Metal finishing Q&As since 1989

-----

Hard chromium plating is gray and rough

adv.    

March 12, 2008

I am a student at Papua New Guinea doing Industrial Training with a company who are specialised in hard chroming of Hydraulic cylinders & rods...

I think there's something wrong because after plating, it gives us grayish and a rough looking surface.

What do you think is wrong?

Zmesi Tairo
Student - Papua, New Guinea

---

Guess one would be a high content of trash metal ions. A second guess would be plating at a wrong amperage for the tank temperature.
Step one would be to get an analysis of the tank, probably using an AAS [on eBay or Amazon].

James Watts
- Navarre, Florida
March 14, 2008

---

Hi , sounds like you could be plating with excessive current - depending on size and shape of parts , the required current varies .

e.g., , a simple shape part such as a rod , with a surface area of 20 sq" , I would plate at 2 amps per sq".

and a small part , such as a bolt with a surface area of 1 sq" I would plate at 1 amp sq "

Also , check your solutions are up to the correct temperature , and stirred after being topped up , as the parts will look grey and burnt if vat is too cold .

hope this helps

Jay Smith
- Essex, UK
March 16, 2008

adv.