The volumetric energy density (VED) equation in laser powder bed fusion serves as an elementary model of the laser energy delivered to the powder bed. This metric, composed of critical process parameters, is often correlated with part health metrics such as porosity content to assess the efficacy of selected laser settings. This widely used formulation is often hindered by its simplicity, with its limitations most apparent when comparing trends across different alloys or across diverse parameter-set designs where multiple parameters are adjusted. This study aims to modify the VED formulation to account for these deficiencies.
In this research, a modified VED equation is proposed that preserves the units and simplicity of the original formulation while effectively addressing known flaws. This more robust equation is developed by incorporating additional laser parameters and material properties. Specimens from multiple materials, machines and parameter set designs were characterized to validate the formula.
All variables converge onto a single curve, correlating porosity and the new VED value, providing compelling evidence for the modifications’ effectiveness.
To the best of the authors’ knowledge, while other modifications to the VED formula exist, this is the first iteration that incorporates all major process parameters: laser power, scan speed, hatch spacing, layer thickness and spot size. This updated formula can also uniquely resolve differences between samples fabricated with different parameter sets that have the same VED.
