Coating thickness of article measured immediately after application - by radiometric thickness method and used to regulate coating apparatus

摘要

A method of determining and/or controlling the thickness of a coating, such as a lacquer or powder coating, applied to workpieces, for example by spraying or sprinkling, where the thickness is adjusted either by adjusting the coating apparatus or adjusting the speed of travel of the workpiece through the apparatus, is as follows. The thickness of the coating or on a test piece coated simultaneously with it, is measured by a known radiometric thickness measuring method without contact, pref. immediately after the workpiece leaves the coating apparatus. Pref. the workpiece or test piece passes the radiometric coating thickness apparatus in a zone outside a spray cabin surrounding the coating apparatus; the distance between the workpiece and the test apparatus is kept constant, at least during the measuring operation. The method makes possible immediate checking of the coating thickness and therefore almost immediate adjustment of the coating apparatus if a fault or deviation occurs. This is by contrast to the known methods, where the coating thickness is measured by a contacting process after the coating has hardened, and there is therefore a delay of 20-30 minutes before the coating device can be re-adjusted. A typical example of use is in a coating plant for the electrostatic powder coating of refrigerator components.