Planning robotic trajectories for thermal spray shape deposition

Thermal spray shape deposition is a new process for fabricating net-shape parts by incremental material buildup of cross-sectional layers. This article presents an approach for spraying thin, flat layers using a robotic thermal spray system. Asymmetries of the spray distribution are first corrected by tilting the spray torch based on a computer model of the measured spray distribution. The path of the torch is then found using heuristics that are based on the estimated standard deviation of the corrected distribution. For example, thick arc-sprayed coatings of approximately 4.0 mm thickness have been deposited using this method, with the resulting standard deviation from the mean thickness ranging from 20.0 to 30.0 μm. To demonstrate the shape deposition process, a prototype turbine blade shape was built using these optimized trajectories.