Spatter reduction by multi-beam illumination in laser powder-bed fusion

Abstract

Modulation of laser radiation is a promising approach to increase the process speed in laser powder-bed fusion. However, with an increased buildup rate, the preservation of product quality must be guaranteed. For this purpose, we investigated spatter generation with single-beam and multi-beam distributions for single tracks and printed objects. The investigation with a coaxial high-speed camera to capture thermal radiation of spatters and an off-axis high-speed camera for a qualitative observation of the melt pool led to a better understanding of spatter generation. The results showed dependency of power and scan velocity on the number of spatters. Furthermore, we showed that the application of multi-beams preserves the number of spatters per track at higher applied power. Due to the wide melt pools and fewer required hatches, the total number of spatters in a generated part was significantly reduced. In addition, by means of high-speed recordings, it was shown that melt pools with high volume have a higher stability against impurities of the powder bed and spatters. Finally, the application of multi-beam illumination led to a higher buildup rate with reduced spatter particles.

Keywords

• Laser powder-bed fusion
• Multi-beams
• Process monitoring
• Spatters