The authoritative public forum
  for Metal Finishing since 1989
-----

Electroplating Peels Off Aluminum Extruded Sections

Dear sir,
We are manufacturers of aluminum extruded sections based at Vadodara, Gujarat, India and we have some problem. We extrude the section in 6063 alloy having silicon 0.4%, Magnesium 0.5% and Iron 0.15%. These sections goes for electroplating. After chrome plating the plating gets peeled off, hence our sections gets rejected. Please tell us what is the basic problem we face also any elements ratio we have to increase. Also we want to know what should be the surface finish of the extruded section for the same.

With best regards,
Rao,

Gundu Rao
In charge of the manufacturing shop - Gujarat, India
February 25, 2010

Hi, Rao. Speaking only in vague generalities, the problem is probably that the plating shop is not doing proper zincating. Aluminum is not directly electroplateable, so the process starts with an immersion plating process in zincate solution, and this requires careful attention and is often problematic.

But realistically, the plating shop must solve this adhesion problem or you must find a different plating shop. The idea that a third party (who has not seen either the parts or the process) can explain to a second party (who doesn't have expertise in electroplating) how the first party can fix a highly technical problem isn't very realistic :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 25, 2010

---

Hi,

On extruded aluminium the alloy elements will be changed in order and the alloy doesn't have the same alloy elements like the spec in same aluminium batch. It's difficult to make the same pretreatment steps for all aluminium parts in the same batch. Time in the pretreatment steps can be changed for parts in same batch and its not the same for al parts. Also the storage for the Aluminium batch is important.

I hope this can help you to understand how difficult it is to plate on extruded aluminium.

Regards

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
March 13, 2010