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Coming from ENS Cachan with a typical background in mechanical engineering, particularly from a manufacturing point of view, I am doing a thesis in the COSMER laboratory in the field of additive manufacturing.
Holder of an aggregation in industrial sciences of engineering with a mechanical option
Subject of the thesis : Additive manufacturing by multi-axis robotic wire deposition
Optimization of the deposit trajectories and robot control
Thesis Director : Vincent HUGEL, PR, University of Toulon, COSMER Lab
Co-supervisor of the thesis : Sébastien CAMPOCASSO, Assoc. Prof., University of Toulon, COSMER lab
For several years, additive manufacturing has been booming in the industrial sector for the direct production of small series of functional metal parts. However, powder bed technologies currently have high manufacturing costs and dimensional limits (about 600 mm) that hinder their diffusion in certain industrial sectors such as aeronautics or naval. Multi-axis direct deposit techniques are currently in strong development because they offer larger working dimensions, possibilities of recovery on parts (repair, addition of entities…) and can be combined with machining processes to lead to so-called hybrid manufacturing processes.
Additive manufacturing by wire deposition is a process that many manufacturers are relying on to reduce part manufacturing costs in the future. Indeed, this very flexible technology has many advantages compared to other additive manufacturing processes: low investment (around 100 to 500 k€, compared to 600 k€ to 1.5 M€ for powder bed processes and 800 k€ to 2 M€ for powder spraying), large working space (several meters), high productivity (several kg/h compared to a few g/h), good metallurgical quality (defects similar to welding, no porosity.), low downtime and material loss, low cost and fast material changeover, reduced HSE risks compared to metal powders…
Wire deposition using industrial robots is therefore a process that could improve the competitiveness of the aeronautics industry and appears ideal for manufacturing applications of the naval industry given the small series and large dimensions of the parts produced. These two target sectors are major economic players in the PACA region.
Currently, the additive manufacturing machines on the market offer few possibilities for adjustment and modification due to the locks imposed by the manufacturers. The possibilities of research work on these means are thus limited. The use of industrial robots coupled with direct deposit systems makes it possible to obtain large and more “open” manufacturing facilities. Specific developments can thus be carried out in order to optimize a targeted manufacturing process. This optimization requires simultaneous control of the parameters of the deposition process (energy, yarn feed rate, etc.), but also of the trajectory and feed rate of the “depositing point”. It is also possible in some cases to vary the deposition orientation, and thus to remove the manufacturing media. Nevertheless, successful manufacturing requires the ability to generate complex three-dimensional deposition trajectories that allow the part to be “filled” correctly according to its geometry and that of the deposited bead. However, the bead and part geometries can vary depending on process parameters, part temperature or deposition orientation with respect to gravity.
Trajectory generation is a common problem for all direct deposition processes (Direct Energy Deposition) on multi-axis machines, whether they use powder spraying or wire deposition regardless of the fusion technology (arc with coated electrode, MIG-MAG, TIG, plasma, laser, or even electron beam). The consideration of thermal problems when generating trajectories is also a research area that is the subject of some work recently initiated for powder bed processes. The proposed thesis topic therefore aims to complement the current work on trajectory optimization in the case of the wire deposition process.
64-hour monitoring mission per year within the IUT GMP in Toulon
- Machine metrology
- Practical work in production