Process flow before spraying

At present, the process flow commonly used in most automakers’ coating automation lines is:

Hot water washing → pre-degreasing → main degreasing → spray washing → immersion washing → surface adjustment → phosphating → spray washing → immersion washing → passivation → circulating deionized water spray washing → circulating deionized water immersion → fresh deionization Water spray wash, a total of 13 process sections, usually a hand wipe before hot water wash. In general, the pretreatment can be divided into four parts: degreasing, surface conditioning, phosphating and passivation. There is a water washing process between the four to prevent impurities from being carried into the next process section to cause cross-contamination.

Application of bag filter before spraying

It is the key to improve the cleaning effect of multiple washings between various process sections before painting. Generally, the pollution control of the washing liquid is required to be less than 1/10 of the concentration of the treatment liquid in the previous process, that is, the purpose of dilution is 10 times. Under the requirements of improving water use efficiency and reducing cost, how to filter and reuse cleaning water and ensure the cleanliness of water quality is the key to the success of the filtration system. Secondly, the membrane filtration technology UF is used to recover the degreasing liquid, phosphating solution and regeneration. Highly polluted washing water and pre-treatment wastewater also place higher demands on the design and application of the filtration system.