🔩 ALUMINUM
Aluminum Sheet Metal Fabrication: Grades, Bend Radii, and Forming Realities
Aluminum is the default sheet metal for anyone who needs strength without weight, but the grade you pick decides whether a part bends clean or cracks on the brake. The gap between a forming-friendly 5052 panel and a 7075-T6 bracket that splits at the bend line is the single most expensive lesson in aluminum fabrication. Buyers on ManufacturingBase filter shops by the exact temper and gauge they need so the formability is matched before the first hit.
ISO 9001AS9100ITAR
Why temper, not just alloy, governs the bend
The first thing experienced fabricators check on an aluminum drawing is the temper, because it changes the part more than the alloy designation does. 5052-H32 is the workhorse of formed aluminum sheet: roughly 195 MPa tensile, excellent ductility, and it will take a tight bend radius equal to its own thickness or less without cracking. It also resists marine and atmospheric corrosion better than the heat-treatable grades, which is why enclosures, fuel tanks, and chassis pans live in 5052.
6061-T6 is the opposite trade. You get 310 MPa tensile and machinability that holds a crisp edge, but the T6 temper is hard and notch-sensitive, so a 90-degree bend wants a generous inside radius of at least one to one-and-a-half times material thickness, often more on heavier gauge. Bend it sharper and you get orange-peel surface texture followed by hairline cracking on the outside fiber. Smart shops bend 6061 in the T4 condition and age to T6 afterward when the geometry is aggressive, or they simply specify 5052 if forming dominates the part.
7075-T73 and 2024 push the strength further still, 7075 toward 505 MPa, but both are essentially un-formable in their high tempers. They are flatwork and machined-feature alloys in the sheet world, not parts you fold on a press brake. When a print calls for a 7075 bent bracket, the honest answer is usually that it should be bent in the annealed (O) or W condition and heat treated after, or redesigned as a machined or riveted assembly.
Cutting, punching, and the burr question
Aluminum laser-cuts fast but reflectively. Modern fiber lasers handle it well up to about 12 mm, though thin gauge under 1 mm can show dross on the underside if assist-gas pressure and nitrogen purity are not dialed in. CO2 lasers struggle with aluminum's reflectivity and are largely retired for this work. For high-volume thin-gauge parts, turret punching or CNC punch-and-form is often cheaper per piece and gives you louvers, embosses, and countersinks in the same setup.
Waterjet is the go-to when you cannot tolerate any heat-affected zone, for example on 2024 or 7075 where edge metallurgy matters for fatigue. It is slower and leaves a slightly tapered edge, but the cut metal is unchanged. Burrs are the recurring headache: soft aluminum smears rather than shears cleanly, so deburring, edge-breaking, and sometimes vibratory tumbling are standard secondary ops that you should price into every quote rather than discovering them at inspection.
Finishing: anodize, chromate, and what the alloy allows
Finish selection has to respect the alloy chemistry. 6061 and 5052 anodize beautifully and predictably, giving clear or dyed Type II coatings and hard Type III coatings for wear surfaces. The high-copper alloys, 2024 and to a lesser extent 7075, anodize to a darker, less uniform color because the copper disrupts the oxide layer, so cosmetic anodize on 2024 is rarely a good spec.
For corrosion protection without the look, chromate conversion coating (MIL-DTL-5541, formerly Alodine) is the aerospace standard and is conductive, which matters for grounding and EMI. Powder coat and wet paint both adhere well over a chromate or anodize pretreatment. The pitfall to avoid is bending after anodizing: the hard oxide is brittle and will craze at the bend, so the sequence is always form first, finish last.
Tolerances you can actually hold on a brake
Flat-pattern features cut by laser or punch hold tight, typically +/- 0.13 mm on hole position and edge dimensions. The looseness enters at the bend. A single press-brake bend carries roughly +/- 0.25 mm of dimensional variation and +/- 0.5 to 1 degree of angle, and that stacks with every additional bend across the part. Springback compounds it: the harder the temper, the more the part opens back up after the punch lifts, so 6061-T6 needs more overbend than soft 5052.
The practical rule is to design tight tolerances onto flat, laser-cut features and keep bent-feature tolerances generous, ideally +/- 0.4 mm or looser between bends. If you genuinely need a bent dimension held to a few thousandths, that is a signal to machine the feature, use a forming die rather than air bending, or add a secondary machining op after forming, all of which cost more and should be discussed up front.
Frequently Asked Questions
For anything with bends, default to 5052-H32. It forms to a bend radius at or below its own thickness, resists corrosion without coating, and welds cleanly, which covers the majority of enclosures, brackets, and panels. Step up to 6061-T6 only when you need the extra strength or a machined edge and your bends are gentle (inside radius at least equal to thickness). Avoid 7075-T73 and 2024 for formed parts entirely; in their normal tempers they crack on the brake. Those two belong in flatwork, machined fittings, or parts formed in the annealed condition and heat treated afterward. As a quick cost note, 5052 and 6061 sheet run roughly the same per pound and are widely stocked in gauges from 0.5 mm to 6 mm, while 7075 and 2024 cost 2 to 3 times more and have longer lead times because they are aerospace-stocked rather than commodity items.
Plan on a minimum inside bend radius of about 1 times material thickness for thin 6061-T6 and 1.5 to 2 times thickness as you get into 3 mm and heavier. The T6 temper is strong but notch-sensitive, so bending sharper than that produces orange-peel texture on the outside of the bend followed by cracking. If your design truly needs a sharper corner, the options are: specify the material in T4 temper, bend it, then artificially age to T6; switch to 5052-H32, which tolerates radii at or below 1T; or bottom-bend in a die rather than air-bend to reduce cracking. Always orient the bend line across the grain (perpendicular to the rolling direction) when you can, because aluminum cracks more readily when bent parallel to grain. Tell your fabricator the grain direction matters and they will nest the flat pattern accordingly, though it can reduce material yield and add a few percent to cost.
Yes, and 5052 and 6061 both weld well with TIG or pulsed MIG using 4043 or 5356 filler. 5052 is the more weld-friendly of the two and resists cracking. The catch with 6061 is heat-affected-zone softening: welding locally anneals the T6 temper, dropping strength in the weld zone by 30 to 40 percent unless the part is re-solution-treated and aged afterward, which is rarely practical on a fabricated assembly. Design welded 6061 joints away from highly loaded areas, or use 5052 where weld strength matters more than base strength. 2024 and 7075 are generally considered non-weldable by fusion methods because they crack; they are joined by rivets or fasteners instead. Expect TIG aluminum welding to run roughly 80 to 130 USD per hour in North America, and budget for post-weld straightening because thin aluminum distorts heavily from weld heat.
For common 5052 and 6061 gauges that shops stock, a straightforward laser-cut-and-bend part runs 5 to 10 business days at prototype quantities and 2 to 3 weeks for production lots in the hundreds. Add a few days for anodizing or chromate, since those go to an outside plating house and batch up. The schedule stretches when the alloy is exotic: 7075-T73 and 2024 are not on most shops' racks, so you wait on a mill or distributor order, often pushing lead time to 3 to 5 weeks. Expedite is possible on standard grades, sometimes 48 to 72 hours for simple flat-and-bend work, but it carries a 25 to 50 percent rush premium. The biggest schedule killers are tight bent-feature tolerances that force secondary machining and cosmetic anodize specs that require rework if the surface comes back blemished.
Last updated: July 2026
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