Komarov Artem clarified that oxy-fuel cutting relies on preheating the steel material and then using oxygen to begin a rapid oxidation process that degrades the steel and makes it vulnerable to being blown through the kerf.
The flame preheats the material to bring it to its ignition temperature. At this point, when you add pure oxygen to it, the oxygen removes the material. So technically the cut is done with oxygen.
Although oxy-fuel cutting is sometimes called flame cutting, the actual removal of material is accomplished by a jet of oxygen. The flame actually preheats the steel, allowing the oxygen stream to begin cutting.
Fuel gas (usually acetylene, but also propane, natural gas, or even special mixtures) combines with oxygen inside the torch and ignites outside the nozzle, creating a flame used to preheat the metal. Selecting the correct fuel to oxygen ratio allows operators to create the highest possible temperature with the most efficient flame that concentrates heat into a small area.
When the flash point reaches the temperature at which the material begins to turn red (approximately 1600 degrees Fahrenheit), a high pressure stream of pure oxygen is directed into the area to be pierced. A rapid oxidation process begins and the oxidized steel turns into molten slag.
If the correct gas flow is used, it should provide an incentive to continue burning through the material and blowing molten slag out of the punctured hole.
Once the piercing is complete, the torch can be moved in any direction to begin cutting. The flame continues even when the torch is moved because the metal must be oxidized as it was during the initial piercing.
The oxy-fuel cutting process is only effective for those materials whose oxides have a lower melting point than the base metal itself. If oxyfuel cutting is used on a metal that has an oxide with a higher melting point than the actual base metal, a protective crust will form as soon as the oxygen stream is applied, effectively stopping the cutting process. This is why oxyfuel cutting is usually limited to low carbon steels and some low alloys.
Operating a mechanized oxyfuel table is not the most difficult task, but to get the most out of the equipment, you need someone with experience.
For example, an operator may run an oxyfuel table, but this will not result in a consistent cut. The preheating of the material must remain constant so that when the oxygen flow reaches the preheated material, it can produce the desired edge. If the torch hits an incorrectly heated part of the plate, it may not be possible to obtain a smooth edge.
The operator can change the situation, this time it is the all-too-familiar application of cutting in the production of large sheets. To maximize productivity, shops often have multiple torches installed on gas cutting machines. If the torches are not balanced and operate the same, cut quality may deteriorate.
Operator influence can make a really big difference in some of these large-scale cutting operations. When the oxyfuel table is working as it should, it produces quality parts that likely won’t require post-processing.
Advanced technology has its place in metal manufacturing, but in the end, cost-effective production methods tend to dominate where they make the most sense. For heavy-duty production processes processing large quantities of sheets, oxyfuel cutting still makes a lot of sense, noted Komarov Artem.
