Melt Pool Size Control in Thin-Walled and Bulky Parts via Process Maps

Control of melt pool size is critical for maintaining consistent build conditions in the solid freeform fabrication of complex shapes. In this research, melt pool size in laser-based solid freeform fabrication processes is studied for both thin-walled structures and bulky parts. Numerical simulations are used to construct non-dimensional plots (termed process maps) that quantify the effects of changes in part height, laser power, deposition speed and part preheating on melt pool size. Strategies for the control of melt pool size suggested by the process maps are similar for the two geometries. Insights are given as to how transitions between these two extremes in geometry can be managed to maintain a consistent melt pool size. This modeling work is being performed in tandem with process development and melt pool imaging and control research underway on the LENS process at Sandia National Laboratories