An experimental study on process modeling for selective laser melting*

This paper addresses process modeling for the selective laser melting (SLM) process. We experimentally investigate the response of the SLM process output (measured by a coaxial near-infrared camera) to changing input laser power. We determined that first and second order models can be used to capture this input-output behavior. Next, we studied the dependency of this transfer function on laser scan speed and other process variables that evolve over a typical part build, such as thermal properties of surrounding medium (bulk powder, build plate, or solidified part) or layer number. The transfer function was found to strongly depend on the material environment (solidified material or bulk powder). Further, transfer function also depended on the layer number, exhibiting transient behavior. We report identified 1st order transfer functions for different scan speeds, locations on the build plate, and different layer numbers. Identified models and quantification of their variability will serve as foundational work for the future implementation of advanced real-time process control algorithms.