Q:How to control surface cleanliness and roughness?
A:Rust and oil removal: Use sandblasting or shot blasting to treat the metal substrate to thoroughly remove scale, rust and oil stains to ensure surface cleanliness. The roughness is controlled at 40-75μm (such as steel structure). Too low roughness will lead to insufficient coating adhesion, and too high roughness will easily cause uneven thickness (thin coating in concave areas).
Fill defects: For defects such as welds, holes, scratches on the surface of the substrate, fill and polish with putty or repair paint first to ensure a smooth surface.
Q:How to ensure stable coating performance?
A:1. Viscosity and aging control
Adjust the viscosity according to the paint instructions (e.g., the viscosity of air spray should be controlled at 15-25s. If the viscosity is too high, it will easily lead to poor spray atomization (thick edges, piled materials), and if the viscosity is too low, the risk of sagging will increase.
Two-component paints must be mixed strictly according to the proportion and left to mature for 10-20 minutes (e.g., insufficient aging time for epoxy paint will lead to uneven curing and affect the stability of coating thickness).
2. Filtration and stirring
Before use, the paint needs to be filtered with a 120-200 mesh filter to remove impurities and lumps to avoid nozzle clogging or particle accumulation during coating (e.g., powder coating needs to ensure that the powder particle size is uniform, 80-120 mesh is recommended).
Paints stored for a long time need to be fully stirred (mechanical stirring ≥5 minutes) to prevent pigment sedimentation from causing differences in viscosity and solid content between the upper and lower layers.
Q:What are the key points of equipment maintenance?
A:Regularly calibrate spraying equipment (such as flow meters, pressure gauges) to ensure parameter accuracy (error ≤ ±5%). Replace nozzles when wear exceeds 0.1mm (for example, after the aperture of the air spray nozzle is enlarged, the atomized particles of the paint become coarser, resulting in uneven thickness).
The automatic coating line needs to clean the nozzles and feed pipes regularly to prevent the paint from solidifying and agglomerating and affecting the flow stability.
Q:How to control temperature and humidity?
A:The construction environment temperature is controlled at 5-35℃, and the humidity is ≤85%. In low temperature environment, the paint dries slowly and is prone to sagging (winter thinner can be added); in high temperature environment, the solvent evaporates quickly, and the coating is prone to orange peel or uneven thickness (slow-drying solvent can be used). ◦ When the humidity is greater than 85%, water vapor is easily condensed on the surface of the substrate, and construction needs to be suspended or dehumidification equipment needs to be used (such as the dew point temperature is more than 3℃ lower than the surface temperature of the substrate).
Q:What is the core logic of uniformity control?
A:The uniformity of coating thickness needs to be achieved through the whole process control of "standardized substrate processing + coating performance adaptation + precise equipment debugging + standardized operation + real-time detection feedback". For high-demand scenarios (such as aerospace and marine engineering), it is recommended to use automated spraying equipment + online detection system, while manual construction scenarios require enhanced operator training (such as passing the wet film thickness gauge use assessment) and establishing a strict three-inspection system (self-inspection, mutual inspection, and special inspection). Through multi-dimensional collaborative optimization, the coating thickness deviation can be controlled within ±10%, meeting most industrial anti-corrosion needs.