Chassis Powder Coating Line

Process Flow Introduction of Chassis Powder Coating Line     

The chassis powder coating line is a complex and systematic production process that aims to provide a high-quality, durable, and aesthetically pleasing powder coating finish on chassis. The following is a detailed description of its process flow:

1. Incoming Inspection

Before entering the coating line, the chassis undergoes a strict incoming inspection. This includes checking for any surface defects, such as scratches, dents, or burrs. The dimensions and material quality of the chassis are also verified to ensure they meet the specified requirements. Only chassis that pass this inspection are allowed to proceed to the next step.

2. Pretreatment

2.1 Degreasing

The chassis is first placed in a degreasing tank or passed through a degreasing spray system. This step is crucial as any residual grease or oil on the surface can severely affect the adhesion of the powder coating. Alkaline or solvent-based degreasers are commonly used to remove contaminants. The chassis is immersed in the degreasing solution for a specific period, usually several minutes, and then rinsed thoroughly with clean water to ensure all degreaser residues are removed.

2.2 Phosphating (Optional)

Some chassis may undergo a phosphating process. The chassis is immersed in a phosphating solution, which reacts with the metal surface to form a thin phosphate layer. This layer not only improves the adhesion of the powder coating but also provides additional corrosion resistance. The phosphating process typically involves carefully controlling parameters such as temperature, concentration of the phosphating solution, and immersion time to ensure a uniform and effective phosphate coating.

2.3 Rinsing and Drying

After degreasing and (if applicable) phosphating, the chassis is rinsed again to remove any remaining chemicals. This is followed by a drying process, which can be achieved using hot air blowers or by passing the chassis through a drying oven. The drying step is essential to ensure a completely dry surface before powder coating, as moisture can cause defects in the coating.

3. Powder Coating Application

3.1 Loading onto the Conveyor

The dried chassis is carefully loaded onto a conveyor system that will transport it through the coating booth. The conveyor is designed to handle the chassis stably and at a controlled speed, ensuring a consistent coating process.

3.2 Electrostatic Powder Spraying

The chassis enters the powder coating booth, which is equipped with electrostatic spray guns. The powder coating material, a mixture of resin, pigments, and additives in powder form, is charged electrostatically as it is sprayed. The charged powder particles are attracted to the grounded chassis surface, resulting in an even and efficient coating. The spraying parameters, such as the voltage of the electrostatic charge, the distance between the spray gun and the chassis, and the powder flow rate, are precisely adjusted according to the size, shape, and coating requirements of the chassis. This ensures a uniform coating thickness and coverage.

4. Overspray Recovery

During the powder spraying process, some powder particles may not adhere to the chassis and become overspray. To minimize waste and environmental impact, an overspray recovery system is installed in the booth. The overspray is collected through a combination of cyclones and filters. The cyclones use centrifugal force to separate the larger powder particles from the air, and the filters capture the finer particles. The recovered powder is then sieved and recycled back into the powder supply system for reuse.

5. Curing

After powder coating, the chassis is transported into a curing oven. The curing oven heats the powder-coated chassis to a specific temperature range, usually between 150°C and 200°C, for a predetermined period, typically 10 to 30 minutes. The heat causes the powder particles to melt, flow, and cross-link, forming a hard, durable coating. The curing process is carefully controlled to ensure the coating achieves the desired hardness, gloss, and adhesion properties.

6. Cooling and Quality Inspection

6.1 Cooling

Once the curing process is completed, the chassis is allowed to cool. This can be a natural cooling process as the chassis is transported out of the curing oven and left to cool in a designated area, or it can involve forced-air cooling in some cases. Cooling is necessary to handle the chassis safely and to prevent any damage to the coating due to rapid temperature changes.

6.2 Quality Inspection

After cooling, the chassis undergoes a comprehensive quality inspection. This includes visual inspection for any coating defects such as pinholes, orange peel effect, or uneven coating. The coating thickness is measured using non-destructive testing methods such as magnetic induction or eddy current gauges to ensure it meets the specified standards. The chassis is also checked for any dimensional changes or damage that may have occurred during the coating process. Only chassis that pass the quality inspection are considered finished products and are ready for packaging and shipment.