Oxy-fuel cutting is an economical and effective method for thick carbon steel plates; however, achieving a quality cut requires setting the correct parameters based on material thickness. Variables such as gas pressure, cutting speed, nozzle selection, and preheat time all change with thickness. In this article, we look at parameter and speed settings by material thickness in CNC oxy-fuel cutting.
The Principle of Oxy-Fuel Cutting
Oxy-fuel cutting works by heating steel to its ignition temperature and then oxidizing it with a high-purity oxygen jet. This chemical reaction cuts the material by burning it rather than melting it, which is why the method is only effective on oxidizable materials such as carbon steel.
Gas Pressure Settings by Material Thickness
Cutting oxygen pressure should be increased as material thickness increases; thin plates (10-20 mm) require lower pressure, while thick materials (above 50 mm) need higher pressure to ensure the jet reaches full depth throughout the cut. Insufficient pressure can cause incomplete cutting (uncut marks at the bottom), while excessive pressure can create irregularities on the cut edge.
Cutting Speed and Its Relation to Thickness
Cutting speed is inversely proportional to material thickness: as thickness increases, speed must be reduced. Cutting too fast causes a leaning cut front and failure to achieve full penetration, while cutting too slow causes excessive dross buildup and a wider heat-affected zone. Reference speed tables published by equipment manufacturers by thickness serve as a starting point, with fine-tuning done on-site.
Nozzle Selection and Sizing by Thickness
Nozzle diameter and type are selected based on the thickness of the material being cut; small-diameter nozzles provide a narrow, precise cut on thin materials, while larger-diameter nozzles supply the oxygen flow needed for full-depth cutting on thick materials. Incorrect nozzle selection reduces cut quality and unnecessarily increases gas consumption.
Preheat Time and Flame Settings
Before cutting begins, the material is preheated to reach its ignition temperature; this time increases with thickness. Insufficient preheating can cause the cut to start improperly. Flame settings (oxygen-to-fuel gas ratio) are also optimized by thickness to ensure both a proper start and consistent cutting throughout the cut.
Other Parameters Affecting Cut Quality
Nozzle height (distance to material surface), cutting path precision, and surface cleanliness of the material also directly affect cut quality. On rusty or dirty surfaces, cutting start can be delayed or irregular; a surface check before cutting is therefore recommended.
DMK Makina's Oxy-Fuel Cutting Process
Based in Lüleburgaz and serving customers across the Thrace and Marmara regions, DMK Makina provides CNC oxy-fuel cutting for thick carbon steel parts; gas pressure, speed, and nozzle selection are optimized for each project based on material thickness.
Conclusion
Setting the correct parameters based on material thickness in CNC oxy-fuel cutting directly affects both cut quality and production efficiency. Optimizing gas pressure, cutting speed, and nozzle selection together delivers consistent, high-quality cut results.
