Common Corrugated Board Defects and How to Fix Them
Even good plants see corrugated board defects. Most have clear causes in moisture, heat, pressure or glue. Use this guide to identify the problem and decide what to check first.
Warping (curled board)
What you see: sheets curl up or sideways instead of lying flat.
Common causes: uneven moisture between the liners, uneven heat on the two sides, or different paper grades on top and bottom.
What to check: paper moisture, preheater settings on each liner, and storage conditions for the reels.
Washboarding
What you see: visible ridges on the board surface that follow the flute lines.
Common causes: too much moisture or too much glue, or liner paper that is too light for the flute size.
What to check: glue quantity and gap, drying, and the paper weight used for the liner.
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What you see: flattened flutes and a thin, weak board.
Common causes: excess pressure between rollers, worn rollers, or board crushed in downstream machines.
What to check: roller gap and condition (see roller guide), belt pressure, and stacking height.
Weak glue bond (delamination)
What you see: liners peel off the flute easily.
Common causes: low glue quantity, poor glue quality, wrong temperature or running too fast for the heat available.
What to check: glue viscosity and level, roller temperature and machine speed.
Wrinkles and uneven flutes
What you see: wrinkled liner or irregular flute shape.
Common causes: uneven reel tension, misaligned reels, or worn rollers.
What to check: reel stand alignment and tension, as covered in our reel stand guide.
Prevent defects with routine care
Regular cleaning, correct settings and good paper storage prevent most defects. Follow our maintenance checklist and keep notes of settings that produce good board.
Frequently asked questions
What is the most common defect?
Warping is very common and usually linked to moisture and heat balance between the liners.
Can paper quality cause defects?
Yes. Uneven moisture or inconsistent paper grade often leads to defects.
Who can help diagnose a problem?
The machine manufacturer can advise on settings and parts. Contact us through the inquiry form.
