Laser cutting is a thermal processing technology based on the precise separation achieved through the interaction of a high-energy laser beam and materials.Its core principle lies in the controlled conversion of light and heat energy, causing the localized material of the workpiece to rapidly melt, vaporize, or reach its ignition point. With the aid of an auxiliary gas flow, the molten or vaporized material is removed, thus forming a continuous and clean kerf. This technology integrates knowledge from multiple disciplines such as optics, thermodynamics, materials science, and automatic control, enabling high-precision, high-speed cutting of both metallic and non-metallic materials.
Laser generation originates from the principle of stimulated emission. In a laser, the working medium (such as optical fiber, CO₂ gas, or solid crystal) undergoes population inversion under the excitation of a pump source, forming a gain region. When photons propagate back and forth within the resonant cavity and induce the emission of more photons of the same frequency, phase, and direction, a high-brightness, highly directional, and highly coherent laser beam is generated. After being shaped and focused by an optical system, the laser beam can be compressed into an extremely fine spot with a diameter of tens to hundreds of micrometers, thus creating an extremely high energy density on the workpiece surface.
During the cutting process, the focused laser beam is projected vertically or obliquely onto the material surface. The light energy is rapidly converted into heat energy, causing the temperature of the affected area to rise to the material's melting point or even boiling point in a very short time. Under these conditions, the metallic material melts or vaporizes, and some materials also undergo chemical reactions with the assist gas (such as the exothermic oxidation of carbon steel in an oxygen atmosphere), further enhancing the energy input. The assist gas (commonly oxygen, nitrogen, or compressed air) is ejected at high speed through a coaxial nozzle. This serves two purposes: firstly, it blows away the molten or vaporized material from the kerf, preventing slag from re-condensing at the cut; secondly, it provides additional chemical energy in an oxidizing gas environment, increasing the cutting rate.
The cutting quality and efficiency depend on the coordinated matching of laser power, beam quality, focal point position, cutting speed, and the type and pressure of the assist gas. Power determines the total energy input per unit time, while velocity affects the duration of energy interaction with the material; both jointly control the heat input to the kerf. The focal point position influences the spot size and energy density distribution, thus determining the cutting penetration and cross-sectional morphology. The momentum of the auxiliary gas removes slag and forms a protective atmosphere, preventing oxidation, discoloration, or cut contamination.
The entire processing is precisely controlled by a CNC system, which precisely controls the laser head's trajectory and process parameters, achieving high-precision tracking of complex two-dimensional or three-dimensional contours. Modern laser cutting equipment can also incorporate sensors to monitor focal point shift, power fluctuations, and gas pressure changes in real time, using closed-loop control for timely correction and ensuring consistency in batch processing.
In summary, the working principle of laser cutting is based on a high-energy-density laser beam as the core driving force. Through multi-field coupling of light, heat, and force, it achieves rapid, localized material removal and completes high-precision shaping under intelligent control. This principle endows laser cutting with broad material adaptability and excellent processing flexibility, making it irreplaceable in high-end manufacturing, precision instruments, and large-scale customized production.
