Carbon steel / iron cutting

Carbon steel, iron, or mild steel — what's the difference?

In everyday Georgian, "რკინა" (iron), "ფოლადი" (steel) and "შავი ლითონი" (black metal) are used almost interchangeably, but none of them names a separate material. Technically, carbon steel is an alloy of iron (Fe) and carbon that, unlike stainless, contains no chromium and has no corrosion resistance. The "black" name refers to the dark mill-scale layer left on the sheet after hot rolling, clearly visible even on raw, uncut stock. So "iron cutting" and "steel cutting" describe the same job. If the part is destined for a damp environment and you do not plan to paint it, carbon steel is the wrong choice — that calls for stainless (inox).

• Iron / iron cutting — everyday term
• Steel — general technical term
• Carbon steel / mild steel — the precise material name
• Stainless / inox / nerzhaveika — a different, chromium-bearing metal

What thickness of carbon steel (iron) do we cut?

Sheet from 0.5–3mm cuts fast and economically — the most common range for nameplates, signage and decorative parts. From 4–10mm, cutting time and therefore cost rise, because the laser needs more power and a slower pass. 10mm is the real ceiling for our machine; anything thicker requires a different process. The manufacturable minimum hole diameter depends on the metal grade, thickness, geometry and particular equipment. Specify the required size in the drawing; the team confirms feasibility after reviewing the file. Minimum order is 1 piece. Specify the required tolerance in the drawing; achievable tolerance and edge finishing are confirmed for the material, thickness and geometry.

Why does the cut edge go dark — the physics of oxygen-assisted cutting

When cutting carbon steel we add oxygen as the assist gas alongside the laser beam: it reacts exothermically with the heated metal and helps the laser cut quickly even through thick sheet. That same reaction coats the cut edge in a thin layer of iron oxide, giving it a dark, sometimes brownish-blue tint. This is a normal physical result, not a defect, and it does not affect the strength of the part. We cut stainless and aluminum with nitrogen instead, so their edges come out noticeably cleaner and lighter — one of the main practical differences between the materials. Where the edge will be visible, light grinding removes the oxide layer easily.

What do we make from carbon steel?

Carbon steel is chosen where price and strength matter more than the raw surface appearance — the aesthetics are handled afterward with paint or powder coating. We regularly cut carbon steel for door and office nameplates, mounting and support brackets, ornamental mangals (BBQ grills), decorative panels and partitions, and structural parts. If the piece will stand outdoors or in a damp space, uncoated carbon steel will rust over time, so we recommend a zinc or paint layer.

When is plasma cutting or a partner workshop the better answer?

Our laser CNC cuts carbon steel cleanly and accurately up to 10mm, but on heavier structural plate a laser stops being the rational tool and plasma cutting becomes more efficient. We do not own plasma equipment: those jobs we either run through a vetted partner workshop or point you directly to the right shop. We also have no guillotine, press brake, lathe or milling machine — we cannot produce bent or turned parts, though we will advise which stage to give to whom. In practice, almost every nameplate, sign, decorative or bracket job falls within the 10mm range.