Abstract: A thermal spraying method for coating an inner surface of a cylinder of an internal combustion engine or a piston engine. The method includes applying a thermal spray layer to the inner surface of the cylinder via a spray jet which is emitted by a spray torch and which includes a spray material, optically monitoring, via an optical sensor device, surroundings of the spray jet as defined by a space outside the spray jet, and assuming a coating process to be defective if the optical sensor device detects one or more particles of the spray material supplied to the spray torch in the surroundings monitored outside the spray jet and a parameter of the one or more particles exceeds a defined threshold.

Abstract: A thermal spraying method for coating an inner surface of a cylinder of an internal combustion engine or of a piston engine. The method includes applying a thermal spray layer onto the inner surface of the cylinder so as to obtain a coated inner surface, inserting an optical sensor device into the cylinder, and scanning the coated inner surface via the optical sensor device in order to detect at least one of a ridge and an indentation in the thermal spray layer. A thermal spray torch for the method includes an optical sensor device which is inserted into the cylinder and to scan the coated inner surface of the cylinder so as to detect at least one of a ridge and an indentation in the coated inner surface.