Study on Paint Coating by Electrostatic Rotary Atomizer (II)

Effect of Particle Diameter and Specific Charge on Transfer EffFciency

Abstract

The effects of spraying conditions on specific charge (charge to mass ratio), diameter of paint particles and transfer efficiency were studied with a high-speed electrostatic rotary atomizer. On the basis of these results, the effect of specific charge and particle diameter on transfer efficiency was discussed. The results are summarized as follows :
1. Specific charge is almost independent of cup rotational speed and air flow rate for spray pattern adjustment. However, specific charge increases with the increase of applied voltage, and with the decrease of paint flow rate and paint viscosity. The contribution of the factors to the increase of the charge is in the following order ; applied voltage>>paint flow rate>paint viscosity.
2. The diameter of paint particles is little influenced by applied voltage and air flow rate. However, the diameter decreases with the increase of rotational speed, and with the decrease of paint flow rate and paint viscosity. The contribution of the factors to the decrease of the diameter is in the following order ; paint flow rate>rotational speed>paint viscosity.
3. When specific charge is less than that of the practical use, transfer efficiency increases to 90% with specific charge. In the low specific charge region within the practical use, transfer efficiency is more than 90%, and depends on specific charge and diameter of paint particles. In the high specific charge region, transfer efficiency gradually increases only with the diameter.