Environmental and economic comparison between WAAM and machining

Title (original): A modelling framework for comparing the environmental and economic performance of WAAM-based integrated manufacturing and machining.

Authors: P. C. Priarone, G. Campatelli, F. Montevecchi, G. Venturini, L. Settineri.

Keywords: Sustainable development; Additive Manufacturing; Machining.

Purpose: Additive Manufacturing has proved to be suitable for supporting or even replacing traditional manufacturing approaches in some industrial contexts. Among the various processes that can be used to produce metal parts, Wire Arc Additive Manufacturing (WAAM) is known to be an economically convenient, welding-based direct energy deposition technique for large parts with reduced complexity. The present paper proposes a structured modelling framework to assess whether WAAM could successfully substitute machining processes. The costs, manufacturing times, energy demand and carbon footprint are considered.

Methodology: WAAM is a welding-based technique that is suitable for producing three-dimensional geometries, layer-by-layer. A substrate to build the part on is needed. For this purpose, one industrial best practice is the use of simple-shaped portions of the final component, previously manufactured by means of other processes (such as machining). This strategy can prevent the detachment of the additively manufactured part from the base plate, and allows conventional technologies to be used to produce the massive features. However, this also implies the need of several manufacturing steps with different material feedstocks. In addition, a post-AM finishing process is required, since the quality of the as-deposited surfaces is low. A framework that can be used to assess and compare the performance of a WAAM-based approach and machining has been proposed.

Findings: The methodology has proved to be suitable for identifying whether WAAM could successfully substitute machining processes. Even if the conclusions are limited to the considered part under investigation (which did not need support structures to be built), the integrated approach appears to be favourable towards environmental stress, when it is possible to exploit its superior efficiency for raw material usage, even at the expense of higher processing times and costs.

Practical implications: Industries adopt WAAM for the high productivity and the speed of realization of the manufacture article with unparalleled efficiency and cost advantages in the production of large parts.

Full reference: PRIARONE, Paolo C., et al. A modelling framework for comparing the environmental and economic performance of WAAM-based integrated manufacturing and machining. CIRP Annals, 2019.

Link: https://www.sciencedirect.com/science/article/pii/S0007850619300319

Grafical abstract: Unit processes and main qualitative flows of the WAAM-based integrated manufacturing approach.