Things to note in the process of electrostatic coating
1. Spraying voltage
1.1 In a certain range, when the spraying voltage increases, the powder adhesion increases, but when the voltage exceeds 90KV, the powder adhesion decreases with the increase of voltage.
1.2 When the voltage increases, the initial growth rate of the powder layer increases, but with the increase of the spraying time, the effect of voltage on the increase rate of the powder layer thickness becomes smaller.
1.3 When the spraying distance (refers to the distance from the gun head to the surface of the workpiece) increases, the influence of voltage on the thickness of the powder layer becomes smaller. The general distance should be mastered between 150-300mm.
1.4 Spraying voltage is too high, will make the powder layer breakdown, affecting the quality of the coating. Spraying voltage should be controlled between 60-90KV
2. Powder supply air pressure
Powder supply air pressure refers to the air pressure of the powder delivery tube in the powder supply device, in other conditions remain unchanged, to 0.05MPa (1.96kg force pressure) as the best.
3. Powder spraying quantity
The amount of powder sprayed is the amount of powder coming out of the nozzle mouth per unit of time. The initial growth rate of the powder layer thickness is proportional to the amount of powder sprayed, but with the increase in spraying time, the impact of the amount of powder sprayed on the growth rate of the powder layer thickness not only becomes smaller, but also make the deposition efficiency decreases, so the amount of powder sprayed mastered in 100-200g/min is more appropriate.
4. Spraying distance
Spraying distance refers to the distance from the spray gun to the surface of the workpiece, when the gun applied electrostatic voltage remains unchanged, when the spraying distance changes, the electric field strength will also change. Therefore, the size of the spraying distance directly affects the thickness of the powder layer adsorbed by the workpiece and the deposition efficiency. The best distance is about 250mm.