Everything a sign maker or fabricator needs to specify, draw and make folded aluminium sign trays and cladding trays: materials, sizes, sheet nesting, toggle joints, fixing angles and finishes. The drawings above are made by the configurator: use them alongside this guide.
- What is a sign tray?
- Solid aluminium or ACM?
- Measuring and sizes
- Sections and sheet nesting
- 2, 2.5 or 3 mm?
- Toggle joints
- Fixing angles and Section A-A
- Thermal movement
- Powder coating and colour
- Drawings and files for production
- Checklist before ordering
- Questions
1 · What is a sign tray?
A sign tray (also called a pan sign, tray sign or folded tray) is a flat sheet of aluminium with its edges folded back to form returns. The returns give the sign depth, hide the fixings and leave clean, square edges. Lettering and logos go on the face: vinyl, printed graphics, fret-cut letters, or built-up letters fixed through the face.
The same folded panel used on a building is a cladding tray or cassette. The geometry is identical; cladding trays usually have returns on all four sides and are fixed to a rail system rather than to angles.
2 · Solid aluminium or ACM?
Trays are made either from solid aluminium sheet folded on a press brake, or from aluminium composite (ACM) that is V-grooved on a router and folded by hand. Both have their place:
| Solid aluminium (2, 2.5 or 3 mm) | ACM (3 or 4 mm composite) |
|---|
| Made by | Laser cut, folded on a press brake, corners welded | Routed with V-grooves, folded, corners bonded or riveted |
| Strength | Stiff, takes heavy letters and fixings through the face | Light; large faces need stiffening |
| Long runs | Sections joined with hidden toggle joints | Joining strips, usually visible |
| Finish | Powder coated in any RAL or BS 4800 colour | Factory colours; others wrapped or painted |
| Core | All metal, no plastic core | Plastic or mineral core between aluminium skins |
| Cost | Higher | Lower |
This guide covers solid aluminium trays, which are what AluTray draws.
3 · Measuring and sizes
All sizes are external, measured over the outside of the metal:
- TL – total run length, end to end.
- H1 – face height.
- R1 – return depth: how far the tray stands off the wall (typically 50–100 mm).
- R2 – lip size: a short second fold on a return, folded out (towards the wall) or in, that stiffens the edge or takes the fixings.
- TH – overall height, the face plus any outward lips.
Returns can be on all four sides, top and bottom only, or none (a flat panel). Ends can be folded closed or left open for a butt against another tray.
4 · Sections and sheet nesting
Aluminium sheet comes in standard sizes, usually 2500 × 1250 and 3000 × 1500 mm. Each tray section is cut as one flat blank, so a section can be no longer than the sheet (less a 20 mm edge trim each side), and the unfolded profile (face plus returns and lips) must fit across the sheet width.
A run longer than one sheet is split into sections. Equal sections are usually the most efficient: identical blanks nest evenly and every part is the same. The configurator tries every section layout (equal, ends plus inner, make-up) on every stocked sheet, nests the face blanks, fixing angles and joiners, and shows the sheets used, the offcut worth keeping and the scrap.
Tip: a face just too tall for a sheet can cost a whole extra sheet. The configurator tells you when reducing the face height by a few millimetres saves a sheet, or makes a smaller sheet usable.
5 · 2, 2.5 or 3 mm?
2 mm aluminium suits smaller trays and lighter faces. For faces over 800 mm, use 2.5 mm: the face stays flatter, oil-canning (a wavy face in raking light) is less likely, and the returns take fixings better. 3 mm is available as a manual choice for heavier or more exposed trays. The thickness also sets the joint: see below.
6 · Toggle joints
Sections are butted tight with a 0 mm gap and held by a hidden toggle joint: a male tongue spot welded to the back of one face and a female S-section spot welded to the back of the next. The female is joggled back to leave a pocket the tongue slides into. Welds are on the back only, so the face is never marked.
The pocket must take the tongue and its powder coat. Allow the sheet thickness plus 1 mm: a 3 mm pocket on 2 mm sheet, 3.5 mm on 2.5 mm and 4 mm on 3 mm. Too tight and coated parts will not go together on site; too loose and the faces will not line up.
7 · Fixing angles and Section A-A
A tray is usually hung on aluminium equal angles fixed to the wall inside the top and bottom returns, with side brackets at each end. The angles stop 5 mm short of each end and are kept clear of the toggle joiners behind the face. The tray is then screwed to the angles through the returns or through an outward lip, so no fixings show on the face.
Section A-A, a cut through the tray, is the drawing to check before anything is made: it shows the face, returns and lips at their true thickness, the joiner and its pocket, and the clearance between the angle tips and the joiner.
8 · Thermal movement
Aluminium expands about 0.024 mm per metre per °C. Allow for a 60 °C swing, typical for a sunny wall, and a 3 m section moves about 4 mm. Each section is pinned at one point with a round hole and fixed through slots everywhere else, so it can move without bowing. Dark colours get hotter: allow more movement, or shorter sections, on south-facing walls.
9 · Powder coating and colour
Solid aluminium trays are powder coated after folding and welding, in any RAL Classic or BS 4800 colour, satin or gloss, or supplied mill finish (uncoated) for wrapping. Fixing angles, joiners and stiffeners are hidden and can stay mill finish. Screen colours are approximate: always confirm with a physical swatch.
10 · Drawings and files for production
A tray drawing set should give the customer, the sign maker and the fabricator what each needs:
- PDF drawing set – 3D view, rear view with fixing angles, Section A-A, fixing holes, toggle join, flat patterns with fold directions, sheet usage and a parts list.
- DXF files – one per sheet, parts nested as quoted, cut lines and fold lines (up and down) on separate layers, ready for the laser.
- Artwork templates – the face at a simple scale (1:1, 1:2, 1:5, 1:10…) for Illustrator or CorelDRAW, with the joints marked, so the customer's logo and lettering can be laid out and scaled back up.
11 · Checklist before ordering
- All sizes external: TL, H1, returns and lips.
- Sheet thickness: 2.5 mm for faces over 800 mm (3 mm on request).
- Section joints placed clear of letters and logos.
- Toggle pocket = sheet + 1 mm.
- Fixing angles clear of the joiners; side brackets at the ends.
- Fixing method for the wall checked by your installer.
- Colour confirmed with a physical swatch.
- Artwork laid out on the template, with joints in mind.
12 · Questions
What is the difference between a sign tray and a pan sign?
Nothing: pan sign, tray sign, folded tray and sign tray all describe the same thing, a flat face with its edges folded back into returns.
How long can an aluminium sign tray be?
There is no limit on the run. It is made in sections, each from one sheet (up to about 2960 mm on a 3000 × 1500 sheet after the edge trim), butted tight and held with toggle joints.
Is 2 mm aluminium thick enough for a sign tray?
2 mm is fine for faces up to 800 mm. For faces over 800 mm, 2.5 mm is advised to keep the face flat and to take the fixings; 3 mm is available too.
How much clearance does a toggle joint need?
The pocket for the male tongue is the sheet thickness plus 1 mm for the powder coat on both parts: 3 mm on 2 mm sheet, 3.5 mm on 2.5 mm and 4 mm on 3 mm.
How do you stop a long aluminium sign from buckling in the sun?
Allow for movement. Aluminium grows about 0.024 mm per metre for every °C, so a 60 °C swing moves a 3 m section by about 4 mm. Each section is pinned at one point and slotted at the others, so it can move without bowing.
Can I get the DXF files for my own laser?
Yes. The configurator nests every part onto your sheet sizes and gives one DXF per sheet, with cut lines and fold lines (up and down) on separate layers.