a. After thinning the topcoat, stir it evenly, filter it with a 180~200 day fine screen or 3~4 layers of gauze, and the viscosity meets the process requirements.
b. Correctly select coating equipment according to the characteristics of topcoat materials, process requirements and characteristics of coating machinery.
c. The place where the topcoat is applied and where it is dried should be clean and dust-free. For occasions with high decorative requirements, the topcoat should be applied in an air-conditioned spray booth to ensure that the coating surface is free of cilia, particles and has good flatness.
The process flow of oil tank spraying finish paint is as follows:
Undercoat inspection → concealment → dust removal, → manual, air or electrostatic spraying of aluminum powder coating → correction → drying → manual, air or electrostatic spraying of transparent red paint → correction → leveling → film curing → cooling → inspection → decals →Single light.
For electrostatic coating, the Ω automatic electrostatic coating line is generally used, and the spraying process parameters are as follows.
Acrylic or polyxiyan aluminum powder paint, transparent red paint, etc., the resistance is 5~50Ω, the construction viscosity is 15~25s (coat a 4-cup viscometer, 25°C), the number of workpiece rotations is 3~4 times, and the chain speed is 1.5~ 2.5m/min, the disc speed is not less than 3000r/min, the working voltage is 80~-90kV, the lifting speed is 5~25m/min, the working current is 80~120µA, the number of spraying is 6 times, the indoor temperature is 25℃, and the relative humidity is 70 %, the distance between the workpiece and the disk is 200~300mm, and the drying and curing conditions are 140~150℃ for 30min.
The decal is to finely polish the surface of the fuel tank with 800 # ~ 1000 # water sandpaper after the topcoat is painted. After grinding, it should be flat and smooth, and defects such as sandpaper lines and exposed bottom are not allowed. Use a special scribing board for oil fill that has been polished and qualified, draw a line at the designated position on the west side of the oil fill, pay attention to the clear and accurate lines, and do not allow scratches on the coating film. Unfold the hard paper at one end of the color strip, align the side coated with the adhesive with the position of the oil filling line, and paste it while squeezing it until it is flat and pasted. The position of the color strip needs to be pasted accurately, no wrinkles, air bubbles, etc. are allowed, otherwise it should be re-pasted or corrected with a steel needle.
In order to protect the color paint layer (or decals) and improve the gloss and decoration of the top coat, the last step of the top coat is to apply varnish. This process is called single light. Oil refill single light usually uses two-component polyurethane varnish or ultraviolet light curing uv varnish single light. Here is a brief introduction to the construction process of uv coatings.
The bottom surface of the fuel tank is coated → drying → grinding → dust removal, → spraying uv varnish → (infrared) leveling → uv curing → inspection.
