Spraying is a coating method in which spray guns or disc atomizers are used to disperse into uniform and fine droplets by means of pressure or centrifugal force and apply to the surface of the object to be coated. It can be divided into air spraying, airless spraying, electrostatic spraying and various derived methods of the above basic spraying forms, such as large flow and low pressure atomization spraying, thermal spraying, automatic spraying, multi-group spraying, etc.