Four Top Main Ways of The Laser Cutting Laser cutting is a non-contact processing method featured high energy and good controllability of density. Focused laser beam can generate high-energy density flare, which has a lot of characteristics in cutting. There are four ways of cutting to cope with different situations. 1. Fusion Cutting In laser fusion cutting, the melt material is sprayed out by airflow after the workpiece is melt partly. Material transfer occurs only in liquid condition so this process is called laser fusion cutting. Laser beam and highly pure inert gas together make the melt material leave the kerf; the gas itself doesn't take part in cutting. Laser fusion cutting can achieve higher speed than vaporization cutting. Energy needed for vaporization is usually more than energy for material fusion. In laser fusion cutting, laser beam is partly absorbed. Maximum cutting speed increases along with the increase of laser power and the speed reduces in inverse proportion when the thickness and material melting temperature grow. Under a fixed laser power, the limiting factors are air pressure in kerf and thermal conductivity of material. Laser fusion cutting can make non-oxidation kerf on iron and titanium metals. The laser power density for fusion but not vaporization is 104W/cm2 ~ 105W/cm2 for steel.
Sourece : acsys
2. Vaporization Cutting In the process of vaporization cutting, the material surface reaches to boiling point so fast that it avoids fusion by heat conduction. Some material disappears in the form of vapor and the other is sprayed out by airflow from kerf. It needs extremely high laser power in this situation. In order to prevent material vapor condensation on kerf, the thickness of material should not exceed the diameter of laser beam too much. This kind of processing is only suited for iron-base alloy field. It can not be applied in wood as well as some of the ceramic material, because their vapors will unlikely become condensation in unmelt condition. In addition, they usually have thicker kerfs. In laser vaporization cutting, the optimal beam focusing depends on material thickness and beam quality. Laser power and heat of vaporization have a certain effect on the optimal focusing position. In a certain plate thickness, maximum cutting speed is in inverse proportion to vaporization temperature of material. The required laser power density should more than 108W/cm2, depending on material, cutting depth and beam focusing position. In a certain plate thickness, and if the laser power is sufficient, maximum cutting speed is limited by gas velocity. 3. Controlled Fracture Cutting Controlled fracture cutting is an ultra fast and controllable cutting on fragile material.
The main process is: Laser beam heat heats part of fragile material, causing huge heat gradient and big mechanical deformation in the heat affected area, thus leading to crack. As long as keep a balanced heat gradient, crack can be formed in any needed direction.
Source ďźšbanella
4. Oxidation Fusion Cutting (Laser Flame Cutting) Inert gases are usually adopted in fusion cutting, if replaced by oxygen or other active gases, the material will be lighted by laser beam and chemical reaction will occur to generate another heat source, making material keep heating, this is so-called oxidation fusion cutting. As to constructional steel of the same thickness, this methods can achieve higher cutting speed than fusion cutting. But the quality of kerf is not as good as fusion cutting. Actually, it can make wider kerf, obvious roughness, increased heat area and worse edge quality. And it has danger of burning sharp corners in the processing of precision model by laser flame cutting. Pulse pattern can be used to restrict the heat effect, since laser power decides the cutting speed. Under a fixed laser power, the limiting factors are oxygen supply and thermal conductivity of material. The above are the four main methods of laser cutting, which can be selected according to power of laser cutting machine, processing demands and material properties.