High-speed thermal microscopy of plasma microprinting at atmospheric pressure

The HelixJet (https://www.inptdat.de/helixjet) was applied to simultaneous melting and plasma treatment of polyamide (PA 12) microparticles (diameter 60 µm) used conventionally for 3D printing by laser sintering. This proof-of-principle experiment demonstrated that gaussian thickness profiles of PA 12 can be printed using the HelixJet with a rapid rate of 200 mg/s (peak growth 2 mm/s) and with advantageous material properties. The key element of this novel process is the self-regulated balance between material melting and plasma quenching. As a result, particles leaving the HelixJet with the gas flow velocity have a temperature slightly below the melting temperature preventing material degradation that would occur at higher temperatures. The above process has been captured with a high-speed infrared camera. The resulting movie combines the best temporal and spatial resolution for the studied process and reveals the particle temperature of 180°C to 190°C and their velocity of 0.5 m/s to 3 m/s depending on the radial position.