In-layer Thermal Control of a Multi-layer Selective Laser Melting Process

TL;DR

This paper develops a control-oriented thermal model for multi-layer SLM, introducing an in-layer controller to manage temperature and reduce defects, demonstrated through simulation results.

Contribution

It presents a novel structured model reduction method and an in-layer thermal control strategy for multi-layer SLM processes.

Findings

Controller effectively prevents layer-to-layer heat buildup

Low-order models achieve good closed-loop performance

Thermal control reduces residual stress and defects

Abstract

Selective Laser Melting (SLM) is an additive manufacturing technology that builds three dimensional parts by melting layers of metal powder together with a laser that traces out a desired geometry. SLM is popular in industry, however the inherent melting and re-solidification of the metal during the process can, if left uncontrolled, cause excessive residual stress, porosity, and other defects in the final printed parts. This paper presents a control-oriented thermal model of a multi-layer SLM process and proposes a structured model reduction methodology with an associated reduced order model based in-layer controller to track temperature references. Simulation studies demonstrate that the controller is able to prevent layer-to-layer heat buildup and that good closed-loop performance is possible using relatively low-order models.