Post-processing of metallic parts produced by additive manufacturing

Author(s)

Adriel Magalhães Souza

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2023-03-01

Examining board members

Eraldo Jannone da Silva; Reginaldo Teixeira Coelho; Eder Socrates Najar Lopes; Milton Pereira; Rosemar Batista da Silva

• Advisor: Eraldo Jannone da Silva

Abstract

Additive Manufacturing (AM), commonly referred to as 3D printing, has been considered a highpotential disruptive technology, with a significant increase in recent years. The products made through this process are created by adding layers of material until the forming of the component becomes close to the final geometry (near net shape). Regarding metal AM techniques, one of the main methods is Directed Energy Deposition (DED), which combines the material and energy supply for layer by layer simultaneous composition and, consequently, the forming of the piece. However, the components made through this method present low dimensional tolerance and poor surface finish, creating a need for post-processing. Based upon this context, this work mainly aims to investigate the feasibility of adopting abrasive processes (grinding and magnetic abrasive finishing - MAF) for post-processing of metallic parts produced with DED. Surface characteristics (shape deviation, roughness, microstructure, and residual stress) and process output variables (material removal rate, processing time, cutting forces, and specific energy) were the evaluated parameters. The results showed that the combined post-process chain improves form accuracy and surface quality of the DED-produced parts with no observable changes in their near-surface microstructure and hardness. The residual stress was altered by the application of post-processes, in which milling induced tensile residual stress, grinding introduced compressive residual stress, and MAF did not significantly modify the stress state. As main conclusions, milling and grinding operations between DED and MAF minimizes polishing time. Adding grinding lead to decrease in the material removal in MAF, but reduces the time needed for polishing and the overall specific energy (AU)

• FAPESP's process: 19/10758-4 - Study and development of post-processing in metal parts produced by additive manufacturing: application of high speed machining/grinding and magnetic abrasive finishing process
• Grantee: Adriel Magalhães Souza
• Support Opportunities: Scholarships in Brazil - Doctorate