A cut metal edge is the hardest thing a paper protector has to survive. The edge is thin, straight and sharp, and under band tension it behaves like a blade. The answer is not a thicker board in the middle but more material exactly at the edge line, which is why sheet metal protection is specified by wall build and edge doubling rather than by leg width alone.
Profile data for sheet metal
| Material | Wall | Edge treatment |
|---|
| Cold rolled sheet 0.5-1 mm | 3 mm | Single board, 50 mm leg |
| Plate 3-6 mm | 4 mm | Doubled at the band line |
| Plate above 6 mm | 5 mm | Doubled, 60 mm leg |
| Oiled sheet | 4 mm | Rougher face, no slip |
| Coated or painted sheet | 3 mm | Dry board, natural kraft |
How a sharp edge defeats a light board
A 2 mm steel edge under a band at moderate tension concentrates on a contact line a fraction of a millimetre wide. A 3 mm paper wall will be notched on the first tensioning, and once notched it tears along the band line during vibration.
Doubling the board at the edge, or specifying a 5 mm wall, moves the contact from a line to a strip. The practical test is simple: fit one corner, tension the band, release it, and look at the board. A visible notch means the specification is wrong.
Oiled and coated sheet
Oiled sheet is slippery and the protector slides while the band is tensioned. A board with a rougher outer face holds better than a calendered one, and the band should be positioned so it does not have to slide into place.
Coated sheet, such as pre-painted or galvanised, marks easily. Natural kraft against a dry coated surface is safe; a board that has absorbed moisture is not, because the moisture and any residual oil can leave a stain that shows after installation.
Sheet stacks, coils and blanks
A flat stack is banded across its width, so the protectors go on the two long edges at each band position, not only at the four corners. A coil is a different problem and needs a heavier wall because the band follows a curved surface.
Blanks and offcuts in a stillage need edge protection where they touch the stillage frame, not around the pack. Protecting the wrong edge is a common waste in sheet metal plants.
Questions buyers ask before ordering
Will paper protect the band from a sharp steel edge?
It will, if the wall is matched to the edge. A 3 mm board on a 6 mm plate edge is not enough and the band will notch it.
Can I reuse the protectors on the next lift?
No. A notched board will tear. Reuse is only realistic on blunt edges such as timber or plastic sections.
Do you supply V boards for coil edges?
Yes, folded profiles at 60, 90 or 120 degrees, but coil protection normally needs a heavier wall than flat sheet.
What about rust between the board and the sheet?
Keep boards dry and do not store opened bundles on a concrete floor. A damp board against steel is a rust risk over a long sea leg.
Can the boards be cut to the exact stack width?
Yes, to the millimetre, with bundles labelled by length.
Samples and prices are issued from mona@hengnicepacking.com once cut length, wall thickness and quantity are known.
