The bend angle of a U protector is the angle between the two halves after folding, measured on the inside of the corner. Two people measuring the same pack will often quote different numbers because one measured outside and one inside. Getting that convention right before ordering is worth more than any tolerance discussion afterwards.
Inside, outside and the board thickness
A 90 degree corner has a 90 degree inside angle and a 270 degree outside angle. If the protector is specified by the outside, the part comes out wrong by twice the board thickness in leg position.
The convention we use is the inside angle, the one the panel sits in. State it in the order and there is nothing to argue about at inspection.
Specification at a glance
The table shows how the angle relates to the notch and to the pack. Only the first column is what you order.
| What you order | What it means | What to send |
|---|
| Inside angle | The angle the panel sits in | Degrees, inside |
| Radius | Corner is not sharp | Radius plus angle |
| Notch width | Set by us from the angle | Not needed |
| Leg position | Follows the angle and wall | Checked on a sample |
| Tolerance | Degree or two from the notch | Agree at order |
What changes the angle after production
Little does. The notch is cut, so the fold stops where the notch closes. A piece can be opened slightly by hand, but closing it further creases the leg and the crease stays visible on the pack.
Humidity moves paper, and a very dry or very damp store will change the fold by a degree or two. That is one reason a heavy wall is not automatically better for an angle-critical pack.
Angle, radius and the corner that is both
A corner with a radius is not one angle. The profile has to follow the radius, so the notch is opened and the piece takes an effective angle wider than the nominal one.
Send the radius as well as the angle. Without it the part is made to the sharp corner and stands off the radius.
Questions buyers ask before ordering
Do you measure inside or outside?
Inside, the angle the panel sits in. State the convention in the order.
Can the angle be adjusted after delivery?
It can be opened slightly. Closing it further creases the leg permanently.
Does humidity change the angle?
By a degree or two in a very dry or very damp store.
What if the corner has a radius?
Send the radius as well. Without it the part is cut for a sharp corner and stands off.
Is a heavier wall better for angle accuracy?
Not necessarily. The notch sets the angle, and a heavy wall is harder to open slightly.
Share the section drawing or a pack sample with mona@hengnicepacking.com and we will confirm feasibility before quoting.
