Summary for surface finish is roughened by phosphating Discussion
Surface finish is roughened by phosphating because the coating is meant to create tooth for paint, retain oil, and provide a break-in surface, so it will not look like a polished machined finish. In this thread, Anil Jadhav asks how to keep the same machined finish on ball valves after manganese or zinc phosphating, and whether there is an alternative rust-prevention process after testing. The reply explains that phosphatizing is expected to roughen the surface, so the finish cannot be preserved in the same way. As a possible alternative, electroless nickel plating is suggested if a polished appearance is required. The answer also cautions that the real issue may be the specification itself rather than the phosphating process, implying the finish requirement may need to be reconsidered.
Q. We are facing problem of disturbing the surface finish by Manganese or Zinc phosphating. We require the same surface machined finish after phosphating. What will be the process for the same? Is there any alternative process to Phosphating? We are doing it for the rust prevention of our ball valve after testing.
Anil Jadhav
manufacturing Manager in valve industry – Pune Maharashtra India
October 29, 2009
A. Hi, Anil. Phosphatizing is supposed to roughen the surface, to provide tooth for painting or to hold oil for improved dry running, and to serve as a break-in surface. You can’t ask it to read as if it were a polished machine surface.
If you need a polished surface, you could try electroless nickel plating … but are you sure that the phosphated surface is the actual problem rather than your spec needing correction? 🙂
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Q. Want to do phosphating on machined components used in hydraulic cylinders.
Q1: Is it advisable to do phosphating on hydraulic oil seal groove surfaces along with all the other surfaces of the component? Will this process affect the surface finish required for oil seal groove?
Q2: After Phosphating the seal groove dimensions will change and affect the seal performance? if So then is it necessary to machine the parts with space for costing layer thickness?
Ramamoorthi chellappa
Hydraulics – Bangalore, India
July 6, 2019