Selective Laser Melting, SLM) is an advanced additive manufacturing (3D printing) technology, which is widely used in aerospace, medical equipment, automobile manufacturing and other fields. In the process of SLM, laser power is one of the key process parameters that affect the forming quality. How to accurately control laser power is not only related to the compactness, surface quality and mechanical properties of parts, but also directly affects the stability and efficiency of manufacturing process.

First, the role of laser power in SLM

In SLM system, the high-energy laser beam scans the metal powder layer according to the preset path, so that it melts locally and solidifies rapidly to form a solid structure. The laser power determines the energy input. If it is too high, it may lead to overheating and spheroidization of materials, while if it is too low, it will lead to problems such as incomplete fusion and increased porosity. Therefore, accurate control of laser power is the core to achieve high-quality metal parts manufacturing.

Second, the control mode of laser power in SLM

1. Constant power mode
In the early SLM equipment, the constant power output mode was often adopted, that is, the laser power was kept constant during the whole scanning process. This method is suitable for machining parts with simple structure and regular shape, but it is easy to cause uneven energy distribution when dealing with complex structures or areas with different thicknesses, which will affect the final forming quality.

2. Dynamic power regulation
With the development of control technology, modern SLM equipment generally adopts dynamic power adjustment technology. By adjusting the laser power in real time to adapt to the heat accumulation and material characteristics in different regions, thermal stress can be effectively reduced and defects can be avoided. For example, reduce the power in the edge or thin-walled area to prevent overheating, and appropriately increase the power in the filled area to ensure full fusion.

3. Intelligent control based on process parameter database
Combined with the process parameter database and artificial intelligence algorithm, the optimal power parameters can be automatically recommended according to the material type, geometric characteristics of parts, layer thickness and other factors. Some advanced equipments even have the function of online monitoring and feedback adjustment, which can detect the molten pool state in real time by infrared camera or spectrometer and dynamically optimize the laser power setting.

Iii. Factors affecting laser power control

-Material characteristics: Different metal materials have different absorption rate and thermal conductivity to laser, so they need to match different power parameters.
-Scanning speed and scanning distance: the laser power should match the scanning speed. The faster the speed, the higher the power is usually needed to maintain sufficient energy density.
-Ambient temperature and protective atmosphere: inert gas atmosphere and substrate temperature will also affect the melting effect, and then put forward different requirements for laser power.

Fourth, the future development trend

With the development of SLM technology towards high precision, high speed and intelligence, the laser power control system will be more refined and automated. In the future, SLM equipment will integrate more sensors and AI algorithms to realize the leap from "parameter setting" to "process control", and further improve the forming quality and production efficiency of parts.

In a word, the control of laser power is the core link in SLM technology. By continuously optimizing the control strategy and introducing intelligent control means, it will help to promote the metal additive manufacturing technology to a higher level of application.