What Materials Cannot Be Cut with Plasma Cutting?

Plasma cutting processes evolved from plasma welding in the 1960s; today, they’re a highly effective and efficient method of cutting conductive metals. Given the scope of plasma cutters available as well as their capacity to slice through most metals, these tools are commonplace in any metal fabrication shop, no matter the size.

While they’re widespread across industry and home workshops, plasma cutters do have limits – from the gas type needed to the materials they cannot cut. These variables, as well as how the machinery works, will be discussed below.

How Does a Plasma Cutting Machine Work?

A plasma metal cutting machine cuts through conductive materials via a plasma torch – specifically electrically conductive metal. The plasma cutter cut is cleaner than many alternative methods, including oxy-fuel cutting.

Most mechanical metal cutting methods shear or burn the metal, which is the case with oxy-fuel cutting. However, plasma cutting machinery melts the metal with high-velocity ionized gas. The machine sends an electrical arc through the gas, which passes through a constricted opening and creates a clean, precise cut. The gas then blows away the molten metal from the cut, producing a smooth edge.

Types of Plasma Cutter

Plasma cutters come in different forms; for example, portable handheld machines, combination units with a plasma cutter, a stick, and a TIG welder, and also those with built-in compressors. CNC plasma cutting machines are also available, with “CNC” standing for “computer numerical control”. These high-tech cutters employ a computer to control and direct an accelerated hot plasma at the electrically conductive metal, slicing through it accurately.

Typically, most types of plasma cutters can easily cut metals ranging from 1-2mm to 1-2 inches thick – any more than that, and it gets a little tricker. Metals that plasma cutters can cut include:

  • Mild steel
  • Stainless steel
  • Carbon steel
  • Expanded steel
  • Copper
  • Aluminum
  • Brass

Still, no matter the type of plasma cutting tool, there are some materials it cannot cut – or, if it can, gas selection must be considered.

Gas Selection

Compressed air typically isn’t enough; depending on the metal thickness, specific gases are needed to produce higher temperatures of ion plasma for cutting through certain kinds of metal.

When cutting thicker materials, like thick aluminium, for instance, argon and hydrogen gas mixtures are normally used, while thin stainless steel would need nitrogen and methane. For mild steel and carbon steel cutting, pure oxygen via oxy-fuel cutting is ideal.

The Materials That Plasma Cutters Don’t Cut

Given how they work, along with their cutting power and precision, plasma cutters sound like the ultimate replacement for cutting all materials. Unfortunately, it’s not time to throw away the old trusty saw.

Plasma cutting machinery cannot cut:

  • Glass
  • Concrete
  • ceramics
  • wood
  • plastic

A plasma cutting machine requires conductivity to complete the electrical circuit; otherwise, it cannot do its job. Because the above materials aren’t conductive metals, plasma cutters can’t slice through them.

Furthermore, these units cannot cut non-electrically conductive metal. Many metals are poor electrical conductors or simply too problematic to deal with and thus cannot be cut using plasma metal cutting processes. Some of these challenging metals include:

  • Lead – this metal splatters from the heat, which is messy but also dangerous
  • Tin – this material is notoriously difficult to cut and often entails poor results
  • Tungsten – this metal is the hardest to cut and requires intensive professional gear
  • Manganese – this material has the same conductivity properties as ceramics (poor)

Other rarer materials that plasma cutting tools cannot cut include the following:

  • Bismuth
  • Thallium
  • Gallium
  • Indium
  • Ununpentium
  • Ununquadium
  • Ununhexium
  • Ununtrium

Do You Need a Plasma Cutter?

Various plasma cutter types with different capacities are suited to certain metals and tasks. If you’re unsure which plasma-cutting tool you require, please contact us today. Our friendly team can use their specialist industry knowledge to help you select the right plasma cutter for your needs.

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