Additive manufacturing, commonly known as 3D printing, integrates computer-aided design, material processing, and forming technologies. Based on digital model files, it is a manufacturing technology that uses software and numerical control systems to build solid objects by layering specialized materials layer by layer through methods such as extrusion, sintering, melting, photopolymerization, and jetting. Unlike traditional subtractive manufacturing methods that involve material removal (cutting) and assembly, it is a 'bottom-up' manufacturing approach that builds up material, making it possible to fabricate complex structural parts that were previously constrained by conventional manufacturing methods.

Currently, there are three main mature metal additive manufacturing technologies:
1. Selective Laser Melting (SLM) processes the 3D model of the workpiece by slicing it into layers. A laser beam is used to selectively melt the metal powder. After each layer is scanned, a new layer of powder is spread over the previously formed area, and the process is repeated until all slices are scanned, achieving layer-by-layer accumulation of the workpiece.
2. Laser Metal Deposition (LMD), also known as laser direct manufacturing, uses a higher-power laser. The material feeding method is typically synchronous powder feeding, and its key technical feature is direct deposition in a layer-by-layer manner. Compared to traditional processes, it offers high flexibility and a short process cycle, significantly reducing costs and time, and holds great potential for producing small batches of high-value metal components.
3. Electron Beam Melting (EBM) uses an electron beam under high vacuum conditions to melt and form metal powder. The vacuum environment and the use of an electron beam are the main distinctions of EBM from other processes. Parts manufactured using EBM technology exhibit good density and very high strength.

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