Principle of Laser-Oxyfuel Hybrid Cutting Machine

Laser flame composite cutting usually refers to “laser oxygen cutting”, which is one of the main laser cutting processes (the other two are laser melting cutting and laser vaporization cutting). It does not mean “laser-generated flame,” but rather a hybrid process that uses a laser as a heat source, supplemented by pure oxygen as an assist gas, to initiate a vigorous oxidation combustion reaction (i.e., “flame”) in metals (mainly steel materials) during the cutting process. This process leverages the thermal energy from the chemical reaction to significantly enhance cutting performance.

Next, we will explain its principle in detail from several perspectives:

Core Principle: Laser-Induced Controlled Metal Combustion

1. The role of the laser (ignition and maintenance):

• A high-energy-density laser beam is focused onto the workpiece surface, causing the temperature of the irradiated metal to rapidly rise to its ignition point (approximately 1350°C for iron).
• The laser beam provides a continuous, precise, high-energy heat source that not only ignites the reaction, but more importantly maintains the reaction area at a high temperature.

2. Role of oxygen (combustion agent and scavenger):

• A 1 stream of high-pressure, high-purity oxygen is coaxially injected with the laser beam onto the metal spot heated by the laser.
• The iron (Fe) that reaches the ignition point and oxygen (O₂) undergo a violent oxidation exothermic reaction (combustion):4Fe 3O₂ → 2Fe2O, heat
• This reaction releases a lot of heat (about 3-5 times the energy of the laser itself!), This is the key to “compound” energy. This additional heat greatly enhances the overall melting/gasification capacity.

3. Composite collaborative process:

• Preheating and ignition: The laser first heats the local metal to the ignition point.
• Combustion exothermic: oxygen injection, the metal burns violently, generating much higher heat than the laser itself can provide, rapidly melting or even oxidizing the metal, and forming slag (mainly Feo and Fe3o4).
• Blowing and forming: Another important role of high-pressure oxygen gas flow is to blow the molten metal oxide (slag) generated by the reaction from the cutting seam violently like an “air knife” to form a clean, relatively smooth cutting surface.

Continuous: The laser beam moves in front, continuously preheats the new area, and the combustion reaction follows the laser focus forward and downward, and finally penetrates the workpiece and forms a cut.

How is this “compound” approach so efficient? (Advantage)

1. Strong ability to cut thick plates: For carbon steel (such as low carbon steel), laser oxygen cutting is the most cost-effective and fastest method for cutting medium and thick plates (usually more than 6mm, up to 30mm or even thicker). Pure laser melting cutting (such as with nitrogen) needs to rely entirely on laser energy to melt the metal, the face of thick plate appears to be inadequate.

2. Fast cutting speed: due to the addition of chemical energy of metal combustion reaction, the total energy input is much higher than that of a single laser energy, so the cutting speed is significantly faster than the melting cutting under the same power.

3. Equipment power requirements are relatively low: to cut the same carbon steel, the laser power required for laser oxygen cutting can be much lower than that of pure laser melting cutting, reducing equipment costs and energy consumption.

4. Good cutting quality: For carbon steel thick plates, a cutting surface with good verticality and less slag (ideal state) can be obtained.

Process characteristics and limitations

1. Material selectivity:

• Primarily for reactive metals: The most typical and ideal application material is carbon steel.

• Not suitable for stainless steel, aluminum, copper, etc:
• Stainless steel: chromium (Cr) and other elements will form high melting point oxides (such as Cr2O3), which hinder the oxidation reaction from continuing, and the slag is not easy to blow away, resulting in rough cutting surface and serious slag hanging.
• Aluminum and copper: the melting point of its oxides (Al2O3,CuO) is much higher than that of the substrate itself, covering the surface like a hard shell, preventing the reaction from continuing, and having high reflectivity to laser.

2. Characteristics of cutting surface:

• Due to the oxidation reaction, the surface of the cut will have an oxide layer (similar to the bluing treatment) and may be slightly rough (compared to the bright side of the nitrogen cut).
• There may be a slight slag hanging at the bottom, which needs to be minimized by optimizing the process parameters.

3. The heat affected zone is larger: the violent oxidation reaction will generate more heat, resulting in the heat affected zone of the workpiece being wider than that of laser melting and cutting, and the overall thermal deformation of the workpiece may be slightly larger.

Comparison with other cutting processes

VS. Pure laser nitrogen cutting (melting cutting):

• Nitrogen cutting: by laser melting metal, blowing away the melt with high pressure nitrogen. No oxidation reaction, the section is bright and no oxide layer, but the speed is slow, the gas consumption is large, and the cost is high. It is suitable for stainless steel, aluminum, etc., and it is not economical for thick carbon steel.
• Oxygen cutting: oxidation reaction addition, fast speed, low cost, suitable for carbon steel, but the section has an oxide layer.

VS. Traditional flame cutting (oxyacetylene cutting):

• Traditional flame: by flame preheating, pure oxygen combustion cutting. Slow preheating, wide slit, low precision and large thermal deformation.
• Laser oxygen cutting: with high-energy laser precision, fast preheating, cutting seam is very narrow (and laser spot diameter), high precision, sma
• ll slope, small thermal impact, is the traditional flame cutting modernization, high precision upgrade version.

Summary

The core principle of the laser flame composite (laser oxygen) cutting machine is to use a high-energy laser beam to accurately ignite and maintain the violent combustion reaction of metal (iron) in a pure oxygen environment, and combine the thermal energy of the laser with the chemical energy of metal oxidation to achieve “1 1>2″ cutting effect. It perfectly combines the advantages of high precision and high focus of laser with the advantages of high efficiency and low cost of oxygen combustion, making it an irreplaceable mainstream process in the field of medium and thick carbon steel sheet cutting.