In this article, I will introduce what aluminum sheet, coil and circles are, how alloy and temper are named, where each form is used, and what a buyer should send before the blanks are cut.
What is aluminum sheet, coil and circle?
Aluminum sheet, coil and circles start from the same flat rolling process. Sheet is cut flat. Coil stays wound for a continuous line. A circle is a disc blanked from sheet or coil for spinning or deep drawing, which is why cookware, lamp parts and traffic signs ask for circles instead of rectangular sheet. Pipe and bar are not circles. They are separate aluminum lines.
The alloy series is the first cut. 1xxx alloys such as 1050, 1060 and 1100 are commercially pure aluminum, soft and conductive, used for reflectors, chemical equipment and many circles. 3003 adds manganese and is the common general sheet for forming. 5052 adds magnesium and is chosen for higher strength and for marine or transport sheet. 6061 is a heat-treatable alloy used for plate and machined or structural parts, often in T6. These four are examples buyers meet constantly. The drawing may name another alloy. That alloy is the order.
How alloy and temper decide the part
Temper is the strength and the ductility after rolling or heat treatment. O is annealed, the soft condition used for severe forming. H tempers are strain hardened. H14 and H24 are typical half-hard names buyers write on 3003 sheet. T tempers are heat treated. T6 on 6061 is solution treated and artificially aged, and it is not a forming temper for a deep pot. A size that is right in the wrong temper cracks in the press or arrives too soft to hold a panel.
Sheet is ordered by alloy, temper, thickness, width and length. Coil adds coil weight and inner diameter. A circle is ordered by alloy, temper, thickness and diameter, plus the edge the press needs and whether the blank is a full circle. Surface matters when the part will be anodized or painted: a mill finish that is acceptable under paint can be the wrong face for an anodized panel. Say which later process applies.
Standards such as ASTM B209 for sheet and plate, or the EN AW designation on a European drawing, are how the alloy and the temper are tied to chemistry and properties. Copy the designation. Do not translate 3003 H14 into another temper because a mill list shows both.
What naming the temper protects
Alloy without temper is half an order. The temper is what the press and the finished stiffness both depend on.
A blank that forms instead of cracking
Deep drawing and spinning want a soft or a specifically forming temper. Ordering T6 or a hard H temper for that tool is a common way to scrap the first lot.
A panel that stays flat
A hard temper holds a panel or a sign better than annealed sheet. The same alloy in O and in H14 is not one product with two labels.
A circle the tool was built around
Diameter and thickness have to match the die. A rectangle of the same alloy still has to be blanked, and the edge and the scrap are different. If the drawing says circle, quote a circle.
When sheet, coil or circles are specified
Order sheet for panels, cabinets, boat and vehicle parts, and any blank the shop will cut itself. Order coil for a continuous stamping or roll line. Order circles for cookware, lighting and other spun or deep-drawn discs. 1050 and 3003 are the alloys those circle enquiries often start from, but only when the drawing says so.
Order 5052 when the drawing wants the stronger magnesium alloy for sheet that must form and then hold. Order 6061 plate when the part will be machined or used as a structural plate in T6 or another stated T temper. Order pipe or bar on those lines, not as a note at the bottom of a sheet enquiry.
Sheet versus coil versus circles
Sheet and coil can be the same alloy and temper. The difference is delivery and who cuts the blank. Circles are sheet or coil that has already been blanked round. Comparing a circle price with a sheet price without adding the blanking is not a comparison of the same operation.
Inside the alloy list, 1100, 3003, 5052 and 6061 are not a quality ladder. 6061-T6 is stronger than 3003-H14 and much less willing to deep draw. 1050 conducts better and forms more easily than 5052, and it is the wrong choice where the drawing asks for 5052 strength. The alloy and the temper together are the comparison.
FAQ
These are the points that decide whether the first aluminum offer can go on the machine.
What does H14 mean?
It is a strain-hardened temper, about half hard, used on alloys such as 3003. It is harder and less formable than O. Use it only when the drawing says H14.
Can 6061-T6 be used for a deep-drawn pot?
Not as a substitute for a forming alloy in O or a suitable H temper. T6 is a heat-treated strength temper. Deep drawing wants a temper the die was designed for.
Is a circle just a piece of sheet?
It is a round blank. The enquiry needs diameter as well as thickness, alloy and temper. Sheet still has to be blanked before it can feed that tool.
Which standard should be copied?
The one on the drawing, for example ASTM B209 or an EN AW alloy. Do not replace it with a nearby alloy number.
What if the part will be anodized?
Say so. The incoming surface and sometimes the alloy have to suit anodizing. A mill finish chosen only for a painted part can be the wrong face.
What to send with the enquiry
State sheet, coil or circle, the alloy and temper, the standard, the thickness, the width and length or the diameter, the quantity and the surface. Add coil weight for coil. If the part is anodized or painted later, say so. The exact size is confirmed from the drawing on the enquiry.