The outer diameter is the coverage dimension. It is the inner diameter plus twice the ring width, and it decides how far the protection reaches in from the rim. Buyers often quote it without realising it is derived: change the ring width and the outer diameter changes with it, while the inner diameter stays fixed to the product.
It is a result, not an input
A ring is specified by the product diameter and the band width you want. The outer diameter is what those two produce. Quoting an outer diameter alone leaves the inner diameter and the coverage ambiguous.
That ambiguity is why two suppliers can quote the same outer diameter and deliver parts that look different on the product: one has a wide band with a small hole, the other a narrow band with a large hole.
Specification at a glance
The table shows the relationship in the form it is used on a drawing.
| Item | Value | Note |
|---|
| Inner diameter | Measured product OD | Fixed by the product |
| Ring width | Radial band in mm | Your coverage decision |
| Outer diameter | Inner plus twice the width | Result |
| Clearance | Keeps features clear | Coil eye, core, label |
| Board thickness | By handling | Wide rings need more |
How much face should be covered
Coverage should reach past the rim and stop before any feature that needs to stay clear, such as a coil eye, a core, a label or a strap crossover. That is the practical limit, not a standard percentage.
Wider coverage spreads load better and uses more board. Where the ring is held only by a push fit, a very wide ring can droop at the outer edge; that is where a heavier board earns its cost.
Outer diameter and the pack outline
A ring that projects beyond the product changes the packed outline and therefore the pallet or carton dimension. On a tight loading plan that matters, so the outer diameter belongs in the packing calculation, not only on the ring drawing.
Questions buyers ask before ordering
Is outer diameter the size I order?
Better to order inner diameter plus ring width; outer is derived.
Can two rings share an outer diameter?
Yes, with different inner diameters and bands, which is why the outer alone is ambiguous.
How wide should the band be?
Wide enough to cover the rim and reach past the strap path, stopping short of features that must stay clear.
Does a wider ring need a heavier board?
Usually yes, because a wide ring can droop at the outer edge.
Does the ring change the pack size?
It can. Include the outer diameter in the loading plan.
Tell us the ring diameter, quantity per shipment and how it is fitted at mona@hengnicepacking.com and we will advise on the board build.
