bearing clearance or replace the bearing, and reduce the speed to avoid the resonance zone.

Insufficient pressure between corrugating rollers should increase the pressure.

Corrugated rollers have waste paper or other impurities in the splines and should remove impurities.

The high or low moisture content of the corrugating medium paper can affect the forming of the corrugating medium. When it is too wet, the warm-up area should be increased, and when it is too dry, the amount of spray should be increased.

The corrugated paper roll is not round, and the rotation is not uniform during operation. Tension should be increased or the original paper replaced.

Fall down

The collapse is that the corrugated sloping to one side, the sloping corrugation leads to the cardboard thickness is not enough, the strength is reduced. Corrugated cardboard is subject to pressure friction and dragging as it moves during processing. Therefore, the rollers must be parallel to the processing surface and maintained in good lubrication, so that the rollers rotate flexibly to reduce friction. The specific causes of the collapse and solutions are as follows:

Between the upper and lower corrugating rollers and between the lower corrugating roller and the pressure roller is not parallel or the pressure is too large, the parallelism between the rollers should be checked, and the pressure between the rollers should be moderate.

Single-sided corrugated cardboard is too strong.

When gluing single-sided corrugated cardboard, the gap between the rider and the paste is too small.

Corrugated paper core paper is too high, should increase the preheat area to reduce the amount of spray.

There is debris on the hot plate and it needs to be removed.

Pressure burst

When the corrugated cardboard is folded, the pressure line breaks, and the main causes and solutions are as follows:

The gap between the pinch rollers is too small and the gap should be adjusted.

The reel is not round and the reel needs to be replaced.

Roller shaft bent, need to replace the pressure roller shaft

---Carton Technology