Laser cutting is a precise and efficient manufacturing process that uses an invisible light beam to cut through materials, offering numerous benefits over traditional mechanical cutting methods. With its high accuracy, fast cutting speed, and ability to cut complex shapes, laser cutting is gradually replacing traditional metal cutting techniques.
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Composition of Laser Cutting Equipment
A laser cutting machine consists of several key components, including the laser generator, beam delivery system, numerical control motion system, automatic focusing cutting head, worktable, and high-pressure gas supply system. Various parameters affect the laser cutting process, some of which depend on the technical performance of the laser generator and machine, while others are variable.
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Key Parameters of Laser Cutting
To achieve optimal cutting results, it's essential to understand the following key parameters:
1. Beam Mode
The beam mode, also known as the Gaussian mode, is the ideal mode for cutting, typically found in low-power laser generators (<1 kW). Multi-mode, a mixture of high-order modes, has lower cutting ability and focusability compared to single-mode lasers.
| Table. 1 single-mode laser cutting process parameters of common materials | |||||
| Material | Thickness (mm) | Auxiliary gas | Cutting speed (cm/min) | Slit width (mm) | Laser power (w) |
| Low carbon steel | 3 | O2 | 60 | 0.2 | 250 |
| Stainless Pan | 1 | O2 | 150 | 0.1 | 250 |
| Titanium alloy | 10(40) | O2 | 280(50) | 1.50(3.5) | 250 |
| Organic transparent glass | 10 | N2 | 80 | 0.7 | 250 |
| Alumina | 1 | O2 | 300 | 0.1 | 250 |
| Polyester carpet | 10 | N2 | 260 | 0.5 | 250 |
| Cotton fabric (multi-ply) | 15 | N2 | 90 | 0.5 | 250 |
| Cardboard | 0.5 | N2 | 300 | 0.4 | 250 |
| Corrugated cardboard | 8 | N2 | 300 | 0.4 | 250 |
| Quartz glass | 1.9 | O2 | 60 | 0.2 | 250 |
| Polypropylene | 5.5 | N2 | 70 | 0.5 | 250 |
| Polystyrene | 3.2 | N2 | 420 | 0.4 | 250 |
| Hard polyvinyl chloride | 7 | N2 | 120 | 0.5 | 250 |
| Fiber reinforced plastics | 3 | N2 | 60 | 0.3 | 250 |
| Wood (plywood) | 18 | N2 | 20 | 0.7 | 250 |
| Low carbon steel | 1 | N2 | 450 | 中 | 500 |
| 3 | N2 | 150 | --- | 500 | |
| 6 | N2 | 50 | 0.15 | 500 | |
| 1.2 | O2 | 600 | 0.15 | 500 | |
| 2 | O2 | 400 | 0.20 | 500 | |
| 3 | O2 | 250 | --- | 500 | |
| Stainless Steel | 1 | O2 | 300 | --- | 500 |
| 3 | O2 | 120 | --- | 500 | |
| Plywood | 18 | N2 | 350 | --- | 500 |
| Table. 2 multi-mode laser cutting parameters of common materials | ||||
| Materials | Plate thickness (mm) | Cutting speed (cm/min) | Slit width (mm) | Laser power (kw) |
| Aluminium | 12 | 230 | 1 | 15 |
| Carbon Steel | 6 | 230 | 1 | 15 |
| Stainless steel (0Cr18Ni9) | 4.6 | 130 | 2 | 20 |
| Boron/epoxy composite | 8 | 165 | 1 | 15 |
| Fiber/epoxy composites | 12 | 460 | 0.6 | 20 |
| Plywood | 25.4 | 150 | 1.5 | 8 |
| Plexiglass | 25.4 | 150 | 1.5 | 8 |
| Glass | 9.4 | 150 | 1 | 20 |
| Concrete | 38 | 5 | 6 | 8 |
2. Laser Power
The required laser power depends on the material being cut, material thickness, and cutting speed requirements. Laser power significantly affects cutting thickness, speed, and kerf width. Generally, increasing laser power allows for thicker materials to be cut, faster cutting speeds, and wider kerf widths.
3. Focus Position
The focus position has a significant impact on kerf width. Typically, the focus is set at approximately 1/3 of the material thickness below the surface, resulting in the maximum cutting depth and minimum kerf width.
4. Focal Length
When cutting thick steel plates, a longer focal length is recommended to achieve a high-quality, vertical cutting surface. A longer focal length results in a larger beam diameter, reducing power density and cutting speed. To maintain a consistent cutting speed, increasing laser power is necessary. For cutting thin plates, a shorter focal length is preferred, resulting in a smaller beam diameter, higher power density, and faster cutting speed.
5. Assist Gas
Oxygen is commonly used as the assist gas when cutting low-carbon steel, as it utilizes the iron-oxygen combustion reaction to enhance the cutting process, resulting in faster cutting speeds and high-quality cuts. The pressure of the assist gas affects the cutting process, with higher pressures increasing the kinetic energy and slag removal capabilities.
6. Nozzle Structure
The nozzle structure and orifice size also impact laser cutting quality and efficiency. Different cutting requirements necessitate the use of different nozzles. Common nozzle shapes include circular, conical, and rectangular shapes. Laser cutting typically employs coaxial (gas flow and light axis aligned) blowing, and controlling the distance between the nozzle exit and workpiece surface (0.5-2.0 mm) ensures a stable cutting process.
| Table. 3 examples of laser cutting process parameters of common metal materials |
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| Material | Thickness mm | Auxiliary gas | Cutting speed cm/min | Laser power kW |
| Low Carbon Steel | 1 | O2 | 900 | 1000 |
| 1.5 | 300 | 300 | ||
| 3 | 200 | 300 | ||
| 6 | 100 | 1000 | ||
| 16.2 | 114 | 4000 | ||
| 35 | 50 | 4000 | ||
| 30CrMnSi | 1 | 200 | 500 | |
| 3 | 120 | 500 | ||
| 6 | 50 | 500 | ||
| Stainless Steel | 0.5 | 450 | 250 | |
| 1 | 800 | 1000 | ||
| 1.6 | 456 | 1000 | ||
| 3.2 | 180 | 500 | ||
| 4.8 | 400 | 2000 | ||
| 6 | 80 | 1000 | ||
| 6.3 | 150 | 2000 | ||
| 12 | 40 | 2000 | ||
| Titanium alloy | 3 | 1300 | 250 | |
| 8 | 300 | 250 | ||
| 10 | 280 | 250 | ||
| 40 | 50 | 250 | ||
