Towards wire and arc additive manufacturing of high-quality parts

Recently an increasing application of materials that are difficult to machine can be observed in the aerospace industry. Due to their annual growth rate of 15 % titanium alloys are a prominent example. A particular challenge is the manufacturing of large-volume structural components made of titanium alloys. Current production processes based on current technologies lead to a high degree of removed material that often exceeds 85 %. Consequently, the material waste is immense resulting in high production costs. Additionally, high tool costs arise from the extensive tool wear during machining. Wire and Arc Additive Manufacturing (WAAM) is a promising technology to reduce the material waste and the production costs. Based on a Gas Metal Arc Welding (GMAW) process, near-net-shape components are produced by deposition welding. Thereby, the wire electrode material is placed dropwise on a substrate creating an additively manufactured part. This paper presents experimental investigations on the formation of the part geometry during WAAM. Based on the experimental results, the characteristics of the geometry are linked to the process parameters. Finally, a concept to monitor the manufacturing process and detect the formation of defects is presented. Process instabilities, i.e. geometrical as well as thermal irregularities can indicate defects such as cracks or pores in the component. A better understanding of the process and the ability to reliably detect occurring defects during the process can support the certification of WAAM-manufactured components for aerospace applications.