Laser cutting is a precision machining technique, and its effectiveness is influenced by several factors. To achieve high-quality cutting results with a laser cutting machine, careful consideration of the following key elements is necessary:
- Beam Mode:
The beam mode is a significant factor affecting the cutting performance of a laser cutting machine. The fundamental mode, also known as the Gaussian mode, is the ideal mode for cutting, typically found in lower power (less than 1kW) lasers. Multimode, on the other hand, is a mixture of multiple higher-order modes. Compared to the fundamental mode, multimode has poorer focusing performance and lower cutting ability. Therefore, a single-mode laser in a laser cutting machine excels in both cutting capability and cutting quality compared to a multimode laser.
- Laser Power:
Laser power is a critical parameter determining the cutting capability of a laser cutting machine. The required laser power mainly depends on the type of material being cut, its thickness, and the desired cutting speed. Generally, the greater the laser power, the greater the thickness of the material that can be cut, and the faster the cutting speed. However, the width of the cut will also increase accordingly.
- Focal Point Position:
The focal point position significantly affects the cut width in laser cutting machine applications. Typically, setting the focal point approximately 1/3 of the material thickness below the surface results in the maximum cutting depth and minimum cut width.
- Focal Length:
The choice of focal length depends on the thickness of the material being cut by the laser cutting machine. When cutting thicker steel plates, a longer focal length beam should be selected to ensure good perpendicularity of the cut surface. However, a longer focal length leads to an increased focal depth, a larger spot diameter, and a decrease in power density, which reduces the cutting speed. To maintain a certain cutting speed, it is necessary to increase the laser power accordingly. Conversely, when cutting thin plates with a laser cutting machine, a shorter focal length beam is preferred, as this results in a smaller spot diameter and higher power density, thereby increasing the cutting speed.
- Assist Gas:
Assist gas plays an important role in the laser cutting process. When cutting mild steel with a laser cutting machine, oxygen is often used as an assist gas to utilize the heat generated by the iron-oxygen combustion reaction to promote the cutting process. Oxygen not only increases the cutting speed but also improves the cut quality and reduces dross formation. The pressure of the assist gas also affects the cutting effect; higher pressure can enhance slag removal. The specific gas pressure needs to be adjusted according to factors such as the material, plate thickness, cutting speed, and cut surface quality when using a laser cutting machine.
- Nozzle Structure:
The structural shape and outlet size of the nozzle also affect the quality and efficiency of laser cutting. Different cutting requirements require different nozzles for the laser cutting machine. Common nozzle shapes include cylindrical, conical, and square. Laser cutting typically employs a coaxial blowing method (where the gas flow is concentric with the optical axis). If the gas flow is not coaxial with the optical axis, a large amount of spatter is likely to occur during cutting. To ensure the stability of the cutting process with a laser cutting machine, the distance between the nozzle end face and the workpiece surface should be controlled, typically between 0.5 and 2.0mm, to facilitate smooth cutting.