A U channel is the same profile described by its fit rather than its shape: the channel is the gap between the two legs, and everything about the part follows from how closely that gap matches the panel. Buyers who order a channel by outer size rather than inner width usually get a protector that either will not go on or will not stay on.
Inner width is the specification
A U channel is ordered by the panel it has to hold, so the dimension that matters is the inside gap, not the outside. A channel quoted as 60 mm outside may have a 50 mm inner width on a 5 mm wall, and on a 20 mm panel that is a loose fit that falls off.
Measure the panel at several points, not once. Board thickness varies across a sheet, and a channel cut to the thinnest reading will be tight at the thick end. Where variation is real, specify the mid-point and accept a light interference fit.
Specification at a glance
The table below is the working set. Inner width follows the panel, leg length follows the face, and wall follows how the pack is handled.
| Panel | Inner width | Leg | Wall |
|---|
| 3-6 mm sheet | 6 mm | 25 mm | 2.5 mm |
| 12-18 mm board | 18 mm | 40 mm | 3-4 mm |
| 18-25 mm board | 25 mm | 50 mm | 4 mm |
| 40 mm worktop | 40-41 mm | 60 mm | 5 mm |
| Wide section | Up to 150 mm | 100 mm | 5-8 mm |
Where channels are used on a packing line
Channels are fitted by hand at the bench or pushed on as a panel leaves a saw. For hand fitting, a slightly generous inner width is faster and the profile still holds; for machine fitting, the channel has to be consistent or it jams the guide.
On a long edge, two short channels at the ends hold better than one long channel that sags in the middle, and they cost less. Long channels are used where the edge itself has to be covered for protection rather than for grip.
Cut ends, dust and the fold
A channel that is cut on site gets a ragged end, and a ragged end is where the profile starts to tear. Order cut to length and keep the ends square.
Keep the channel dry and free of grit before fitting. Grit trapped between the leg and a finished panel face is the most common cause of a scratch that appears after unpacking.
Questions buyers ask before ordering
Do I order by inner or outer width?
By inner width, measured as the gap between the legs. The outer size is the inner width plus two wall thicknesses.
How much clearance should there be?
Aim for light hand pressure. Zero clearance creases the fold; more than a millimetre of slack and the channel will not stay on.
Can I get a channel for a 41 mm worktop?
Yes. Inner width is made to the panel, so 40, 41 or 42 mm are all normal specifications.
Are two short channels better than one long one?
For grip, usually yes, and they cost less. A long channel is for covering the edge, not for holding on.
What is the maximum channel width?
150 mm inner width, bounded by the 260 mm maximum opened width across three faces.
For a quotation, post the product dimensions, load and destination port to mona@hengnicepacking.com.
