The main goal of this doctoral study is to investigate and develop knowledge for the use of additive manufacturing (AM) in repair of large metal components.
When purchasing a component, price is one of the main selection criteria. However, when a repair is needed, this changes drastically as lead time plays a much larger role. This is especially true for critical components, e.g. valves and other large components in the maritime, oil and gas industry. In such industries, the loss of income due to downtime tends to be so substantial that repair cost is of little significance. Limited access to highly skilled welders has posed a problem for this industry for years, a problem that became even worse during the Covid pandemic with travel restrictions and closed borders. This backdrop makes it very interesting to develop prequalified technologies that make repair work, either in the field or in workshops, less sensitive to operator skill.
SINTEF Manufacturing have a long history of research on powder bed methods. Such methods can produce high resolution, intricate geometries and nice surfaces. The only problems are that build chamber size will put strong restrictions on component size and the process is relatively slow. Using such methods for repair is also problematic, since the powder bed methods are limited to starting its build form a flat, even surface without any points protruding beyond the starting level. To broaden both competence and capabilities, SINTEF Manufacturing have invested in a "directed energy deposition", DED, build head from Meltio, which by integration on a robotic arm is capable of producing large parts. The process is slower, but more precise than arc-based methods, and therefore, it is something in-between powder bed and arc-based methods. This equipment enables a good balance between process control, high productivity and generous geometrical freedom.
Expected future work will be to look into hybrid technologies for combining grinding, machining, machine vision and 3D scanning, since all these operations are likely to be necessary activities during component repair.
These are the main activites of 2022:
x Assembling the DED hybrid cell at SINTEF Manufacturing in Valgrinda.
x Writing, presenting and publishing an article on design aspects in constructing a cell design for hybrid additive and subtractive production. The work was presented at IWAMA-conference and accepted for publication in Lecture Notes of Electrical Engineering (LNEE) by Springer.
x Elementary studies on producing simple geometries in 316L, 2209 duplex, aluminum-bronze, Inconel 625 and Inconel 718.
x A study on robot programming of a DED-AM.
x Establishing a method for parameter development for buildability and microstructural integrety.
x Established cooperation with a PhD-candidate from SFI Manufacturing at NTNU and a master student at material science regarding multi-material production of aluminium bronze on Inconel 718. Most of the process parameter development is done, and smaller samples with good quality has been produced. In the beginning of 2023, the aim is to produce larger samples of these multi material parts.
x 4 out of 5 compulsory subjects have been completed:
- IFEL8000 – Introduction to Research Methodology, Theory of Science and Ethics: Approved
- PK8102 - Material Removal Processes: Approved
- MM8410 - Additive Manufacturing of advanced Alloys: Waiting for exam result
- MT8219 - Applied Electron Microscopy: Waiting for exam result