Why Does Carton Misalignment Occur During Carton Erecting and Sealing?

2025-12-16

Why Does Carton Misalignment Occur During Carton Erecting and Sealing?

Under normal conditions, a carton should close in a flat and natural manner, with all flaps folding smoothly without interference. However, in some cases, the flaps overlap after closing, with multiple fold lines stacked in the same area. This creates an unstable carton structure even before the erecting or sealing process begins.

The main cause of this issue lies in the folding position of the front and rear minor flaps. These minor flaps are folded too high and end up sharing the same fold line as the major side flaps. As a result, when the machine presses the major flaps, the minor flaps cannot fold naturally and are instead forced downward by compression.

Because the carton material is relatively thick and rigid, and the minor flaps lack chamfering or structural clearance, internal stress builds up when they are forced into position. When this stress is released, it pushes the major flaps outward. This leads to carton misalignment that may shift to the left or right unpredictably, reducing process stability.

Although the carton may appear closed without visible gaps during erecting, this is often because belts or guides temporarily clamp the carton and suppress the interference. As pressure increases during sealing or compression, the internal stress becomes apparent, causing flaps to spring back, lift, or shift. This issue is fundamentally related to carton structural design rather than machine performance, and it can be effectively resolved by trimming the minor flaps or adjusting the crease layout to provide proper clearance.