Details about 4-tank phosphating process

A. Hi, Abhishek. There was a time when "the 3-tank process" and "the 7-tank process" had a universal meaning. Three steps was iron phosphating, seven steps was zinc phosphating, and there were that many standard steps. But with the change from final chrome rinses to either chrome-free or D.I. rinsing . . . with the change of integrating these pretreatments into electrophoretic painting lines . . . with the change of using accelerated, mixed, and tweaked phosphating baths: I don't think that there are any particular fixed steps, and "the 4-tank process" just doesn't mean anything. It could be an extended iron phosphate sequence; it could be a foreshortened zinc phosphating process.

Please tell us what you are doing and what your four steps are. Thanks.

Regards,

A. The people that you buy your chemicals from will be happy to tell you the main components in your tanks, what levels to maintain them and how to analyze the amounts.

A. Sir if you are using a shortened Zinc phosphating line then also desired results are achievable, you check your Total acid and free acid and write here in this forum, Ill tell you what to do next.

Also, please tell your 4 process. The ideal will be:

TANK 1 : DEGREASING/DERUSTING

TANK 2 : Water wash

TANK 3 : ZINC PHOSPHATING

TANK 4 : Water wash

While others will not approve the process, but it's just ok, if you are having all parameters correct.