An empirical model for feedforward control of laser powder bed fusion

TL;DR

This paper develops an empirical, control-oriented model of melt pool behavior in laser powder bed fusion and demonstrates a feedforward control strategy to regulate laser power, improving melt pool stability across geometries.

Contribution

It introduces a novel empirical model of melt pool geometry dependence and applies it to design a model-based feedforward controller for laser power regulation.

Findings

The melt pool footprint exponentially increases with shorter scan lines.

The empirical model accurately predicts melt pool behavior across geometries.

The feedforward controller effectively suppresses melt pool deviations in experiments.

Abstract

While considerable progress has recently been made in real-time melt pool monitoring for laser powder bed fusion (LPBF), results in in-situ melt pool control are relatively sparse, a major reason being lack of suitable control-oriented models. This study demonstrates an empirical control-oriented model of geometry-dependent melt pool behavior, and subsequent melt pool regulation with a model-based feedforward controller for laser power. First, it shows that the melt pool "footprint" exponentially increases when the scan lines become shorter. The empirical model of this behavior is developed and validated on different geometries at different laser power levels. Second, the developed model is used to design a feedforward controller for obtaining optimal laser power profiles. This controller is then validated experimentally and is demonstrated to suppress the in-layer geometry-related melt pool signal deviations, for different part geometries.