In the manufacturing of wooden doors and decorative moldings, the efficiency and quality of the painting process directly determine the competitiveness of finished products. Traditional spray methods often struggle with low paint utilization, unstable curing results, and disjointed production flows when dealing with slender, irregular workpieces such as moldings and door frames. The automatic CNC spraying line dedicated to moldings and door frames addresses these challenges by integrating automated spraying, leveling, and UV curing technologies into a complete intelligent coating system.

This production line is not a simple assembly of separate machines but a highly coordinated coating system. It consists of three core units: an automatic spray painting machine for door frames and moldings, a leveling and flash-off conveyor, and a three-dimensional UV curing oven. Auxiliary equipment including feeding conveyors, dust removal systems, and air purification devices are also incorporated, creating a closed-loop process from raw workpiece entry to final cured coating.

The operational principle highlights the precision of numerical control. Workpieces are first smoothly transferred to the spraying station via a belt-positioning conveyor. An automatic dimension detection system scans the length and width of each workpiece in real time, and the data is processed by a CPU to precisely control the spray guns’ movement trajectory and paint output. This intelligent feedback mechanism ensures uniform, full-bodied paint films even at high conveying speeds, delivering both superior quality and mass-production efficiency.

2.1 High-Efficiency Paint Recycling and Utilization

Overspray and paint waste are common challenges in conventional spraying. This line is equipped with a paint recovery device that can reclaim 70%–80% of wasted paint, dramatically improving the actual utilization rate of coatings. This not only cuts material costs but also reduces waste disposal burdens, aligning with modern green manufacturing principles.

2.2 Segmented Curing in a Three-Dimensional UV Oven

To prevent cracking caused by excessive internal stress during rapid UV curing, the line features a segmented-curing three-dimensional UV oven. The staged curing process allows gradual stress release, effectively avoiding coating cracks. Moreover, the oven uses special-wavelength UV lamps that finely tune the toughness, hardness, adhesion, and sandability of UV paints. This ensures that the cured film offers optimal protection while still allowing easy post-treatment such as sanding or repair, if needed.

2.3 Seamless Integration of Dual Sprayers and Leveling Sections

The production line employs two sprayers working in tandem:

• The first sprayer applies a sealer or color coat. After spraying, the moldings enter a 6‑meter leveling and flash-off tunnel for solvent evaporation and film leveling.

• Once the base coat is tack-free, the second sprayer applies the topcoat, followed by a 12‑meter leveling tunnel for final leveling.

With the conveying speed precisely regulated by a frequency converter, the entire process from color coat to topcoat is completed in one continuous pass. This design eliminates secondary contamination that often occurs during intermediate handling, significantly boosting production yield and throughput.

Under increasingly stringent environmental regulations, this spraying line incorporates eco-friendly concepts throughout. The spray booth integrates a Taiwan-made control system along with a water-curtain purification unit, an exhaust system, and a pressure air system. The water curtain effectively traps paint mist, while the robust air extraction ensures a clean working environment – protecting operators’ health and helping emissions meet high standards.

Economically, the high‑recovery paint recycling unit and the energy‑efficient UV oven together reduce per‑unit energy and material consumption. Additionally, the precise curing control of the three-dimensional UV oven minimizes defects and rework, further strengthening the long‑term cost benefits of the line.