Laser cutting technology is no stranger to most people. It is a processing method that uses high-energy laser beams to precisely cut materials. Widely applied in the processing of both metallic and non-metallic materials, common equipment includes laser cutting machines.
Key Parameters of Laser Cutting
The primary parameters in laser cutting include laser power, cutting speed, material thickness, and gas flow. Other factors, such as beam quality, lens focal length, defocusing amount, and nozzle design, also significantly impact cutting performance.
1. Laser Power
Laser power is one of the most critical parameters of a laser cutting machine. Higher power increases cutting speed and allows for thicker materials to be processed. Generally, laser power refers to the power of the laser source.
For materials with high surface reflectivity, more energy is reflected rather than absorbed during cutting, requiring higher laser power. Similarly, materials with good thermal conductivity quickly dissipate heat, making it difficult to achieve the high temperatures needed for cutting, thus necessitating increased laser power. Materials with high melting points also demand higher laser power to reach the necessary melting or vaporization temperatures.
2. Cutting Speed
At a given power, cutting speed decreases as material thickness increases, as the laser beam must penetrate deeper layers. Research shows that the relationship between cutting speed and surface roughness is not linear but exhibits a U-shaped trend. For each material thickness and gas pressure, there exists an optimal cutting speed that minimizes surface roughness and ensures smooth edges.
Cutting speed refers to the length the laser cutting machine can cut per minute. It depends on the material type, thickness, and hardness, as well as laser power and beam diameter.
3. Cutting Thickness
Cutting thickness refers to the maximum material thickness a laser cutting machine can process. Factors influencing cutting thickness include:
Equipment Power: Higher power supports greater cutting thickness.
Material Type: Different materials have varying hardness, density, and toughness, affecting thickness.
Cutting Technology: Techniques like laser, water jet, or plasma cutting have different limits.
Process Parameters: Factors such as cutting speed and gas pressure also influence thickness.
4. Gas Pressure
In melt cutting, the laser beam heats the material to its melting point, and gas removes molten metal to create the cut. Gas pressure must be sufficient to clear the molten metal effectively, ensuring continuity and clarity of the cut. The type and flow of gas are influenced by the nozzle design, requiring optimization based on the material and cutting requirements.
5. Laser Beam
The beam quality of the laser significantly affects cutting results. Research indicates that, in oxygen-free cutting, the kerf width closely matches the laser spot diameter. Spot size is proportional to the focal length of the lens—shorter focal lengths produce smaller spots but also reduce focal depth. During cutting, maintaining a consistent defocus value (usually negative) is crucial to achieving optimal speed and depth.
6. Nozzles
Nozzles play a vital role in laser cutting quality and efficiency. Coaxial nozzles (where the gas flow aligns with the optical axis) are commonly used. Nozzle diameter should match material thickness. Additionally, the distance between the nozzle and workpiece must remain constant to ensure process stability.
Evaluating Laser Cutting Quality
While laser cutting of metals is well-known, not everyone understands how to evaluate the quality of the process. Common criteria include edge surface roughness, bottom burrs, and kerf width.
1. Edge Surface Roughness
During cutting, airflow and feed speed create vertical (or inclined) striations on the edge surface. Deeper striations indicate rougher surfaces, while shallower ones result in smoother edges. Surface roughness affects appearance and friction properties, so minimizing roughness indicates higher cutting quality. Adjusting laser power, speed, focal length, gas type, and pressure can optimize roughness.
2. Bottom Burrs
Laser cutting vaporizes metal using high energy, with auxiliary gas blowing away the molten slag. However, mismatched parameters like material thickness, insufficient gas pressure, or improper feed speed can cause slag to cool and form burrs on the bottom. Removing burrs adds extra labor, making this a critical quality indicator.
3. Kerf Width
Kerf width reflects machining precision. While it doesn't usually impact cutting quality, it becomes crucial for intricate designs requiring minimal diameter cuts. Narrower kerfs allow for more precise profiles, which is a significant advantage of laser cutting over plasma cutting.
Strategies for Improving Laser Cutting Applications
Enhancing efficiency, quality, and reducing costs are ongoing objectives in laser cutting. Key improvement strategies include:
Higher-Powered Lasers: Advanced lasers can increase speed and minimize heat-affected zones, especially for thicker materials.
Optimized Parameters: Adjusting power, speed, gas type, pressure, and nozzle distance based on material type ensures the best results.
Auto-Focus Systems: Automatically adjusting focal points improves cutting precision for varying material thicknesses.
Reduced Non-Cutting Time: Faster head movements between cuts enhance overall efficiency.
Edge Detection: Automatic alignment reduces material waste and preparation time.
Nesting Software: Simulated cutting paths maximize material utilization and minimize travel.
Regular Maintenance: Cleaning optics, replacing worn parts, and calibrating equipment ensure consistent performance.
Controlled Environment: Maintaining cleanliness, optimal temperature, and humidity prevents equipment degradation.
Advanced Control Systems: Upgraded software supports more complex tasks with higher precision.
Adopting New Technologies: Stay updated on advancements in laser sources, optics, and algorithms to maintain cutting-edge capabilities.
