Fully Automatic Coating Assembly Line - Electrostatic Powder Spraying Unit

Fully Automatic Coating Production Line - Electrostatic Powder Coating System

135 Shandong 0543 Bright Light 2698 Coating

Product Overview: Electrostatic powder coating is currently one of the fastest-growing and most important application processes in powder coating technology. The basic principle involves creating a high-voltage corona discharge field between the spray gun and the workpiece. When powder particles are ejected from the nozzle and pass through the discharge zone, they capture a large number of electrons, becoming negatively charged particles. Under the influence of electrostatic attraction, the powder coating is sprayed onto the surface of the workpiece and adheres to the positively charged substrate. When the powder accumulates to a certain thickness, the "like charges repel" effect occurs, preventing further adhesion. Due to electrostatic forces, the powder is evenly adsorbed onto the workpiece surface, forming a powdery coating. This powdery layer is then cured through high-temperature baking, leveling, and solidification, resulting in a final coating with various effects. The喷涂效果 (spraying effect) outperforms traditional painting processes in terms of mechanical strength, adhesion, corrosion resistance, and aging resistance.

Process Flow: The typical electrostatic powder coating process is as follows: Loading → Degreasing → Rinsing → Derusting → Rinsing → Phosphating → Rinsing → Passivation → Electrostatic Powder Coating → Curing → Cooling → Unloading
Spraying Distance: Spraying distance is a key parameter controlling coating thickness, generally maintained between 10~25 cm from the workpiece, depending on the spray gun type.
  Electrostatic powder coating equipment mainly includes: powder spray booth, high-voltage electrostatic generator, electrostatic spray gun, powder feeder, powder recovery unit, workpiece rotation mechanism, etc.
Coating Process:
I. Surface Pretreatment:
The quality of pretreatment directly affects the quality of the powder coating film. Poor pretreatment can lead to issues such as film peeling and blistering. Therefore, pretreatment must be taken seriously.
(1) For sheet metal stampings, chemical pretreatment methods can be used: degreasing → derusting → rinsing → phosphating (or passivation). For heavily rusted or thick-surfaced workpieces, mechanical methods like sandblasting or shot blasting are employed for derusting.
(2) Applying putty. Conductive putty is applied based on the extent of workpiece defects. After drying, it is sanded smooth before proceeding to the next step.
(3) Masking (also known as covering). Areas where coating is not required are covered with masking tape or similar materials before preheating to avoid coating application.
(4) Preheating. Generally not required. If a thicker coating is desired, the workpiece can be preheated to 100–160°C to increase coating thickness.
II. Coating Application:
The workpiece enters the spray booth via a conveyor chain, positioning it for coating. The electrostatic generator releases high-voltage static electricity (negative electrode) through the electrode needle at the spray gun nozzle toward the workpiece space. The mixture of powder and compressed air ejected from the nozzle, along with the surrounding air, becomes ionized (negatively charged). The workpiece is grounded through the conveyor chain (ground electrode), creating an electric field between the gun and the workpiece. Powder is propelled to the workpiece surface by both electrostatic force and compressed air pressure, forming a uniform coating through electrostatic attraction.
III. Baking and Curing:
After coating, the workpiece is conveyed into an oven at 180–200°C for heating and held for a specific duration (15-20 minutes) to melt, level, and cure, achieving the desired surface effect. (Different powders require varying baking temperatures and times.)
IV. Cleaning.
After the coating cures, remove any masking materials and smooth out burrs.
V. Inspection:
For cured workpieces, routine inspections focus on appearance (smoothness, gloss, presence of particles, pits, etc.) and thickness (controlled between 55–90 μm). Workpieces with defects such as missed spots, pinholes, scratches, or bubbles are repaired or recoated.

Shandong Bright Light Coating Technology Co., Ltd. was established in 2001, with its headquarters located in Zouping County, Binzhou, Shandong. It evolved from the former Zouping Coating and Paint Booth Manufacturing Plant and was officially registered in 2008. The company specializes in the production of large-scale paint spraying and drying equipment, sandblasting rooms, powder coating room recovery systems, box-type curing ovens, water curtain cabinets, and other surface treatment equipment. Heating methods include fuel oil, electric heating, steam, and more. The product line covers industrial coating, high-low temperature equipment, constant temperature and humidity spray booths, and provides spray line design and installation services. The company's new factory spans 17,000 square meters and is equipped with large production machinery such as CNC shearing machines and bending machines, forming an integrated R&D, production, and installation service system.