Common Problems With Corrugated Plastic and What Causes Them

Print Lifts or Scratches Off

Almost always a surface energy problem. Untreated polypropylene rejects ink. Printing grade board is corona treated to 45 dynes on both faces during extrusion, and treatment has a working life, so board that has been in the warehouse a long time may no longer print reliably.

Check that printing grade was actually ordered, and print treated stock rather than storing it first.

Panels Bow or Twist

Usually a weight problem rather than a thickness problem. A 4 mm sheet at the low end of the weight range has thinner skins and flute walls than the same thickness at the high end. Increase weight per square metre rather than thickness where flatness is the issue.

Where equal stiffness is needed in both directions, PP honeycomb board gives homogeneous rigidity rather than stiffness mainly along the flute.

Edges Fray and Collect Dust

Open flutes at a cut edge collect dust and liquid and fray with handling. Sealing or welding the four sides and corners, as done on layer pads, closes the flutes and removes sharp edges.

Boxes Lose Shape After a Few Trips

Check the load case against the specification. Stack height, product weight and the number of trips all drive the sheet weight required. A box specified for a single shipment will not survive a returnable loop.

Static Damage Continues After Switching to Plastic

Check which grade was supplied. Anti-static grade covers 1×10⁸–1×10¹⁰ Ω and conductive grade covers 1×10³–1×10⁵ Ω, and they are not interchangeable. Conductive grade is black, so a coloured container is not conductive grade.

Protection Board Is Scratching the Floor It Protects

Grit under the board. Clean the surface before laying, butt the joints and tape them so grit cannot migrate underneath.