Aluminum Sheet Metal Fabrication

Aluminum is chosen for weight, for heat and for the fact that it does not rust — but it behaves differently on every machine in the shop, and most of the problems in aluminum work come from a drawing written as if the material were steel. This page covers the alloys we run, how cutting and bending have to be planned differently, and what we finish in-house versus what is routed out.

Which alloy, and why it decides the route

If the part is bent or welded, 5052 or 5754 is usually the safer default. If it carries load or needs machining after forming, 6061 is worth its extra cost — but the bend radii have to be designed for it. Tell us the function and we will say which way we would go.

What changes because the material is aluminum

Laser cutting

Aluminium reflects the laser beam and conducts heat away quickly, so it cuts differently from steel: we cut it with nitrogen, which avoids the oxide edge that oxygen cutting leaves and keeps the cut face clean enough to go straight to bending. Our three laser cutters — two 3,000 W and one 6,000 W — cut aluminum from 0.5 mm to 10 mm. Reflectivity also means the cutting programme matters more than on steel, and we keep it on file so a repeat order matches the first one.

Bending

Aluminium springback is roughly twice that of mild steel, and heat-treated 6061-T6 will crack if the inside radius is taken below the material’s limit. Two consequences follow for the drawing: bend radii must be stated rather than left to the shop, and bend reliefs at the end of flanges save the crack that shows up three parts into a run. Our four CNC press brakes are rated 250 tonnes with a 3,000 mm bed, so a full-width panel can be formed in one setup. On visible parts we use protective film or urethane tooling to keep the surface free of press marks.

Welding and distortion

Aluminium conducts heat away from the weld pool about five times faster than steel, so joints need more heat input and more care to avoid distortion. Welding 6061 also softens the heat-affected zone, which is why a welded 6061 bracket is not as strong as the drawing’s alloy note suggests. We weld at ten stations in the same building as cutting and bending, jigged and sequenced to hold flatness, and we will tell you when a redesign — a bend instead of a weld, or a change of alloy — is cheaper than welding it.

Finishing aluminum

• Brushing and mirror polishing run in our own workshop. Grain direction and grit sequence are agreed against a sample panel before production, which matters more on aluminum than on steel because the same grit reads differently on a softer surface.
• Anodizing goes to audited applicators. We specify the class and the film thickness on the drawing — Type II sulfuric anodizing typically 10–25 micrometres, Type III hard anodizing where wear resistance is the point — agree the colour reference before the batch runs, and check the result on receipt. Hard anodizing grows the film roughly half into the metal and half out of it, so dimensions on tightly toleranced features have to be planned at the drawing stage, not corrected afterwards.
• Chromate or chrome-free conversion coating is used where the part has to stay conductive or be painted, and is routed the same way.
• Powder coating, where a colour is wanted, is applied on partner lines that we specify and inspect.

One practical note worth putting on the drawing: aluminum that has been anodized is electrically insulating on the treated surface. If the part needs an earth bond or a conductive contact face, those areas must be masked or machined after finishing, and the note belongs on the drawing rather than being discovered at assembly.

What to put on the drawing

• Alloy and temper (5052-H32, 5754, 6061-T6 and so on)
• Bend radii where the part is formed, especially on 6061
• Finish: brushed (grain direction and grit), anodized (class and film thickness), conversion coated, or powder coated to an RAL reference
• Areas that must stay conductive, must be masked, or are cosmetic faces
• Whether the part is load-bearing, so alloy selection is not left to the shop floor
• Inspection document requirements — mill certificates, first-article report, or your own format

How we inspect and what travels with the shipment

Batches are checked against the drawing revision we quoted. Measuring equipment is height gauges and coating thickness gauges — we do not have a coordinate measuring machine, and we say so rather than claiming measurements we cannot take. Material certificates matched to the sheet we cut, a first-article report, and in-process and outgoing inspection records travel with the batch. Our quality system is documented to ISO 9001; we do not hold a third-party ISO 9001 certificate, and the audit references we can offer for review under NDA are TUV Rheinland MIC-ASI243729 and Bureau Veritas MIC-ASR263630.

Lead time and what we need to quote

• Simple samples: 3–7 days. Complex first article: 15–20 days. Production batch: 25–35 days.
• Tooling is quoted separately: 7–15 days simple, 30–45 days complex. Tooling is not included in sample time.
• Quotations are issued after drawing review, not from a price list.

Send 2D drawings (PDF, DWG or DXF) and 3D models (STEP, IGES or SolidWorks) with quantity, alloy, finish and destination. We will come back with a quotation, the DFM points we would change, and a straight answer on which steps run in our building and which are routed out.

Anodizing is the finish most aluminum enclosures end up in, and most of what goes wrong with it is decided before the part reaches the bath. The alloy, the weld filler, the rack contact point and the colour fastness are all covered on the stainless and aluminum enclosure finishes page, along with what to write on the drawing.

Related reading: surface treatment for aluminum · anodizing aluminum sheet metal · aluminum bending best practices · metal surface finishing · anodized aluminum enclosures · transport and rail enclosures