A question from a solar-frame buyer
I'm Iris Xu, a Sales Manager in ZTRFM. A buyer in Poland asked me a fair question: "Your steel line makes purlins all day, can it just as easily make our aluminum solar frame?" The short answer is yes, but only if you respect that aluminum is a different animal. It springs back more than steel for the same bend, it scratches if you look at it wrong, and it has no zinc coating to hide surface damage.
Aluminum's elastic modulus is about 69 GPa, roughly one third of steel's 210 GPa. For a given yield strength the springback angle is larger, so the pass design has to overbend more and hold tighter tolerances on the rolls. The flip side is weight: at 2.7 grams per cubic centimetre aluminum is about one third the density of steel, which is exactly why it wins in transport and facade work.
The three series we form most
Aluminum is grouped by alloying family. On our roll forming lines the work splits across three of them.
| Series | Example grade | Tensile (MPa) | Notes for forming |
|---|---|---|---|
| 3000 (Al-Mn) | 3003-H14, 3004 | 130 to 160 | Soft, easy, general-purpose sheet |
| 5000 (Al-Mg) | 5052-H32 | 193 to 262 | Moderate strength, marine grade |
| 6000 (Al-Mg-Si) | 6061-T6, 6063-T5 | 160 to 310 | Heat-treatable, needs aging |
The 3000 series is the easy one. 3003-H14 runs about 130 to 160 MPa tensile with good elongation, and 3004 is similar with a bit more strength; both bend cleanly and are the workhorses of cookware, HVAC and general sheet. 5052-H32 is the marine choice, around 193 to 262 MPa tensile, with enough magnesium to resist seawater, which is why it shows up in trailer bodies and tank skins.
3004 deserves a mention: it is the can-stock and specialty cladding alloy, a little stronger than 3003, and it forms almost as easily, so it appears in roofing and composite-panel skins where a touch more strength helps without hurting bendability.
6000 series needs heat treatment
The 6000 series is where buyers get caught. 6061 and 6063 are heat-treatable Al-Mg-Si alloys, and their strength comes from aging, not from cold work. 6063-T5 means the profile was extruded then artificially aged; 6061-T6 means solution heat treated then artificially aged. T6 6061 reaches about 290 to 310 MPa tensile with 240 MPa yield, while 6063-T5 sits lower at roughly 160 to 200 MPa tensile but forms and anodizes more easily, which is why it dominates architectural facade and window profiles.
If you roll form 6000-series strip that has not been aged, or you weld it and let the heat-affected zone soften, the local strength can drop sharply from the base value, so the part you measure is not the part on the certificate. We always ask for the temper and, for welded assemblies, where the heat goes.
Springback is the daily fight
On a 90 degree bend in 6063-T5 you can see four to six degrees of springback, against roughly one degree in mild steel, so the last stations on an aluminum line are doing real correction work, not just shaping. We log the as-formed angle on the first sample and tune the pass before any production run. This is the single biggest difference between a steel line and an aluminum line, and it is the reason off-the-shelf steel tooling will not simply form aluminum to tolerance.
A quick word on weight: switching a steel bracket to 6063 can cut mass by roughly 60 percent for the same stiffness, which is the whole reason transport OEMs pay the premium for aluminum tooling. The saving shows up as fuel or battery-range gain over the life of the product, not just on the scale at our plant.
Surface care and lubrication
Steel gets a zinc or paint coating that hides minor roller marks. Aluminum gets nothing, so a scratched roller writes its name down the whole length of the profile. We use polished rollers and, for bright-finish work, a thin PVC film carried through the line and peeled after cutting. Lubrication matters more than people expect; a light forming oil or wax keeps the strip from picking up the roll surface and reduces the galling that leaves grey streaks.
- Polish the rollers for any visible-finish profile.
- Run PVC or paper interleave on facade and decorative parts.
- Use a compatible lubricant; dry forming of 6000 series scores easily.
- Confirm the temper before quoting springback.
Where the profiles go
The lightweight applications are the point. Solar mounting frames are almost all 6000-series extruded or roll formed sections because they span long lengths at low weight. Trailer side rails use 5052 or 6061 for the strength-to-weight gain. Facade cladding and curtain-wall trim lean on 6063 for its surface quality. None of these would make sense in steel at the same span.
One more practical note: aluminum work-hardens slowly and has no clear yield plateau, so it does not tell you when it is about to crack the way steel does. Watch the bend radius and keep it generous on 5000 and 6000 series.
Coil format and thickness range
Aluminum roll forming runs on the same coil-fed principle as steel, but the practical thickness window is narrower. We routinely form 0.4 to 3.0 mm aluminum strip, and thin 3003 cladding can go below 0.4 mm for decorative work. Coil width follows the profile: a solar frame leg might use 80 to 160 mm wide strip, while a facade panel uses 300 mm or more. Because aluminum is soft, edge wave and twist show up faster than in steel if the side guides are not set, so we pay more attention to strip tracking on these lines.
Lubricant choice
For 3000 and 5000 series a light mineral forming oil is enough. For 6000 series, especially T6 tempers that work-harden, we prefer a wax-based or polymer lubricant that leaves a thin film and washes off after forming, because dry contact scores the rolls. The lubricant also helps release the strip from the roll so the bright finish survives. Whatever you choose, tell the painter or anodizer, because residual oil changes how the surface takes coating.
Design checklist for aluminum profiles
- State the alloy and temper on the drawing, not just "aluminum."
- Keep bend radii generous; tight corners crack 5052 and 6061.
- Decide the finish early: mill, bright, anodized or painted changes roller polish and interleave.
- Flag any holes near bends so we can post-punch them.
At ZTRFM we set up dedicated aluminum lines with the right roller finish and lubrication rather than sharing a steel line, because mixing the two is how you end up with scratched solar frames. If you are specifying 3003, 5052 or 6063 for a long profile, send us the temper and the finish requirement and we will size the line and the interleave accordingly.
