Control of Powder Streams in Coating Technologies

The filling grade of feeder disk grooves is monitored by a laser triangulation sensor. A correlation between groove filling grade and powder feed rate is proven. Applicability of groove filling grade data for realization of effective control loops to secure constant powder feed rates and for determination of optimal hardware setups and parameter settings of disk type feeders are discussed. Stabilizing behavior of powder streams after switching between different powder feed lines using a compact squeeze valve based powder quick switch unit is studied by digital analyses of images taken from illuminated powder streams that exit injectors. The time to re-establish stable powder streams depends on apparent density and feed rates of powders.