With the downstream development of the optoelectronics industry, the application fields of optoelectronics are receiving increasing attention. Optoelectronics magazines focus on nine major application areas: information communication/information processing and storage, consumer electronics, advanced manufacturing, national defense and security, semiconductor processing, energy, sensing and test measurement, lighting and display, and medical applications.
As early as the 1970s, lasers were first used for cutting. When a focused laser beam hits a workpiece, the irradiated area rapidly heats up, causing the material to melt or vaporize. Once the laser beam penetrates the workpiece, the cutting process begins: the laser beam moves along the contour line while melting the material. This is laser cutting!
Laser Cutting Process Parameters
Laser cutting technology is a processing method that uses a high-energy-density laser beam to precisely cut materials. It is widely used in the processing of both metallic and non-metallic materials, with the most common equipment being laser cutting machines.
The main process parameters for laser cutting include laser power, cutting speed, cutting thickness, and gas flow rate. Other factors such as laser beam quality, lens focal length, defocus amount, and nozzle also significantly affect laser cutting.
1. Laser Power
Laser power is one of the most important parameters of a laser cutting machine. Higher power enables faster cutting speeds and the ability to cut thicker materials.
Generally, laser power refers to the power of the laser source.
For material properties, if the surface reflectivity is high, more laser energy will be reflected rather than absorbed for cutting. Therefore, higher laser power is needed to ensure sufficient energy for cutting. Similarly, if the material has good thermal conductivity, the heat generated by laser irradiation will quickly dissipate inside the material, making it difficult to raise the temperature of the cutting area to the level required for cutting. In this case, increasing laser power is also necessary to improve cutting efficiency.
Additionally, cutting materials with high melting points requires higher laser power and power density.
2. Cutting Speed
Under a certain power condition, as the plate thickness increases, the laser beam needs to penetrate deeper material layers to complete the cut. Research shows that the relationship between cutting speed and kerf surface roughness is not a simple linear relationship but shows a U-shaped trend. This means there is an optimal cutting speed point for different material thicknesses and gas pressure conditions. Cutting at this speed minimizes the roughness of the kerf surface, resulting in the smoothest cut.
Generally, faster cutting speeds require higher power.
Cutting speed refers to the length a laser cutting machine can cut per minute; faster speeds mean higher efficiency. The cutting speed depends on the material type, thickness, hardness, and is also affected by laser power and spot diameter.
3. Cutting Thickness
Cutting thickness refers to the maximum thickness of material a laser cutting machine can cut. Factors affecting cutting thickness include:
Equipment Power: Higher power generally allows for cutting thicker materials.
Material Type: Different materials have different hardness, density, and toughness, affecting the achievable cutting thickness.
Cutting Technology: Different cutting technologies (e.g., laser, waterjet, plasma) have different maximum cutting thicknesses.
Cutting Process Parameters: Parameters such as cutting speed and gas pressure also affect cutting thickness.
4. Gas Pressure
During the fusion cutting process, the laser beam heats the material to its melting temperature. The assist gas then blows away the molten metal to form the kerf. The gas pressure must be high enough to effectively remove the molten metal, ensuring continuous cutting and a clear kerf.
Gas flow rate is also related to the nozzle type; different nozzle shapes affect gas distribution and flow characteristics, requiring different gas flow rates for optimal performance.
5. Laser Beam
The beam mode output by the laser is crucial for cutting quality. Experimental studies show that during non-oxygen-assisted cutting, the kerf width is nearly equal to the laser spot diameter. The spot size is proportional to the focal length of the focusing lens: longer focal length results in a larger spot, while shorter focal length results in a smaller spot.
However, while a short focal length lens can achieve a smaller spot, its depth of focus is also reduced. A smaller depth of focus imposes stricter requirements on the distance between the workpiece surface and the lens. The defocus amount significantly affects cutting speed and depth and must be kept constant during the cutting process. Typically, a negative defocus amount is used, meaning the focus position is set below the plate surface.
6. Nozzle
The nozzle is a critical component affecting laser cutting quality and efficiency. Laser cutting typically uses coaxial nozzles (where the gas flow is concentric with the optical axis). The nozzle outlet diameter should be selected based on the thickness of the material being cut. Additionally, the distance from the nozzle to the workpiece surface significantly impacts cutting quality. To ensure a stable cutting process, this distance must remain constant.
Strategies for Improving Laser Cutting Technology
In practical applications of laser cutting technology, improving cutting efficiency, quality, and reducing costs are common considerations. Improving laser cutting technology to enhance production efficiency, cutting quality, and reduce costs can be approached from the following aspects:
Higher Power Lasers: With advances in laser technology, using higher-power lasers can significantly increase cutting speed while reducing the heat-affected zone and material deformation, making cutting more efficient and of higher quality, especially for thicker materials.
Optimizing Process Parameter Combinations: Systematically adjust parameters such as laser power, cutting speed, assist gas type and pressure, and nozzle-to-material distance. Fine-tune these settings based on specific material and cutting requirements, and find the optimal parameter combination through repeated trials to improve cutting efficiency and quality.
Auto-Focus Systems: Use auto-focus systems to automatically adjust the laser focus position based on material thickness and type, ensuring cutting precision.
Reducing Non-Cutting Time: Quickly move the cutting head to the next cutting start point to improve overall operational efficiency.
Automatic Detection and Path Adjustment: Automatically detect material edges and tilt angles, and automatically adjust the cutting path to reduce material waste and pre-processing time.
Nesting Software Optimization: Use nesting software for simulation cutting, plan the most concise cutting path, reduce empty travel, and improve material utilization and cutting speed.
Regular Maintenance: Regularly maintain and service the laser cutting machine, such as replacing wear parts, cleaning optical components, and calibrating equipment, to ensure long-term stable operation and maintain optimal cutting performance.
Maintain a Clean Work Environment: Keep the laser cutting machine's working environment clean, with suitable temperature and moderate humidity, to avoid the impact of dust and excessive humidity on the equipment and cutting results.
Adopt Advanced Control Systems: Use more advanced control systems and software to improve control precision and response speed, supporting more complex cutting tasks.
Monitor New Technological Advances: Continuously monitor new advances in laser technology, such as more efficient laser sources, more advanced optical systems, and intelligent software algorithms, to continuously improve cutting capabilities.
