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On-line Optical Diagnostics of a Rotating Internal Diameter Plasma Spray Gun Used for Coating of Cylinder Bores in Automotive Industry


 Coating of cylinder bores using plasma spraying is a growing application of thermal spraying in automotive industry. The Sulzer Metco RotaPlasma manipulator provides continuous rotation of the internal diameter plasma gun and enables a cost-efficient and reliable coating of the cylinder blocks. The development towards more advanced quality control systems and closed-loop spray control systems requires an on-line measurement of the most important particle and spray parameters such as particle temperature, velocity and flux. However, the small dimensions of the plasma plume of an internal diameter spray gun together with the rotation of the gun makes the measurement difficult, if not impossible, for many traditional diagnostics equipment. In this work, SprayWatch, an imaging CCD camera based diagnostics system from Oseir Ltd. was used for measuring particle and spray parameters during the rotation of an internal diameter plasma spray gun. The results show that the SprayWatch camera system is a promising tool for both development and production monitoring of cylinder bore coating process, as well as for realising a closed-loop spray control system.