On the influence of Gaussian and Ring-shaped beam profiles on quality and energy efficiency in LPBF

Additive Manufacturing (AM) has the potential for improving sustainability of metal processing through decreased energy and materials usage compared to casting and forging. LPBF is finding increasing interest in many industrial fields because of its benefits such as: short time to market, reduced material waste, possibility to obtain complex geometries. Among these intriguing potentialities, the impact of overall energy consumption has not been well characterized. One of the major drawbacks to LPBF is its slow build speed on the order of 5-10 cubic centimeters per hour print speed. Traditionally LPBF systems use Gaussian beams as a heat source, which has a laser beam profile including a high concentration of energy at the center of the beam with a drop off in energy towards the edges. Alternatively, a ring laser will have a more even energy distribution throughout the laser profile. The use of a ring laser beam in LPBF of metal alloys still is at its infancy because it is a novel technology and very few studies exist on its implications from both mechanical and sustainable perspectives. This experimental study investigates how to increase the productivity of LPBF process by switching from a traditional Gaussian laser shape to a ring laser shape using an nLight multi-modal laser. The objective is to increase productivity and reduce energy consumption, without sacrificing mechanical properties by switching to the ring laser, thus improving the sustainability for LPBF. Results include measuring the energy consumption of an Open Additive LPBF system during printing with a stock Gaussian laser vs the nLight laser, and comparing the microstructure and mechanical properties of the two different laser shapes.