Oxyfuel Cutting: Principles and Process

Oxyfuel Cutting

Introduction to Oxyfuel Cutting

Oxyfuel cutting, also known as flame cutting or burning, is a process that uses a flame produced by a torch to cut through metals, primarily ferrous metals. The process relies on the chemical reaction of oxidation (rusting) to separate the metal.

• Oxyfuel Cutting (OFC): A thermal cutting process that uses fuel gases and oxygen to cut metals.

• Oxidation: The chemical reaction where a metal reacts with oxygen, often producing heat and metal oxides.

Types of Metals

• Ferrous Metals: Metals that contain iron. These metals can oxidize (rust) and are suitable for oxyfuel cutting.

• Examples: Mild steel, cast iron.

• Nonferrous Metals: Metals that do not contain significant amounts of iron and do not oxidize in the same way. These are generally not suitable for oxyfuel cutting.

• Examples: Aluminum, stainless steel, brass.

Oxyfuel Cutting Process

The cutting process involves several steps to ensure the metal is properly heated and oxidized for cutting:

1. Crack the fuel gas: Open the fuel gas valve on the torch slightly.

2. Ignition: Light the fuel gas with a striker to produce a flame.

3. Add oxygen: Gradually introduce oxygen until the desired flame is achieved.

4. Heating: Heat the metal until it reaches its ignition temperature, turning cherry red.

5. Cutting oxygen: Activate the oxygen jet, which delivers a concentrated stream of oxygen to the heated area. This causes rapid oxidation (burning) of the metal, producing heat and molten metal (dross).

• Key Reaction: The process relies on the exothermic reaction of iron with oxygen: $4Fe + 3O_2 \rightarrow 2Fe_2O_3$

• Additional info: The oxygen jet not only oxidizes the metal but also blows away the molten oxide (dross) from the cut.

Key Terms in Oxyfuel Cutting

• Dross (Slag): The molten metal and oxide that is expelled from the cut. It is also called slag.

• Kerf: The width of the cut made by the oxyfuel torch, including the material removed and the dross that comes out.

Comparison of Ferrous and Nonferrous Metals in Oxyfuel Cutting

Metal Type	Contains Iron?	Can be Cut by Oxyfuel?	Example
Ferrous	Yes	Yes	Mild steel
Nonferrous	No	No	Aluminum, Brass

Summary

• Oxyfuel cutting is effective for ferrous metals due to their ability to oxidize rapidly.

• Nonferrous metals do not oxidize in the same way and are not suitable for this process.

• The process involves heating, oxidation, and removal of molten metal (dross) to achieve a clean cut.