Most U channels are assumed to fit a rectangular panel. An irregular profile, whether a chamfered board, a moulded trim or an extrusion with a lip, has a section that changes along its length, so a single inner width cannot grip everywhere. The answer is usually a section made to the widest point with relief cut where the profile narrows.
The section is the drawing, not the thickness
A standard channel is specified by one number because the panel is one thickness. An irregular profile has a high point and a low point, and the protector has to clear the high point while still holding somewhere.
That means the channel is drawn to the section, with the legs cut or scored where the profile steps. A generic channel forced over it will sit on the high point and rattle everywhere else.
Specification at a glance
The table shows the usual ways of handling a section that is not a rectangle. The choice depends on whether the pack needs grip or just coverage.
| Profile | Approach | Note |
|---|
| Chamfered board | Widen to the chamfer | Trim legs off the face |
| Moulding with a lip | Relieve or score the leg | Fold around the lip |
| Hollow extrusion | Bear on the outer faces | Never push inside |
| Tapered section | Size to the widest point | Add notch relief |
| Changing section | Sample first | Drawing is not enough |
Chamfers, mouldings and extrusions with a lip
A chamfered board is the simplest case: the channel is widened to the chamfer and the legs are trimmed so they do not stand off the face.
A moulding or a trim with a lip needs the leg relieved, otherwise the lip holds the protector away from the body and the piece sits loose. A scored leg folds around the lip instead.
An extrusion with a hollow section needs the channel to bear on the outside faces only. Anything pushed into a hollow will crush it.
Sampling before volume
Irregular sections are where a drawing is least reliable, because the drawing rarely shows the tolerance that matters. Send a cut sample of the profile and the protector is made to the sample.
The first run is a short one, checked on the actual pack, before the volume order. That costs a week and saves a batch.
Questions buyers ask before ordering
Can you make a channel for a non-rectangular section?
Yes, from a cut sample of the profile rather than a drawing alone.
Will a standard channel work on a chamfer?
It will sit on the high point and be loose elsewhere. Widening it is usually enough.
How do you handle a lip or a flange?
The leg is scored or relieved so it folds around the lip instead of standing off.
What about a hollow extrusion?
The channel bears on the outside faces only, so the hollow is not crushed.
Do you make a sample before volume?
Yes, and for irregular sections we recommend it.
Send the panel thickness, the corner angle and the pack drawing to mona@hengnicepacking.com and we will quote the protector that fits.
