Manganese PHOSPHATING process

I am looking for any suggestions regarding manganese phosphating process in dipping mode. We use this treatment on pieces with these characteristics:
MATERIAL: CAST IRON
SURFACE : Pieces are finished with ground and brushed areas.
ROUGHNESS : Rz between (2 : 3) micron

We want to obtain a constant and uniform phosphating layer between 0.0005 - 0.0015 mm

The cycle is this one.

1)Degreasing.
2)Degreasing with ultrasonic waves.
3)Rinse.
4)Rinse
5)Activation
6)Phosphating Mn
7)Rinse
8)Passivating
9)drying up
10)stripping
11)cooling

We want to use a ultrafiltration system for phosphating bath in order to not have sludges. Is it correct? Or is it necessary to have a certain quantity of sludges to get the chemical stabilization of the bath? The bath must be in an agitated mode (using a pump) or in sedate mode? Which kind of filtration process with easy management do you suggest?

Best Regards
Thank you for answering,

Your cycle looks good to the extent that I can interpret it.

Step 5, you call "activation" is not an acid, but a "grain refiner".

Control the total/free acid to 7/1,adjusting immediately before starting to process. Bring the buret to the tank. (IT WILL NOT WORK TO SEND THE SOLUTION TO THE LAB AND WAIT TWO DAYS AS THE T/F CHANGES continuousLY). Start heating. When you get to 185 °F, do the total free titration and adjust immediately with Manganous Carbonate, by the time you do that you will be at 195 °F, start coating. I prefer 195 to 205 °F.

Dear Sir,
I came across your enquiry regarding Manganese Phosphating. If you could send the details of the job and the process involved, we may be able to provide a solution to your problem.

Ed. note: What additional job and process details should he post before you are able to offer any technical suggestions, Mr. Kulkarni? Thanks.

Dear Sir,
I found defect in Manganese phosphating surface treatment.
The defect colour is Brown.
Quality Engineer said this defect because of HCl react with Manganese coating .
I kindly request you to send the reason for the defect and Effect of the defects.

Hello, Manimaran. I may not be understanding your question but the QC engineer who is there told you what he thinks happened; we can't confirm or deny his assessment, from thousands of miles away, based on a verbal description of the color.

As for the effect of defects, please don't try to predict all the scenarios scenarios of "what could happen if". A defective finish is a defective finish and must be rejected. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Dear Sir
I am doing manganese phosphating on shaft material is 20MnCr5 & Surface Finish is 0.4 Ra but after phosphating surface roughness comes to 0.56 to 1.2 Ra & Plating thickness is 5 to 8 micron. Pl. Tell me the reason behind that.