An Exploration and Analysis of Ten Questions Surrounding the New Transformation in Coating Technology

Huicong Surface Treatment Network:

1. What is coating?

The coating flows from the coating reservoir above the spray-coating machine through the spray blade, forming a continuous and uniform coating film. The workpieces are fed onto a conveyor belt and pass beneath the spray blade, where their surfaces are evenly coated with a layer of paint. Any coating that does not adhere to the workpieces is collected by a return trough and returned to the coating hopper, from where it is pumped back to the coating reservoir for recycling.

2. What are the different drying methods for coating by spraying?

Coating methods include four types: ambient-temperature drying, oven drying, microwave drying, and UV ultraviolet light drying.

3. What types of paints are used for spray coating?

It can be used to apply PU paint, PE paint, NC paint, UV paint, and water-based paint.

4. What are the components of a spray coating system?

The first type of intermittent PU coating line design includes: a self-conveying double-sided vacuum dust removal machine, a 7-meter Class 100,000 cleanroom for wet coating, a Class 100,000 drying chamber for wet-coated surfaces, and a dust-free curing chamber (which can also be designed as a 15-meter microwave-assisted curing tunnel with enhanced drying capabilities).

The second type of fast-drying PU coating line design: self-conveying double-sided vacuum dust removal machine, 7-meter Class 100,000 cleanroom for coating application, 45-meter defoaming and leveling tunnel, 45-meter low-power microwave tunnel for solvent evaporation and initial drying, 15-meter high-power microwave drying tunnel for final curing, and 5-meter cold-air cooling and packaging section.

The third type of production line features a rapid drying system for water-based coatings: a self-conveying double-sided vacuum dust removal machine, a 7-meter Class 100,000 cleanroom for spray coating, a 45-meter low-power microwave tunnel for initial evaporation and drying, a 15-meter high-power microwave drying tunnel for thorough curing, and a 5-meter cold-air cooling and packaging section.

The fourth type of pipeline rapid-drying UV coating spray design includes: a self-conveying double-sided vacuum dust removal machine, a 7-meter Class 100,000 cleanroom for dust-free spraying, a 45-meter low-microwave defoaming and leveling tunnel, a 3-meter UV dryer, and a packaging section.

The 100,000-level spray coating booth is equipped with a volatile solvent extraction tower, positive-pressure ventilation, a spray coating machine, and a paint-mixing area. The air particle standard requires particles smaller than 10 microns.

5. Where can coating application be used?

Dip coating is used for coating flat workpieces with a height of 10 cm or less. It is widely employed in decorative coatings for industries including door manufacturing, panel furniture, kitchen cabinets, flooring, moldings, decorative glass, new eco-friendly building materials, printing, shutters, large-format digital printing, handicrafts, calcium silicate boards, ecological wood panels, and integrated exterior wall insulation and decoration systems.

6. What are the benefits of coating by spraying?

The coating application methods include: curtain coating, spray coating, brush coating, roll coating, and dip coating. Curtain coating is an environmentally friendly method that saves labor, reduces paint consumption, is fast, produces excellent mirror-like finishes, and delivers good hole-opening effects. However, curtain coating can only be used on flat workpieces, which is its main limitation.

Lindu Development is growing very rapidly.

Table 1: Comparison of Advantages and Disadvantages of PU Coating vs. PU Spraying

Features: PU coating with PU spray provides a good mirror-like finish—generally satisfactory. It also delivers excellent orange-peel texture and uniform, easy-to-achieve pore formation. This method significantly reduces labor costs by three times compared to traditional professional spray painting, making it ideal for operators and handlers.

Saves paint consumption with virtually no waste—approximately 50% less waste. Five times faster operation. Saves space—occupies less floor area. Uses 10 times less electricity. Produces zero wastewater—no water curtain system, no sewage, no paint mist. No PM2.5 emissions. Highly improved working environment. No hazardous paint sludge generated.

Emissions are reduced by a factor of two, with an investment of 280,000 (dust removal unit + spray booth + spray coating machine) and 450,000 (one spray booth equals nine oil booths). Spray guns + water curtain booth + drying room + air pump—easy to recruit workers, but oil painters are hard to find. Can we handle irregular-shaped parts? Yes, we can.

7. What factors determine the surface appearance of liquid-coated coatings?

a. Coating quality for spray application;

b. Precision of the coating knife on the coating machine;

c. Operational control of process parameters during curtain coating, including coating viscosity, conveyor belt speed, and the width of the bottom gap at the discharge port of the coating machine.

d. Dust-free level of the coating booth

e. Dust removal performance of the double-sided vacuum dust collector

8. What conditions must be met for the construction of a dip-coating line, and what types of paints can be used in dip coating?

1. The furniture must be made of flat-panel materials.

2. The coating capacity is substantial—a coating crew of six can coat more than 1,000 square meters per shift, and at the end of each month, the area requiring primer and topcoat applications exceeds 10,000 square meters.

3. The coating machine can apply PU primer, PU topcoat, PE white primer, PE clear primer, NC primer, NC topcoat, base color touch-ups, UV coatings, and water-based coatings. It can produce open-matte effects, fully enclosed matte effects, and high-gloss mirror finishes.