Plasma Gases – A Practical Guide

Depending on the type of material being processed, gas selection is critical to overall efficiency. The right gas influences not only cutting speed and quality, but also consumable life and operating costs.
In this guide, we explain the combinations, characteristics, and benefits of various plasma and shielding gases.

Plasma and Shielding Gases

Gases used in plasma torches can be divided into two main groups: plasma gases and shielding gases.
Plasma gases are those used by a plasma cutter or plasma table to generate the plasma arc.
Shielding gases are used to cool, constrict, and protect the nozzle.

Argon and Hydrogen

A mixture of argon and hydrogen is an excellent choice for cutting thick sections of aluminum or stainless steel. It is not recommended for mild steel. Nitrogen is typically used as a shielding gas.
This combination delivers high-quality cuts—though at a comparatively high operating cost.

Adding nitrogen to an argon–hydrogen mixture increases performance and cut quality in high-alloy steels.

Nitrogen

Nitrogen plasma is characterized by high cutting speeds and long consumable life. It performs best on thin materials. The optimal shielding gas for nitrogen plasma is compressed air.

Using CO₂ as a secondary gas is more expensive, but improves cutting speed, cut quality, and consumable life.
An alternative shielding option for nitrogen is water, which provides excellent cut quality on aluminum and stainless steel.

In nitrogen–hydrogen mixtures, hydrogen helps reduce surface oxidation that can occur when using pure nitrogen.

Air

Atmospheric air is one of the most commonly used plasma gases. This naturally available mixture of nitrogen, oxygen, and trace gases offers excellent accessibility, low cost, and good cutting quality and speed.

Although air itself is free, it requires an appropriate compression and filtration system to ensure it is clean, dry, and free of oils and contaminants. In this configuration, air serves as both the plasma and shielding gas.

Oxygen

Oxygen plasma is ideal for cutting mild steel, delivering high cutting speeds and excellent quality. It is not recommended for aluminum or stainless steel.

Its disadvantages include relatively high cost and reduced consumable life (though modern systems have significantly minimized this issue).
Atmospheric air is typically used as the shielding gas.

Summary Table of Plasma Gases

plasma gas
shielding gas recommended use advantages / disadvantages
argon / hydrogen nitrogen
nitrogen / hydrogen		 stainless steel,
thick aluminum sections		 + excellent cut quality on materials above 127 mm
– high operating cost
nitrogen air,
CO₂,
water		 mild steel,
stainless steel,
aluminum		 + fast cutting, high quality, long consumable life
+ outstanding quality when used with water and a water table
– not recommended for thicker materials (>127 mm)
air air smild steel,
stainless steel,
aluminum		 + excellent price-to-quality ratio
– potential oxidation/nitriding of cut surfaces
oxygen air mild steel + excellent quality and high speed on thin materials
– not recommended for hard steels or aluminum
– high cost

  • Which Plasma Gases Are Used Most Often?

    The vast majority of plasma cutting system users rely on air. Its affordability, availability, and solid cutting performance make it the most common choice. A one-time investment in, for example, a screw compressor solves the supply issue and enables high-quality plasma cutting at minimal cost.

    Sources

    • Cięcie plazmowe, Linde Gas, 2019.

    • Baran, K., Cięcie plazmą. Wpływ stosowanych gazów na jakość procesu, Projektowanie i Konstrukcje Inżynierskie, 2015.

    • Illustrated Plasma Gas Selection Guide, Hypertherm, 2016.

    • Metal Production, Air Products and Chemicals Inc., 1996–2019.