Melting Metal with Light
Selective laser melting directs a focused laser beam across a thin bed of metal powder, creating a tiny melt pool that solidifies in microseconds as the beam moves on. Layer after layer — each just 20-60 μm thick — fuses into a fully dense metal part with mechanical properties rivaling forged components. The process operates in an inert argon atmosphere at temperatures exceeding 3000°C at the melt pool center, with cooling rates of 10⁶ °C/s that create unique microstructures impossible to achieve by conventional manufacturing.
The Energy Density Window
Volumetric energy density E_v = P/(v×d×t) is the master parameter of SLM. Below ~40 J/mm³, the powder does not fully melt, leaving lack-of-fusion pores that act as crack initiators under fatigue loading. Above ~100 J/mm³, excessive energy creates keyhole-mode melting with trapped gas porosity. The optimal window — material dependent but typically 50-100 J/mm³ for titanium — produces parts exceeding 99.5% theoretical density.
Melt Pool Physics
The melt pool is a dynamic system driven by Marangoni convection (surface-tension-driven flow), recoil pressure from metal vaporization, and rapid directional solidification. Its width, depth, and stability determine whether the build succeeds or fails. The simulator models melt pool dimensions as a function of process parameters, visualizing how the pool elongates at high scan speeds and deepens at high powers.
Defects and Quality
SLM quality is governed by the competition between three defect regimes: lack of fusion (insufficient energy), keyholing (excessive energy), and balling (surface-tension instabilities). Process maps that plot laser power versus scan speed show a narrow corridor of high-density, defect-free processing. This simulator helps you navigate that corridor, visualizing how each parameter change shifts the melt pool toward or away from defect boundaries.