1. The foreign matter (oil and ash) of the electrophoresis line is mixed in the bath, and the oil floats on the surface of the electrophoresis bath or emulsifies in the bath.

2. The coated object is contaminated by foreign matter (such as dust, lubricating oil falling from the conveyor chain, oily iron powder, paint dust immiscible with electrophoretic paint, oil in the compressed air for drying, environmental pollution when the wet film is dried) .

3. Poor pretreatment degreasing and oily phosphate film.

4. Foreign matter (oil and dust) is mixed into the cleaning fluid of the electrophoresis line.

5. The drying furnace is dirty or the circulating air contains oil.

6. The poor quality of deionized water makes the water-replenishing coating poorly soluble in water.

Prevention and control methods:

1. The oil tank liquid circulation system should be equipped with a degreasing filter bag to remove dirt and remove the oil on the liquid surface of the auxiliary oil tank in time.

2. Adhere to clean electrophoresis line equipment, clean the conveyor chain (plan to avoid dripping of lubricating oil) and hanging tools, use oil-free compressed air to avoid dust, other paint mist and oil from falling on the painted workpiece. Petroleum pollution is not allowed. Partition walls are provided at the contact section between the workpiece and the environment before and after electrophoresis.

3. Strengthen the pretreatment and degreasing process to ensure that the phosphating membrane is pollution-free.

4. Adhere to the washing water quality after electrophoresis and strengthen the filtration of the washing liquid. The corridor should be reinforced between scouring and drying.

5. Keep the electrophoresis line drying room and circulating hot air clean.

6. Strictly control the quality of deionization for dilution to ensure that the electrophoretic paint is soluble in water and filtered into the tank.