Over Phosphating Metal Parts

[cmwatson78]

We are phosphating metal parts to apply an ahesive and primer. I cant give to much info. Is the pH of the phosphate an issue? We are ok with the concentration, but we are thinking its the metal of the parts. can that be the case?
The tops of the parts are fine, but the bottoms are being over phosphated. I am thinking it has to do with the rinse being too hot and the spray not working. Could this be the case?

 

[ck1999]

The overphosphating of the parts could come from lack of rinsing and drying time in combination. Yes, pH plays a role in phosphating.
Not sure what you mean by "we are thinking its the metal of the parts"?

When you say bottoms are you meaning the bottom part of a vertical surface or the underside of the part?

Have you cleaned your nozzles lately in your phosphate and rinse stages?

What is the temperature of the phosphate stage, rinse stage? Are you using a dry off oven?

ck1999