Optimized robot trajectory generation for thermal spraying operations and high quality coatings on free-form surfaces

For high process reproducibility and optimized coating quality in thermal spray applications on complex geometries, APS (Atmospheric Plasma Spraying) and HVOF (High Velocity Oxygen Fuel) torches are guided by advanced robot systems. The process parameters defined by the robot movement in thermal spraying operations, such as the trajectory, the relative distance, velocity profile and angle between the spraying torch and the substrate, have a major influence on the heat and mass transfer to the component during the process, and therefore on the coating microstructure, physical and chemical properties and their quality. This fact, coupled with the increasing demand of reproducible, high dimensional accurate coatings on free-form surfaces, leads to the necessity of developing software tools for optimized robot trajectory generation.The purpose of this study was to implement an advanced computer aided robot path planning approach for thermal spraying operations which allows the generation, simulation and implementation of the robot trajectory. The optimized generated trajectory and speed profile are integrated in coupled CFD (Computational Fluid Dynamics) and FEM (Finite Element Method) models to analyze their influence on the heat and mass transfer during coating deposition. The developed software tools were applied to coat real components with complex geometry by using the High Velocity Oxygen Fuel (HVOF) spraying system and with WC–Co as the reference spraying material.