Which coil width minimises offcuts on your blank order?
Two worked layouts — Ø600 discs and 1200 × 600 rectangles — on 1000 mm and 1250 mm coil, with the yield arithmetic shown so you can check it, plus what happens to the offcut strip.
Which coil width gives the best yield? (quick answer)
Coil width decides your offcut rate before anything else happens. For a Ø600 mm circular blank, a 1000 mm coil carries one row of circles and yields about 47% of the strip as product, while a 1250 mm coil carries two rows and yields about 75% — the same discs, the same length of coil. For 1200 × 600 mm rectangles the gap is 60% versus 96%. If your size list cannot use the offcut strip, the wider coil is almost always the cheaper order.
Yield here is simply the area of finished blanks divided by the area of coil consumed. Because blank sizes repeat, the arithmetic comes down to one question: how many blanks fit across the coil width, and what happens to what is left over. The two worked examples below cover the cases buyers meet most — discs and rectangles — and every number can be re-derived from the dimensions shown.
How much does a second row of discs buy? — the Ø600 maths
Take a Ø600 mm circular blank, the common size behind many 600 × 600 warning faces. In straight nesting the circles sit tangent along the coil, so each circle consumes 600 mm of coil length, and across the width each row consumes another 600 mm.
On a 1000 mm wide coil, one row fits and a 400 mm strip runs the whole length as offcut. Per linear metre: 1/0.6 = 1.667 circles × π × 0.3² = 0.471 m² of discs against 1.00 m² of coil — 47.1% yield. On a 1250 mm coil, two rows fit (2 × 600 = 1200 mm, with a 50 mm trim): 3.333 circles = 0.942 m² against 1.25 m² — 75.4% yield. The second row is what turns two-thirds waste into one-quarter waste.
| Blank | Coil width | Rows across | Blanks per coil-metre | Yield |
|---|---|---|---|---|
| Ø600 disc | 1000 mm | 1 | 1.67 | 47.1% |
| Ø600 disc | 1250 mm | 2 | 3.33 | 75.4% |
| 1200 × 600 rect. | 1000 mm | 1 | 1.00 | 60.0% |
| 1200 × 600 rect. | 1250 mm | 2 | 2.00 | 96.0% |
Derivation for the rectangle: on 1250 mm, two 600 mm columns fill 1200 mm; each coil-metre delivers 2 × (1.0 × 0.6) = 1.20 m² of panels against 1.25 m² consumed. Staggered (hex) nesting of discs on the 1250 mm coil raises the theoretical ceiling to π/(2√3) ≈ 90.7% before trims.
What happens to the offcut strip?
The 400 mm strip from the 1000 mm coil is only waste if nobody can use it. Two things decide whether it becomes scrap or product:
Slitting. We slit master coils to width before blanking, so a 400 mm strip can be re-slit into the narrower widths another size on your order needs — for example two 190 mm strips for 900 × 190 destination-blade sizes, plus trim. The strip is only lost when your order contains nothing narrower than the offcut.
Mixed-size shipping. Blank sizes from the same master coil can be packed on the same pallet, so the second size does not have to wait for its own production run. Tell us the full size list, not just the dominant size, and the layout is planned across all of it before the first cut.
How tight is the slit width tolerance?
Slit-to-width strip is what the blanking line actually runs on, so the width tolerance matters to your finished blank tolerance. Width tolerances for mill and slit aluminium strip are specified in EN 485-4, the CEN standard covering tolerances on shape and dimensions for aluminium sheet, strip and plate. The practical point for buyers: the tolerance on a slit width is tighter than the tolerance you would get by guillotining a wide sheet in-house, because the strip is slit once, under tension, on gauge-controlled slitters — not re-squared blank by blank.
Send the complete blank size list with quantities — discs and rectangles together, including the small sizes you might leave out. We plan the slitting pattern across all of it, quote the yield you will actually get, and flag any size that would strand a strip. The quoted per-blank price already reflects the planned layout; there is no separate scrap charge to negotiate.
Width and shape tolerances for aluminium sheet and slit strip referenced in this note follow EN 485-4, “Aluminium and aluminium alloys — Sheet, strip and plate — Part 4: Tolerances on shape and dimensions for cold-rolled products”, published by CEN; the US-market equivalent for flat-rolled products is ASTM B209 from ASTM International.
Sources: CEN, Brussels · ASTM International, West Conshohocken, PA. Cited 1 November 2026.
Questions on this note
Which coil width should I order for a mix of disc and rectangle blanks?
Send the full size list and we plan the slitting pattern across all of it. As a rule, 1250 mm covers two 600 mm columns — one Ø600 disc row pair or two 1200 × 600 rectangle columns — while 1000 mm only makes sense when a narrower size on the same order can use the 400 mm balance.
Does staggered nesting really help with round blanks?
Yes. Offset rows let circles pack tighter, with a theoretical ceiling of π/(2√3), about 90.7%, versus 78.5% for straight rows over an infinite sheet. On real coil widths the staggered layout needs roughly 1120 mm across for Ø600, which is why the 1250 mm coil is the one that can use it.
Can I get a coil width that is not in your standard list?
We slit to width on the same line that feeds the blanking press, so a non-listed width is quoted against the drawing. The master coil range runs 1000–2000 mm, which covers most sign and traffic-blank layouts.
Do I pay for the offcut strip?
No. The quotation is per finished blank; the slitting pattern is our planning problem, and the planned yield is already inside the price. If a size on your list rescues a strip that would otherwise be scrap, that saving shows up in the per-blank price.
Related
Send the drawing, get a written answer
Specification questions are answered by the same person who quotes the job.