Gas cutting is a technology with a long tradition that is constantly being improved and developed. Oxygen cutting is one of the most popular methods used for processing steel, most often low-alloy and low-carbon steels. It is also used for cutting metal sheets covered with corrosion or in packages. Gas cutting process is used where there is a need to cut steel of considerable thickness, maintaining precise results and high efficiency.
Oxygen cutting – technology characteristics
Process of this type of cutting consists in heating the surface of the processed material to the ignition temperature. The next step is to supply oxygen under high pressure. For correct cutting results, the cleanliness of the cut should be at least 99.5%. As a result of these two actions, the processed material is oxidized and blown out of the fracture. The heat of combustion is generated and heats the deeper layer to the ignition temperature. The rest of the process takes place internally to cut the workpiece as a result. In order to properly carry out the gas cutting process, a specially designed torch that mixes fuel gas with oxygen, should be used.
Oxygen cutting is not appropriate for machining some materials. This is caused by the flash point. In the case of pure iron, it is 1050°C. When we try to treat steel with 1.5% carbon admixture, the temperature rises to 1380°C. Therefore, gas cutting works well for cutting low-carbon and low-alloy structural steels.
Oxygen cutting in action. What kind of gases are used?
Fuel gas used to generate the flame has also great importance for the cutting process. The most commonly used gases are acetylene, propane and natural gas. Oxy-acetylene cutting enables very high temperatures to be achieved in a short time. Economical customers choose the oxy-propane cutting method because when fast heating is not needed, it allow to save some money.
Heating flame is responsible for:
- elimination of contamination from the surface of the material being cut. A clean surface of the processed material is essential for the proper conduct of the gas cutting process
- guaranteeing the metal temperature appropriate to initiate the process (over 1050°C)
- providing the thermal energy needed to sustain the cutting process
- creating a protective atmosphere for the oxygen stream so that no air enters it
Oxygen cutting process in details
The heating flame is positioned 5-10 mm above the cut sheet. The top surface of the sheet reaches its flash point, the torch rises as the glow exits, then the cutting oxygen valve opens and piercing begins.
The cutting process begins when the lower surface of the sheet is cut and the gap is blown through. The width of the cutting gap depends on the thickness of the material. The thicker the material, the greater the gap width.
Successful cutting is determined by the selection of the correct parameters: gas pressure, machine feed and torch settings.
Advantages and disadvantages of oxygen cutting
- a very large range of thicknesses of cut materials
- possibility of cutting at different angles
- economic method
- long piercing time due to preheating
- wide heat-affected zone
- narrow range of cut materials
There are several advantages to using gas technology. First and foremost, it is the most economical method of thermal cutting that can cut a wide range of material thicknesses. The investment and operating costs are relatively low compared to other technologies. Considering the processing of metals with really high thickness, the quality of the cut is very good. In addition, gas cutting is possible at various angles, while maintaining perpendicular edges.
Operation of an oxygen cutting machine - do you need a trained specialist?
Oxygen cutting machines are technologically advanced CNC cutting machines. In order to fully use their potential, the user should know not only the basic instructions and the principle of operation. It is worth supporting the work with the device with the knowledge gained during training sessions dedicated to operators and technologists.