Electrostatic spraying technology has become the core process to improve the efficiency of the manufacturing industry due to its excellent paint utilization, uniform coating and environmental protection advantages. By accurately controlling the spraying distance of 25-30cm, the voltage of 40,000-80,000 volts and the pressure of the spray gun of 0.55MPa, combined with the flexible adjustment of the external power supply spray gun, the paint loss can be reduced by 30%, and the zero leakage defects of metal parts can be realized, helping enterprises to build a green and efficient coating system.
In the field of equipment manufacturing, electrostatic spraying technology, as an advanced coating process, is increasingly widely used. With its excellent paint utilization, uniform coating quality and environmental advantages, it stands out from many industries and has become a key technology to improve product quality and production efficiency. The following will elaborate on the basic working principle of electrostatic spraying, the types and characteristics of electrostatic spray guns, and the key parameters of electrostatic spraying.
First, the basic working principle of electrostatic spraying
Electrostatic spraying uses the force of an electric field to achieve efficient transfer and adhesion of paint from the spray gun to the surface of the coated object. The grounded coating is used as the positive electrode, and the paint atomization device is the negative electrode, and the atomized paint particles are negatively charged through the energizing device, and an electric field is formed between the two electrodes. Under the action of electric field force, the negatively charged paint particles are quickly and accurately adsorbed to the surface of the coated object to form a uniform coating.
Second, the type and characteristics of electrostatic spray guns
1. Self-generating electrostatic spray gun
The self-generating electrostatic spray gun uses compressed air to drive a built-in micro turbine generator to generate electricity, and the generated electrical energy is raised to a high voltage of 40,000-80,000 volts through the boost module, providing electric field strength for the paint particles to be charged. The advantage is that it does not have to be connected to an external power supply, and it is suitable for scenarios where it is difficult to connect to the power supply or the spray gun needs to be moved frequently, such as field maintenance. However, the internal power generation device is precise, and the paint and solvent need to be strictly prevented from entering the power generation area during cleaning and maintenance, so as not to damage the air turbine generator and affect the normal operation and service life of the spray gun.
2. External power supply type electrostatic spray gun
The electrostatic spray gun with external power supply is the mainstream type, the gun body integrates a booster device, connects the external power supply to convert the voltage, and the spray gun atomization air pressure and current can be accurately adjusted through the electrostatic controller. The power separation of the spray gun has high safety, and the construction voltage can be flexibly adjusted according to the coating, the material to be coated and the coating requirements. For example, when spraying metallic paints, the voltage can be reduced to avoid coating defects. Moreover, the required atomization pressure is 0.10-0.15 MPa lower than that of the self-generating type, which is energy-saving and makes the spraying more stable and controllable.
3. Key parameters of electrostatic spraying
1. Spraying distance
The distance between the spray gun and the object to be coated should be 25 - 30 cm. If the distance is too close, the coating particles will arrive too fast, resulting in uneven coating thickness and accumulation and sagging; If the distance is too far, the electric field strength will be weakened, and some particles will not be effectively adsorbed, which will reduce the transmission efficiency, and make the coating leak and uneven thickness. For example, spraying the shell of small electromechanical equipment, the right distance can ensure that the coating thickness is moderate, the quality is excellent, and the corrosion protection effect and aesthetics are achieved.
2. Voltage control
The voltage affects the charge and electric field strength of the coating particles, which in turn determines the transmission efficiency and coating quality. Generally, the higher the voltage, the higher the transmission efficiency, but too high voltage will cause defects such as coating breakdown and pinholes. When spraying, it is necessary to adjust the pressure reasonably according to the type of paint, the material of the coated object and the distance between the spray gun and the coated object. For example, the metal material can be appropriately depressurized, and the plastic material can be appropriately pressurized.
3. Pressure limitation
The maximum supply pressure of the coating is not more than 0.7MPa, which is too high and difficult to fine and wasteful, affecting the quality, and too low and insufficient supply affects the spraying; The pressure of the compressed air should not exceed 0.7MPa, too high particles should disperse and pollute the environment, too low atomization is poor, and the appropriate pressure should ensure atomization; the pressure of the spray gun is generally not higher than 0.55MPa, and the high viscosity coating can be appropriately pressurized, and the low viscosity needs to be lowered to avoid excessive dispersion.
4. Paint ejection
The amount of paint sprayed should be controlled at 1/3-2/3 of the air spray gun, combined with the adjustment of the moving speed of the spray gun and the spraying area, the large-area spraying can be appropriately increased, and the detailed spraying can be reduced to ensure that the coating thickness is appropriate and avoid waste and defects.
With its unique advantages, electrostatic spraying technology is indispensable in the modern equipment manufacturing industry. Reasonable selection of spray gun type and precise optimization of operating parameters can improve coating efficiency, reduce costs and ensure coating quality. With the advancement of science and technology, electrostatic spraying will help the manufacturing industry to continue to develop in an efficient and green direction.
