Laser Cutting Thickness Guide: How Thick Can You Cut?

One of the most common questions we receive at QuickCut is: "How thick can you cut?" It's a practical question with a practical answer — but the details matter. Laser cutting thickness limits depend on the material, the machine's power, and what you actually need from the finished part. This guide walks through the maximum and minimum thicknesses available for each material, how thickness affects price, cut speed and edge quality, and how to choose the right thickness for your project.

Laser Cutting Thickness Limits by Material

At QuickCut we use high-power fibre lasers, which are the gold standard for cutting sheet metal. Fibre lasers offer excellent beam quality, fast cutting speeds on thin material, and the ability to push into thicker sections that older CO₂ machines couldn't handle reliably.

Here's a summary of the thicknesses available across our materials:

Material	Minimum thickness	Maximum thickness	Sweet spot
Mild steel (S235 / S355)	0.5 mm	20 mm	1–10 mm
Stainless steel (304 / 316)	0.5 mm	12 mm	1–6 mm
Aluminium (5052 / 6061)	0.8 mm	10 mm	1.5–6 mm
Galvanised steel	0.5 mm	3 mm	0.8–2 mm
Checker plate (mild steel)	2 mm	6 mm	3 mm

How Thickness Affects Laser Cutting Price

Thickness is one of the biggest cost drivers in laser cutting. There are two ways it pushes up the price: cutting speed and material weight.

Cutting speed

A fibre laser cuts thin sheet at very high speed — for example, 1.5 mm mild steel might be cut at 10–15 metres per minute. At 10 mm, that same machine may only manage 1–2 metres per minute. The machine time per metre of cut increases dramatically, and since pricing is partly based on machine time, thicker parts cost more even if the geometry is identical.

Material weight and cost

Thicker sheet metal is heavier and more expensive per square metre. A 6 mm mild steel sheet weighs roughly three times as much as a 2 mm sheet of the same area. Because material is priced by weight or by sheet, doubling the thickness roughly doubles the raw material cost of your part — before you even consider the added machine time.

Assist gas consumption

Laser cutting uses a pressurised assist gas — usually oxygen for mild steel and nitrogen for stainless and aluminium — to blow the molten material out of the cut kerf. Thick material requires more gas at higher pressure, which adds a modest but real cost to very thick sections.

How Thickness Affects Laser Cutting Edge Quality

Edge quality is about more than aesthetics — it directly affects whether parts will fit together cleanly, whether they need secondary operations, and whether they're safe to handle. Thickness has a significant impact on what the cut edge looks and feels like.

Thin sheet (0.5–3 mm)

At the thin end, fibre lasers produce exceptionally clean edges with minimal burr and a very fine striation pattern. Parts cut from 1–3 mm mild steel typically require no secondary finishing for most applications. The heat-affected zone (HAZ) is narrow, and dimensional accuracy is at its best — tolerances of ±0.1–0.2 mm are achievable. See our laser cutting tolerances guide for a full breakdown of what accuracy you can expect.

Mid-range sheet (4–8 mm)

In the 4–8 mm range, you'll notice slightly more pronounced striations on the cut face — the characteristic diagonal lines left by the laser beam as it travels. The HAZ is wider, and some parts may have a small burr on the underside that can be removed with a deburring tool. For structural applications this is rarely a problem. For precision assemblies, light grinding or filing of mating surfaces is sometimes worthwhile.

Heavy plate (10–20 mm)

Above 10 mm, the laser is working hard and the cut characteristics change noticeably. Striations become more pronounced, and the cut face may taper slightly — a phenomenon called "drag" where the bottom of the cut lags slightly behind the top. The HAZ is wider, and for mild steel cut with oxygen, some surface oxidation is normal. Parts in this thickness range frequently require deburring and may benefit from light grinding if they're joining to other machined components.

For most structural and general engineering applications, heavy plate cuts are perfectly adequate. For precision fits, it's worth discussing tolerances with your fabricator before committing to very thick laser-cut parts — or considering plasma cutting, which can sometimes offer better economics above 15 mm at the cost of slightly wider kerfs.

Choosing the Right Thickness for Your Project

Here's a practical decision framework for picking thickness in South Africa:

1. Start with the structural requirement. How much load does the part need to carry? What deflection or stress is acceptable? Engineering calculations or rule-of-thumb industry standards (e.g. 3 mm for general enclosures, 5–6 mm for brackets under moderate load) are your first filter.
2. Check standard stock thicknesses for your chosen material. Ordering from standard stock avoids surcharges and delays. In South Africa, 3 mm mild steel is the most widely stocked thickness — it's a good default for general fabrication.
3. Consider the downstream operations. Will the part be bent, welded, powder coated or anodised? Bending is easier on thinner material; welding can compensate for thinner sections; anodising and powder coating cover both thin and thick equally well.
4. Upload your DXF and get an instant price at different thicknesses. QuickCut's pricing tool makes it trivial to compare — upload once, get a price for 3 mm, then change the thickness and get another. There's no cost to quote and no minimum order.
5. Review the quoted price and lead time, and make a value decision. Sometimes the difference between 4 mm and 5 mm is small; sometimes it's significant. Knowing the actual numbers helps.

Laser Cutting vs Plasma Cutting: Does Thickness Change the Answer?

Below 12 mm, fibre laser cutting is almost always the right choice for sheet metal in South Africa. It's faster, more accurate, and produces a better edge than plasma at equivalent thicknesses. Above 12 mm, the economics start to shift. Plasma cutting is faster and cheaper per metre on very heavy plate (16–25 mm), though at the cost of a wider kerf (3–5 mm vs 0.1–0.3 mm for laser) and a rougher edge that usually requires grinding.

For most South African engineers and fabricators, if your design can be executed in under 12 mm mild steel or under 6 mm stainless or aluminium, fibre laser is the better process. It's what QuickCut uses, and it's what our instant pricing tool is built around.

Minimum Feature Size vs Thickness

Thickness doesn't just affect the cut edge — it also constrains the minimum feature size you can reliably cut. A 20 mm slot is no problem in 1 mm steel, but a 1 mm slot in 20 mm steel is essentially impossible. A useful rule of thumb: minimum slot width should be at least equal to the material thickness. Minimum hole diameter should ideally be at least 1.2× the material thickness. Going smaller than these limits risks the laser burning out the web between features or producing overheated, distorted cuts.

For thin materials (1–3 mm), you have a lot of geometric freedom. For heavy plate, design constraints become significant. If you're unsure whether your features are manufacturable, the DXF preparation guide covers the design rules in detail.

Frequently Asked Questions