Metal 3D printing technology is reshaping the high-end manufacturing paradigm, with core processes including SLM, LENS, and EBSM, demonstrating disruptive potential in fields such as aerospace and biomedicine.

1. Laser Selective Melting (SLM): Balancing High Precision and Densification

SLM technology uses a 200-1000W fiber laser to melt metal powder layer by layer, with typical process parameters of layer thickness of 20-50 μ m, scanning speed of 600-1500mm/s, and spot diameter of 50-100 μ m. The EOS M400-4 four laser system uses dynamic beam shaping technology to control the grain size within 15 μ m, resulting in a yield strength of 1200 MPa for Inconel 718 alloy. SLM Solutions' circulating wind field design can control the oxygen content below 50ppm to avoid embrittlement during titanium alloy printing.

2. Laser engineering net forming (LENS): additive manufacturing of large-sized components

LENS technology adopts coaxial powder feeding method and can handle components with a maximum diameter of 1.5m. The Optomec LENS 850-R system achieves precise forming of complex surfaces through five axis linkage control. In the repair of aircraft engine blades, LENS technology can control the thickness of Ni based alloy coating within 0.3-1.5mm, combined with in-situ heat treatment process, to achieve a hardness matching degree of 98% between the repair area and the substrate.

3. Electron Beam Selective Melting (EBSM): Advantages of High Energy Efficiency and Vacuum Environment

EBSM technology uses a 60kV electron beam to melt powder in a vacuum environment, with an energy utilization rate of 75%, which is 5 times higher than SLM technology. The Arcam Q20plus system uses dynamic focusing technology to reduce the beam spot diameter to 0.1mm, achieving ultra-fine printing with a layer thickness of 0.05mm. In the manufacturing of cobalt chromium alloy dental stents, EBSM technology reduces the surface roughness Ra to 3 μ m, meeting the ISO 13485 medical certification standard.

4. Multi material printing and post-processing innovation

The hybrid SLM-CNC equipment developed by the Fraunhofer IAPT research institute in Germany can integrate milling processing during the printing process, improving dimensional accuracy to ± 0.02mm. In terms of post-processing, the HP Metal Jet S100 introduces a chemical polishing process to remove surface step patterns through a hydrofluoric acid nitric acid mixed solution, reducing the Ra value from 10 μ m to 0.8 μ m. More cutting-edge research has shown that combining SLM with cold spraying technology can prepare gradient functional materials that meet the extreme requirements of spacecraft thermal protection systems.