Ballating Phenomenon in Laser Sintering
Ball formation during laser sintering is the uncontrolled balling of the molten strand due to excessive energy density or insufficient wetting, leading to surface roughness and impairing layer quality.
Physical-Chemical Mechanism of Action
During laser sintering, the melt pool forms a ball segment when the laser energy is too high or wetting is poor. This causes the strand to cool unevenly and contract into a dome shape.
Metallurgical Relevance & Welding Risks
Ball segment formation affects the surface quality of the weld bead by making it irregular and causing cracks or pores. This can lead to poor layer density and reduce the hardness of the welded steel body.
Workshop Practice & Action Instructions
To avoid ball segment formation, the laser energy density should be controlled. Excessive energy can be reduced by adjusting the laser power or using a protective shield. Additionally, adequate wetting with a suitable flux is essential. The wetting spray rate should be set so that the bead is evenly covered and no air bubbles form.