The authoritative public forum
  for Metal Finishing since 1989
  

  -----

More information about hard anodizing of interior tubes

2003

Dear Sirs,

I want some information about equipment for hard anodizing of interior tube (such as suitable anode, contacts, solutions, rectifiers, etc.). Also for anodizing the outside of this tube what do we work for protection of inside ?

Best Regards,

Shapour Abd Sharif Abadi
automotive - Tehran, Iran

---

2003

You will need at least a couple of books, if not a consulting engineer, Mr. Abadi. Hard anodizing is quite a deep subject, not a matter of reading a paragraph or two about how to do it. But the anodizing step itself is conducted at about the freezing temperature of water in a 10 percent solution of sulfuric acid, and requires about 50 volts minimum. Anodizing the inside of a tube is more difficult since you need to get a cathode in there as well as solution replenishment and a way to purge any build up of hydrogen or other gases.

I'm not sure that I understand your final question, but it may be best to anodize the inside and outside of the tube simultaneously.

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