Problem in iron phosphating

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Sir, we are using passivated galvanized sheet for powder coating, and adopted the three tank iron phosphating online system for pre-treatment befor powder coating. We observe some problems which are very serious, these are as below:

1. No coating of iron phosphating was found on the components.
2. Sometimes heavy powdery coating and dust appeared on the components rather than iron phosphating coating.
our system is-
(1)Cleaner/coater bath (2% conc., pH- (1.5-3)BUT NOT SET, PRESSURE- 0.8 KG/SEQ.CM)
(11). water rinse(ordinary water) (PRESSURE - 1 KG/SEQ.CM)
(111). passivation-non chrome (3.5-5.5 pH)Ordinary water used

SO PL.Suggest the right parameters/system to get the `ok`iron phosphating coating on passivated galvanized sheet components on same line.

Thanks
Regards,

Arjun Singh
employee - Dehradun, India