Most 3D printing or laser additive manufacturing (AM) systems use continuous-wave (CW) lasers. However, researchers at PolarOnyx (San Jose, CA) are pioneering AM instruments that use femtosecond pulsed lasers to create 3D objects from high-temperature materials. Furthermore, the well-known athermal ablation properties of ultrafast lasers can simultaneously accomplish subtractive manufacturing in one computer-controlled scanning process for combined additive/subtractive manufacturing that doubles the system's capability and increases productivity without adding cost.
By taking advantage of instantaneous high-temperature plasma generation, femtosecond fiber lasers can sinter such high-temperature metals as tungsten, with a melting temperature of 3422°C and thermal conductivity of 173 W/(m·K), and ceramics including zirconium diboride (ZrB2) with a melting temperature of 3246°C. By tuning the pulse width and energy, microstructure shape and size can be manipulated such that the melted structure is more robust against mechanical and thermal stresses than conventional CW laser AM. Tungsten gears and thin-walled (100 μm) components, for example, have been fabricated with femtosecond laser AM. Reference: S. Bai et al., Appl. Phys. A, 122, 5, 495 (May 2016).
