Laser cutting is a high-precision, high-efficiency cutting technology widely used in the processing of various materials, including metals and non-metals. This article will detail the principles, operation methods, and key technical points of laser cutting.
I. The Principle of Laser Cutting
Laser generation
The basic principle of laser cutting is to use a high-power-density laser beam to irradiate the surface of a material, causing the material to melt, vaporize, or burn rapidly, thereby achieving the cutting purpose. Laser generation requires a laser device. A laser device mainly consists of three parts: a pump source, a gain medium, and an optical resonant cavity. The pump source provides energy to the gain medium, which absorbs the energy and generates stimulated emission. The optical resonant cavity then amplifies and shapes the stimulated emission, ultimately forming a high-power-density laser beam.
Laser-material interaction
When a laser beam strikes a material surface, various physical phenomena occur, including reflection, absorption, scattering, and heat conduction. The key to laser cutting lies in the sufficiently high energy density of the laser beam to rapidly bring the material surface to its melting or boiling point, thus achieving cutting. The interaction between laser and material mainly includes the following aspects:
(1) Heat conduction: When a laser beam irradiates the surface of a material, the surface temperature rises rapidly. Heat is transferred to the interior of the material through heat conduction, forming a heat-affected zone.
(2) Melting: When the surface temperature of the material reaches the melting point, the material begins to melt and form a molten pool.
(3) Vaporization: When the surface temperature of the material continues to rise and reaches the boiling point, the material begins to vaporize and form steam.
(4) Combustion: For some flammable materials, such as wood and plastic, the high temperature of the laser beam can cause a combustion reaction on the surface of the material, producing gas and further accelerating the cutting process.
Cutting process
The laser cutting process can be divided into the following steps:
(1) Laser beam focusing: The laser beam is focused to a very small point through a focusing lens or a reflecting mirror to form a high power density laser beam.
(2) Material surface heating: The laser beam irradiates the material surface, causing the surface temperature to rise rapidly to the melting point or boiling point.
(3) Cutting head movement: The cutting head moves along a predetermined trajectory, and the laser beam forms a continuous cutting line on the material surface.
(4) Assist gas: Assist gas, such as oxygen, nitrogen or argon, is usually used during the cutting process to help remove molten or vaporized material and improve cutting speed and quality.
(5) Cutting complete: When the cutting head moves to the predetermined position, the entire cutting process is completed.
II. Laser Cutting Operation Method
Equipment Selection
Laser cutting equipment mainly consists of a laser, a cutting head, a CNC system, and a worktable. When selecting laser cutting equipment, it is necessary to choose the appropriate laser power, cutting head type, and CNC system based on the requirements of the material being processed, its thickness, and precision.
Material preparation
Before laser cutting, the material needs to be properly prepared, including cleaning, deburring, and leveling, to ensure a smooth cutting process.
programming
Laser cutting typically employs CNC programming, where computer software generates the cutting trajectory and parameters, which are then transmitted to the CNC system. During programming, factors such as cutting speed, power, and focal point position must be considered to achieve the optimal cutting results.
Setting parameters
Before starting the cutting process, it is necessary to set the relevant parameters for laser cutting based on the characteristics of the material and the processing requirements, including laser power, cutting speed, focal point position, and auxiliary gas.
Operating equipment
When operating laser cutting equipment, it is essential to follow the operating procedures to ensure its safe and stable operation. During operation, carefully observe the cutting results and adjust parameters promptly to achieve satisfactory cutting quality.
Post-processing
After laser cutting is completed, the cut surface needs to be properly post-processed, such as deburring, cleaning, and checking dimensions, to meet the requirements of subsequent processing or use.
III. Key Technical Points of Laser Cutting
Laser power selection
Laser power is a crucial factor affecting cutting results. Excessive power can lead to over-melting and burning of the material, impacting cutting quality; conversely, insufficient power can result in slow or incomplete cutting. Therefore, it is essential to select the appropriate laser power based on the material's characteristics and thickness.
Control of cutting speed
Cutting speed directly affects cutting efficiency and quality. Too high a speed may result in incomplete cutting, while too low a speed will reduce production efficiency. Therefore, it is necessary to rationally control the cutting speed based on the material properties and laser power.
Focus position adjustment
The focal position determines the power density of the laser beam on the material surface, significantly impacting the cutting effect. Generally, the closer the focal position is to the material surface, the better the cutting result. However, a focal position that is too close may cause the laser beam to diverge, affecting cutting accuracy. Therefore, the focal position needs to be adjusted appropriately based on the actual situation.
Selection and control of auxiliary gases
Assist gas plays a crucial role in laser cutting, helping to remove molten or vaporized material and improving cutting speed and quality. Different materials and cutting requirements necessitate the selection of appropriate assist gases, such as oxygen, nitrogen, or argon. Furthermore, the gas pressure and flow rate must be controlled to achieve optimal cutting results.
