Aluminium sheet and coil look simple, but a vague order such as "1 mm aluminium sheet" can lead to the wrong alloy, the wrong hardness, poor flatness or a surface that fails after fabrication. Use this checklist when you prepare an enquiry or check an offer. It works for plain sheet, coil, plate, chequered sheet and colour-coated material.
1. Alloy
Pick the alloy for the job, not just the price. Common choices:
- 1050 and 1100: high purity, excellent formability and conductivity, low strength. Used for reflectors, chemical equipment and general sheet work.
- 3003: a little manganese for more strength while keeping good formability. Used for utensils, roofing, ducting and heat exchangers.
- 5052 and 5083: magnesium alloys with good strength and corrosion resistance, used for marine parts, tanks, truck bodies and enclosures.
- 6061 and 6082: heat-treatable, used for machined plates and structural parts.
- 7075: high-strength, for aerospace, tooling and moulds.
Our aluminium sheet grades buying guide goes deeper into each alloy.
2. Temper
The same alloy can be soft (O), half hard (H14, H24), full hard (H18) or heat-treated (T6, T651). Temper decides whether the sheet bends without cracking and how strong the finished part is. Always state alloy and temper together, for example 3003-H14 or 6061-T6. See alloy and temper codes if you need a refresher.
3. Thickness and tolerance
- Specify nominal thickness and the allowed tolerance, or the standard the tolerance follows.
- For thin gauges, a small tolerance difference changes weight per sheet and cost per piece.
- If you buy by weight, check that the supplier is not rolling to the bottom of the tolerance to give you more area per kg, or the top to sell you more weight, depending on what you need.
4. Width, length and coil details
- Sheet size or coil width, and length or coil weight
- Coil inner diameter and maximum outer diameter or weight to suit your decoiler
- Edge condition: mill edge or slit edge
- Whether you need cut-to-length, slitting or circles from coil
5. Flatness and shape
Flatness matters for laser cutting, CNC machining, panels and lamination. Specify flatness requirements or reference a standard, and ask whether material is tension-levelled or stretched. Plates for machining should be stress-relieved (for example T651) to limit distortion after cutting.
6. Surface quality
State the Surface quality you need: commercial mill finish, bright finish, anodising quality, or embossed or chequered. For anodising or visible parts, ask for anodising-quality material and agree on acceptable marks, scratches and roll lines. Request protective film where surfaces will be visible.
7. Coating
For colour-coated sheet and coil, specify:
- Coating type, such as polyester, PVDF or other systems
- Coating thickness on the top and reverse sides
- Colour reference and gloss level
- Required tests: adhesion, bend, impact and weathering where relevant
8. Mechanical properties and certification
Ask for a mill test certificate with chemical composition, Tensile strength, proof strength and elongation for each lot or heat. Check that results match the standard for the alloy and temper ordered. For some products, BIS certification may be mandatory; check the current position under the relevant quality control order.
9. Packing and marking
- Sheets on wooden pallets or in wooden cases, with moisture barrier wrapping
- Coils eye-to-sky or eye-to-wall as your unloading equipment requires
- Interleaving paper or film for bright or coated surfaces
- Marking with alloy, temper, size, lot number and weight
Water stains from condensation are a common complaint. Keep packed material dry and avoid sudden temperature changes during storage.
10. Commercial terms
- Rate basis: per kg, per MT or per sheet, and whether it is linked to LME or MCX
- GST, freight and unloading responsibility
- Delivery schedule and partial delivery terms
- Payment terms and what happens if material is rejected
11. Inspect on arrival
Check every delivery before it goes into production. Measure thickness at several points across the width, check sheet size or coil width, look for water stains, scratches and edge damage, and match the coil or bundle tags to the test certificate. For colour-coated material, compare the colour with your approved sample under good light. Report problems quickly with photos; most suppliers accept claims more readily when they are raised before the material is cut or formed.
Use our guide on writing an aluminium RFQ to put all of this into one enquiry. Then post it under sheets and coils and the AluminumBazaar desk will collect comparable quotes from verified rollers and stockists.
