Researchers at Lawrence Livermore National Laboratory (LLNL) recently made an important discovery related to what's commonly known as spatter. Spatter happens frequently during powder bed fusion additive manufacturing processes, and it involves tiny particles of liquid metal being ejected from the laser's path. This can result in contamination of the powder bed and issues such as porosity, roughness and lack of adhesion in the finished parts. It has been believed that spatter is caused by the laser's recoil pressure, but the LLNL researchers have discovered that it's actually due to the entrainment of metal particles by an ambient gas flow. They came to this conclusion after combining high-speed imaging of melt pool dynamics with high-resolution computer simulations. Read more at