What Metals Can Be Cut with the Oxy-Fuel Gas Process?

Oxy-fuel cutting is a powerful thermal cutting process used to cut ferrous metals. This highly popular metal-cutting method uses oxygen and fuel gases (such as propane, acetylene, propylene, MAPP, and natural gas) to cut through materials.
Also called ‘plasma cutting’, oxy fuelled cutting is one of the most widely used industrial thermal cutting processes. It can cut materials with thicknesses from 0.5 mm to 250 mm, and the cutting equipment is relatively low cost, available in both manual and mechanised form.

How Does Oxy Fuelled Cutting Work?

The cutting process is fairly simple. A mix of oxygen and the chosen fuel gas is used to preheat the metal to its ‘ignition temperature’ but well below its melting point. The ignition temperature can differ depending on the kind of metal; for example, steel is 700°C to 900°C.
Next, a jet of pure oxygen is applied into the preheated area, which sets off a strong exothermic chemical reaction between the oxygen and the metal, forming by-products consisting of iron oxide or slag. The cutting oxygen blows away the slag enabling the oxygen jet to penetrate through the material and continue to cut through it.

Metals You Can Cut with Oxy-Fuel Cutting

Electrically conductive ferrous metals are typically used in the oxy-fuel process. Some examples are:
• Low carbon steel
• Mild steel
• Medium carbon steel
• Hardened low carbon steel
• Iron
• Titanium
When cutting steel, it’s important to note that only certain types of steel can be cut. For example, carbon steel or mild steel ranging from a low carbon content (less than 0.3% carbon) to a medium carbon content (0.3 to 0.6% carbon) work well with oxy-fuel cutting – but others do not.

Metals You Can’t Cut with the Oxy-Fuel Cutting Method

Generally, non-ferrous metals and any corrosion-resistant metals are not suitable for oxy-fuel cutting. This is because of how the oxy-fuelled cutting process works; it oxidises the heated metal before blasting that oxidised metal away with pure oxygen, therefore making a cut as the gas flows through the material. As such, if the metal can’t oxidise (which means rusting), it cannot be cut using oxy-fuelled cutting.

Metals unsuited for oxy-fuelled cutting include:

  • Cast iron
  • Stainless steel
  • Aluminium
  • Copper
  • High carbon steel

Basic Requirements for Oxy-Fuel Cutting:

  • Primarily, the purity of the oxygen stream determines the cutting speed and cut-edge quality. As a result, the cutting torch and nozzle design must be high quality since they play a huge role in protecting the oxygen flow from air entrainment.
  • Oxygen purity should be at least 99.5%. Even a 1% decrease in purity can reduce the cutting speed by 25% and could increase gas consumption by 25%.
  • The material’s ignition temperature must be lower than its melting point; if not, the material would melt and flow away before any cutting takes place.
  • The oxide melting point needs to be lower than the surrounding material’s so that the oxygen jet can blow it away successfully.
  • The oxidation reaction between the metal and the oxygen jet must remain sufficient throughout in order to maintain the ignition temperature.
  • Gaseous reaction products should be kept at a minimum to prevent dilution of the cutting oxygen

Get in Touch Today

We at KERF are industry experts in oxy-fuel, plasma cutting and waterjet cutting technology, processes and materials.
If you need assistance with equipment or materials purchase, have questions, or are here for our world-class after-sales support, please don’t hesitate to contact us today – our knowledgeable and friendly team is just a phone call or email away.

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