Corrugated cardboard warping problem and solution

The warping of corrugated cardboard is a very troublesome problem, which will seriously affect the quality of the subsequent printing and slitting processes. The reason for the warping of corrugated cardboard is very simple, that is, the moisture content or thickness of the inner paper and the face paper are inconsistent.

If it warps up, the reason is: the moisture content of the face paper is greater than that of the inner paper. If it warps down, the reason is: the moisture content of the face paper is less than that inner paper, or the weight of the inner paper is higher than face paper. After determining the cause of the cardboard warping, it is necessary to solve it according to the direction of the cardboard warping.

When the cardboard is warping, you can turn on the heat source of the preheating roller on the single facer, and turn off the heat source of one or two lining paper preheating rollers at the same time, and reduce the machine speed accordingly. If there is still warping, you should increase the heat source of the face paper preheating roller (add electric heating tubes, increase air pressure, etc.) or increase the wrap angle of the face paper on the preheating roller (adopt methods such as adding tensioning shafts or adjusting the position of tensioning shafts). If it still cannot be solved, you need to spray humidification on the lining paper to make the moisture content of the lining paper and the face paper close to the same.

When the cardboard warps downward, turn off the heat source of the flute paper preheating roller on the single-face corrugator, and turn on one or two lining paper preheating rollers at the same time. If there is no degumming, increase the speed accordingly. If there is still warping, increase the heat source of the lining paper preheating roller or increase the wrap angle on the lining paper preheating roller. If it still cannot be solved, spray humidification is also needed for the face paper to make its moisture content close to that of the lining paper.

When the cardboard "S"-shaped warping occurs, it is generally caused by uneven moisture distribution of the face paper. According to the warping situation, the amount of glue can be adjusted according to the above warping reasons, or the face paper with too low moisture can be sprayed and humidified locally.

It is best to use a moisture tester to measure the moisture content of the lining paper and face paper respectively before starting the machine, and then control the temperature of each roller according to different moisture contents. Generally speaking, when the cardboard is off the machine, let it keep a slight upward warp and adopt the positive and negative stacking method. After about an hour, the cardboard will completely return to a flat state.

We -- CHEYOE GROUP specialize in providing spray humidification systems for corrugated cardboard production lines to help customers solve warping problems. Welcome to contact us!