For liquid coatings, increasing the strength of the atomized air or the rotating speed of the cup usually helps to reduce the median diameter of the droplets and narrow the particle size distribution under some working conditions, but not the higher the better. Excessive atomization may result in over-spraying, dry-spraying, excessive solvent volatilization, blurring of edges, rebounding, or reduced transfer efficiency. For powder spraying, the air pressure and rotating speed of the rotating cup mainly change the powder delivery, dispersion, aggregate fragmentation, powder cloud speed and spatial distribution, which cannot be simply understood as changing the D50 of the original powder particles. Whether it can meet the requirements of high gloss or ultra-thin coating can not only look at the median diameter; but also verify D10/D50/D90, distribution width, flow stability, transfer efficiency, film thickness uniformity, leveling, orange peel, pinhole, edge covering, curing and long-term repeatability.
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