Date Time A Route for Avoiding Defects During Additive Manufacturing Laser powder bed fusion is a dominant additive manufacturing technology that has yet to reach its potential. The problem facing industry is that tiny bubbles or pores sometimes form during the printing process, and these pores create weak spots in finished products. When a slow-speed, high-power laser is melting metal powder during the 3D printing of a part, a keyhole-shaped cavity in the melt pool can result. Pores, i.e., defects, form at the bottom of the keyhole. New research published in Science reveals how the pores are generated and become defects trapped in solidifying metal.