The answer to "which method should I use to cut this plate?" largely comes down to a single variable: thickness. Laser, plasma and oxy-fuel cutting each dominate in a different thickness range. In this article, we explain which method takes over at which thickness, and where oxy-fuel cutting stands out.

Thickness: The Main Factor That Determines the Method

Every thermal cutting method delivers its most efficient result within a certain thickness range. Once you step outside that range, either quality drops or cost rises quickly. That's why the right method selection almost always starts with thickness.

Thin to Medium Thickness: Laser

For plates up to roughly 20-25 mm, fiber laser is generally the best choice thanks to its high precision, clean edge and speed. In thin-gauge work it also largely eliminates the need for secondary processing.

Medium-to-Thick Range: Plasma

For medium and thick plate, when speed and cost become the priority, plasma cutting takes over. While it doesn't produce as sharp an edge as laser, it offers an economical and fast balance for thicker material.

Very Thick Plate: Oxy-Fuel

As thickness increases further (generally above roughly 25-30 mm, and considerably thicker), oxy-fuel cutting becomes the most sensible method. Oxy-fuel cutting can economically cut carbon steel even at thicknesses of 100 mm and above. This is because the process relies on a controlled combustion reaction rather than electrical power; as thickness increases, cost rises far more slowly compared to laser or plasma.

Is Thickness the Only Factor? Other Considerations

  • Material type: Oxy-fuel cutting only works on carbon and low-alloy steels; it cannot be used on stainless steel or aluminum.
  • Tolerance: If tight tolerances are required, laser is the answer; if a wider tolerance is acceptable, oxy-fuel is suitable for thick work.
  • Quantity and cost: For thick, high-volume jobs, the unit cost of oxy-fuel cutting is advantageous.

A Closer Look at the Thickness Bands

To put rough numbers on it: fiber laser systems in common industrial use today handle carbon steel up to roughly 25-30 mm comfortably, with some high-power machines pushing further; plasma systems typically perform best from about 6 mm up to 50-80 mm depending on amperage; and oxy-fuel cutting takes over anywhere from about 20-25 mm upward, with no real practical upper limit for carbon steel — plate several hundred millimeters thick can still be cut economically. These bands overlap deliberately, because in the overlap zone, tolerance, edge finish and total cost — not thickness alone — decide which method wins.

Where the Crossover Decision Actually Gets Made

In the 20-30 mm range, all three methods are technically capable of producing a usable part, which is exactly why this band causes the most indecision. The right call usually comes down to a simple question: does the downstream process (welding, machining, assembly) need a tight, laser-grade edge, or can it tolerate the wider kerf and rougher surface of plasma or oxy-fuel? If the part will be machined afterward anyway, spending extra for laser-level precision on the initial cut is often unnecessary cost.

Summary: Which Method for Which Thickness?

In short: laser for thin work, plasma for medium thickness, oxy-fuel for very thick carbon steel plate. In the boundary zones, the choice is made based on the balance between tolerance, material and cost. At DMK Makina, we help you make this call before cutting begins, based on your drawing, material grade and the tolerance your application actually requires — so you don't pay for precision you don't need, or sacrifice precision you do.