Computational and Laboratory Analysis of Thermal Free-Form Fabrication of Metal Prototypes

The advent of rapid prototyping methods for functional layered metal products has created the need for thermal off-line analysis and optimization of the process conditions, as well as for real-time control of the material structure and properties through the temperature field. For this purpose, this work introduces a scanned thermal processing technique, in which the heat source rapidly sweeps the surface of each deposited layer to ensure a flexible heat input distribution. For this method, the article establishes two dynamic thermal modeling tools: a finite-difference numerical simulation of the temperature field in layered objects, and an experimental linearized formulation with time-varying parameters identifiable in-process by thermal measurements. The models are applied and validated in elementary LOM thermal operations on a plasma-arc processing station with infrared thermal sensing and computer control, and their use for design of a closed-loop thermal regulator is discussed, together with the metal structure and properties of scanned parts.