The specific process flow of Dakro processing technology is as follows:

Degreasing: The surface of workpieces with grease must be degreased to ensure the adhesion and corrosion resistance of the coating. There are generally three methods for degreasing, namely organic solvent degreasing, water-based degreasing agent degreasing, and high-temperature carbonization degreasing.

Rust removal and deburring: Workpieces with rust or burrs must undergo a rust removal and deburring process, which is best carried out using mechanical methods to avoid acid washing to prevent hydrogen embrittlement, as acid washing can affect the corrosion resistance of the Dacromet coating.

Coating: Clean workpieces that have undergone oil and rust removal should be surface coated as soon as possible through immersion coating, spraying, or brushing. During the coating process, the density, pH value, viscosity, Cr content, temperature, and flow condition of the coating solution directly affect the coating effect and various properties of the workpiece. Therefore, it is necessary to adjust the relationship between temperature, solution indicators, and centrifuge speed during immersion coating.

Pre drying: Workpieces with Dacromet wet film must be pre dried at a temperature of (120 ± 20) ℃ for 10-15 minutes as soon as possible to evaporate the moisture in the coating solution, allowing the coating to level and fix on the surface of the workpiece.

Sintering: The pre baked workpiece must be sintered at a high temperature of around 300 ℃ for 20-40 minutes, or the temperature can be appropriately increased to shorten the sintering time. At this stage, some hexavalent chromium undergoes oxidation-reduction reaction with ethylene glycol at high temperature, becoming trivalent chromium. The mixture adheres flake like zinc and aluminum to the surface of the metal substrate, while also serving as a bonding agent between zinc and aluminum layers, forming the final coating and improving the corrosion resistance and adhesion of the coating.

Cooling: After sintering, the workpiece must be thoroughly cooled by a cooling system before subsequent processing or finished product inspection. If the cooling is uneven or too fast, it may cause problems such as cracks or detachment of the coating.

For some workpieces with special requirements, secondary spraying and baking may be necessary to increase the coating thickness and further enhance corrosion resistance.