CONTINUOUS DIRECTED LASER PREHEATING OF BIG AREA ADDITIVE MANUFACTURING

With the development of big-area additive manufacturing (BAAM) or large format additive manufacturing (LFAM), optimizations of the printing process are made to obtain controllable and stable mechanical performance. In this work, we propose a continuous laser preheating technology for LFAM to achieve higher interlayer bonding strength. Multiple laser diodes are used and built in a ring form to realize the continuous heating process. With multiple laser diodes around the nozzle, the preheating area can be retargeted continuously without rotating the extrusion head or laser source. Compared to the laser-heating source fixed in one direction, switching laser diodes can offer much more printing possibilities and flexibilities. A significant mechanical improvement by using a directed laser heating is achieved. The mechanical testing results showed that with 15W laser power, the flexural strength in the out-of-plane direction reaches up to 80% - 90% of that in the in-plane direction. The highest flexural strength is 86.5Mpa, which is 137% more than that of the specimens without laser heating.