What thickness of metal can be fabricated?

The short answer

Where sheet ends and plate begins

There is no single number, because the limit is not a property of the metal. It is a property of the machine that has to hold it, cut it and bend it. The practical dividing line most shops work to is about 6 mm. Below that, coil handling, turret punches and standard press brake tooling all behave normally, and the part nests comfortably on a 1,220 by 2,440 mm sheet. Above it, handling weight, cutting speed and bending tonnage start to change the economics faster than they change the geometry.

That is why a straight answer is a set of ranges rather than one figure, and why the thickness on a drawing usually selects the process before any other feature does.

Thickness range, process by process

The bands below are production ranges, not laboratory maxima. Each process can be pushed past its band, but the cost per part stops being sensible, either because cut speed collapses or because the secondary work needed afterwards removes the advantage.

Three of those bands decide most quotes. Fiber laser cutting is the default between 0.5 mm and 20 mm because nothing else combines that tolerance with that speed - a 6 kW source cuts 16 gauge mild steel at around 8,000 mm per minute. Press brake bending is usually the real constraint, not cutting: a 200 tonne brake handles roughly 6 mm across a one metre bend, 500 tonnes reaches about 10 mm, and 16 mm needs a 1,000 tonne machine. Waterjet is the escape route for anything above 25 mm or anything that must not see heat at all.

The band decides the process and the tolerance

Thickness does not only pick the machine. It also sets how much tolerance is realistic, and how much design care the feature needs. The table below is the version we use at quoting time.

Four checks before you commit a thickness

Each of these can override the one before it, which is why the order matters. Cutting is checked first because it is the cheapest thing to change.

Where the thin end breaks down

• Minimum hole size follows the thickness. As a rule the smallest practical hole diameter is about one times the material thickness, and the minimum slot width about 0.8 times. Below that the cut needs extra passes, more heat and leaves dross on the underside.
• Handling becomes the process. Below about 0.5 mm the part bends under its own weight, so the cost sits in fixtures, magnetic handling and flat packing rather than in the machine.
• Welding has a floor too. Thin walls under roughly 0.8 mm are difficult to weld without burn-through, which pushes the design towards riveting, clinching or adhesive bonding.

Where the thick end breaks down

• Edge taper appears. Laser perpendicularity stays within about one degree up to 10 mm, while plasma typically leaves a two to five degree bevel that needs grinding before a weld.
• Bend radius grows with thickness. One times the thickness is the practical minimum for mild steel, about 1.5 times for stainless, and around 2 times for 6061-T6 aluminium. Tight radii on thick stock crack on the outside of the bend.
• Tolerance loosens as thickness rises. The plus or minus 0.1 mm that is routine at 2 mm becomes plus or minus 1.5 mm at 30 mm, so features that must stay precise are usually machined after forming rather than formed.
• Long flanges stretch. Flanges grow by roughly 0.5 to 1.5 percent during forming, which shows up as a shift in hole position on long parts unless the flat pattern allows for it.

Thickness review at SOMI Custom Parts

We cut with fiber laser, plasma and waterjet, form on press brakes from 0.5 mm to 12 mm, run progressive dies from 0.3 mm to 6 mm, and weld from 0.8 mm upwards, so the thickness on your drawing is matched to a route rather than forced onto one machine. Send the drawing with an annual quantity and we will come back with the process, the flat pattern and the tolerance each feature can actually hold: see sheet metal fabrication, laser cutting, or open a project through our inquiry form.