INCOMING CONTROL
The process begins with a thorough inspection of each coil to identify any physical damage or surface contaminants that could interfere with proper coating adhesion. Inlets and ports are securely sealed to prevent the entry of chemicals during processing.
CLEANING & RINSING
To ensure optimal E-coating adhesion, coils are thoroughly cleaned using an alkaline solution that removes dirt, oils, and other surface contaminants. Next is the rinsing process, which consists of two stages: an initial rinse in a heated solution, followed by a second rinse at ambient temperature.
EPOXY PAINT DEPOSITION
Coils are fully immersed in a water-based epoxy paint bath, where an applied electrical current drives the uniform deposition of paint particles onto the aluminum surface through electrophoresis. Kaltra utilizes a cathodic electrocoating system, in which the heat exchanger acts as the negatively charged electrode, attracting positively charged paint particles.
To ensure complete and consistent coverage, several critical parameters are precisely controlled throughout the process:
- Voltage and current levels
- Bath composition and paint formulation
- Immersion duration
POST-RINSE
After deposition, the coils are rinsed to remove any loose or excess paint particles. A final rinse using deionized water ensures a smooth, uniform coating surface and prepares the parts for curing.
COAT CURING
Coils are transferred to a baking oven, where the epoxy coating is crosslinked and cured at temperatures ranging from 80°C to 240°C, depending on the specific paint formulation. Proper curing is essential to achieve maximum coating durability, mechanical strength, and resistance to environmental stress.
UV-RESISTANT TOPCOAT
Epoxy-painted surfaces tend to deteriorate when exposed to direct sunlight, so a UV-protective topcoat is applied using a spray gun to ensure long-term durability.
HELIUM LEAK TEST
After the coating process is complete, each coil undergoes a helium leak test to verify its integrity and ensure that no damage occurred during processing.
