HOME FAQs BOOKS JOBS: Help Wanted Suggestions you are here: Hotline/Forum => Letter 19316
1B Anodize setup questions
+++
We are working to install a Mil-A-8625 [link is to spec at TechStreet] Ty 1B Chromic Anodize bath.
1. Are Teflon heaters generally used during cold weather?
2. Are Aluminum Cathodes recommended?
3. Are Titanium coils OK, or are plate/frame heat exchangers more common. We have heard that both could leak acid into the chiller fluid.
What are your thoughts?
John McGuirk- Oldsmar, Florida
+++
Teflon heaters would be fine but, because the anodizing process usually runs at 68 to 72 degrees F. (room temperature), and the rectifiers provide plenty of heat in operation, few installations have heaters.
Most, but not all, people feel that aluminum cathodes are the way to go because of energy savings.
Titanium coils are okay, as are external heat exchangers. Both are widely used. But because both localized cooling and localized agitation are required, I believe that external heat exchangers are gaining dominance.
|
 Ted Mooney, P.E. finishing.com Brick, New Jersey |
+++
You can use steel cathodes in chromic acid anodizing, you can even use the steel tank for the cathode.I have never heard of using aluminum cathodes in chromic anodizing.
The titanium might introduce a bipolar or galvanic stray current,so if you do use titanium tie it (connect it)to the cathode side. Teflon would be better.
Like Mr Mooney said, especially in Florida, you do not need a heater unless you are somewhere around the latitude of Jacksonville, and then only on Monday morning.
|
Robert H Probert Robert H Probert Technical Services  Garner, North Carolina
|
+++
I didn't read the question, did I? I was sure it said sulphuric acid anodizing, but it obviously doesn't :-)
|
 Ted Mooney, P.E. finishing.com Brick, New Jersey |
++++
We have an existing process line and chromic anodize per Mil-A-8625 [link is to spec at TechStreet]. We presently use lead cathodes on aluminum hooks which are suspended along the sides of the tank from bus bars. The connections between the hooks, cathodes, and bus bar require extensive cleaning to maintain conductivity. Is there a better type of cathode that would be more reliable and less labor intensive.
Michael DalleoAerospace - Bloomfield, Connecticut, USA
November 29, 2008
Hi, folks. The subject of cathode material for chromic acid anodizing has come up repeatedly. So, for more insights see letters 524, 26783, 35181 and 39329.
Regards,
|
|
Ted Mooney, P.E. finishing.com Brick, New Jersey |