Analysis and solution of the problem of different color particles in the spra...

Analysis and solution of the problem of different color particles in the spray gun spraying the car body finish!

There are more or less problems when we spray products with paint spray guns. Today we will analyze some of the problems that occur when spraying cars!

1. On-site situation

The spraying process of spray gun topcoat is: manual blowing and cleaning of topcoat → manual spraying of solvent-based color paint with electrostatic spray gun → manual spraying of solvent-based color paint with air spray gun → flashing of color paint → manual spraying of external surface solvent-based varnish with air spray gun → manual spraying of solvent-based paint on the outer surface with air spray gun Spraying solvent-based varnish on the inner surface → manual spraying of solvent-based varnish on the outer surface with an electrostatic spray gun → leveling → drying.

2. Problem description

A large area of black particles appear on the body after the finish paint on the trimming station, especially the white body is the most obvious. It cannot be removed after sanding with P2000# sandpaper, and the base paint is exposed after deep sanding. Seriously affect the workshop production rhythm. A 100x magnifying glass was used to observe the polished part on site. Preliminary analysis showed that the particles were caused by environmental pollution in the wet film state after varnish spraying, but the exact composition and source of the particles could not be determined.

3. Troubleshooting

1) According to the above situation, firstly observe whether there are different color particles on the body after the paint is sprayed. After observation in the spray booth, the car body after the paint spraying was not found to have abnormal color particles before entering the varnish spray booth, and the car body after the varnish spraying was found to have 2 different color particles before entering the drying furnace lift. Then mark the position of the different-colored particles. After the topcoat is dried, track the car at the modification station to find black particles on the large topcoat of the body. After grinding the marked two different-color particles, it was found that the different-color particles here were eliminated after grinding. However, the discolored particles in other positions still cannot be eliminated by grinding. From this, it is preliminarily judged that the cleanliness of the topcoat drying lifting section or the drying furnace is poor, resulting in different color particles on the car body after the topcoat.