The working principle of fiber laser cutting machines can be divided into the following core links, integrating technologies such as laser generation, beam transmission, material cutting and precise control:
I. Laser Generation and Excitation
Rare earth doped optical fiber excitation
Fiber lasers use quartz fibers doped with rare earth elements (such as ytterbium Yb³⁺) as the medium, and inject energy through a semiconductor pump source (with a wavelength of 915nm or 976nm) to transition rare earth ions to a high-energy state. Photons reflect multiple times in a resonant cavity with high reflectivity, forming stimulated radiation, and eventually output a high-energy laser beam with a wavelength of 1070nm.
Laser characteristics
The output laser features single-mode/multi-mode beams (M²≤1.1), with a power range of 500W- 20,000W, and an electro-optical conversion efficiency as high as 30%-35%, far exceeding the 10% of traditional CO₂ lasers.
Ii. Beam Transmission and Focusing
Optical fiber flexible transmission
The laser is transmitted to the cutting head through low-loss quartz optical fiber (loss ≤0.2dB/km), and the beam divergence Angle (≤0.1mrad) is optimized by using the optical fiber coupler to achieve long-distance lossless light guiding.
High-precision focusing system
The internal focusing lens of the cutting head (such as the F-theta lens) focuses the light beam into a spot with a diameter of approximately 0.1mm, and the energy density is as high as 10⁶-10⁷ W/cm². The automatic focusing system dynamically adjusts the focus position accuracy (±0.2mm) to adapt to different material thicknesses.
Iii. Material Cutting Mechanism
Energy absorption and thermal effect
The focused laser beam instantly heats the surface of the material to the melting point or vaporization point (such as 1500℃ for steel and 660℃ for aluminum), and cutting is achieved in three ways:
Melting cutting: Auxiliary gas (such as nitrogen) is used to blow away the molten metal, which is suitable for stainless steel.
Oxidation cutting: Oxygen reacts with high-temperature metals to release additional heat, which is used for carbon steel.
Vaporization cutting: High-power direct vaporization of materials, suitable for non-metallic thin plates.
Cutting parameter optimization
Power, speed, focus position and gas pressure need to match the material properties. For example, when cutting 1mm stainless steel, the speed can reach 30m/min, and the oxygen pressure is usually 0.5-1.5MPa.
Iv. Intelligent Control System
Numerical control and motion control
The CAD drawings were analyzed and the G-code was generated by using systems such as Siemens 840D. The servo motor (positioning accuracy ±0.02mm) was driven to control the movement of the X/Y/Z axes. Combined with visual positioning (accuracy ±0.05mm), the cutting path was automatically calibrated.
Adaptive adjustment
Real-time monitoring of material thickness and defects, dynamic adjustment of power and speed to ensure stable cutting quality.
V. Auxiliary Systems and Advantages
Gas assistance and dust removal
Coaxial nozzles spray auxiliary gas (O₂/N₂) to remove slag, and the vacuum cleaning system regularly cleans the dust inside the equipment.
Comparison of core advantages
Compared with CO₂ lasers: energy consumption is 80% lower, cutting speed is twice as fast, and maintenance-free reflective lenses.
Compared with YAG lasers: The speed is 4 to 5 times higher and the photoelectric efficiency is 10 times higher.
Application scenarios
It is suitable for the precision processing of metal plates (such as stainless steel, aluminum alloy, etc.) and is widely used in fields such as automotive manufacturing (body parts), aerospace (titanium alloy components), and electronic devices (micro-holes in mobile phone frames).
Through the integration of the above technologies, the fiber laser cutting machine has achieved "non-contact processing", with the cut width controllable within 0.1-0.2mm, an extremely small heat-affected zone, and no need for molds, significantly enhancing production flexibility.
