Summary for electrochemical deburring and anodizing Discussion
electrochemical deburring and anodizing is the central issue in this thread: Joan Torra reports that some anodized aluminum parts show small bright areas where the anodize seems not to take, even though most parts are fine, and asks whether ECD can change the aluminum surface enough to prevent oxidation. The only direct answer in the excerpt comes from Manjunath S., who says hydrochloric acid or sulfuric acid can be used for this process, but he does not explain whether they should be added to the electrolyte or used afterward. Amir behagh later asks for clarification on that point, and Marc Green notes that the key unanswered question is what to do if ECD itself interferes with anodizing, aside from switching to mechanical deburring. The thread therefore raises a possible ECD-related surface problem, but the excerpt does not provide a confirmed root cause or a complete remedy.
Q. We machine aluminium parts that are anodized before final use. Before the anodizing, there is an electrochemical deburring process to burn specific areas to remove detachable burrs.
We have detected anodized parts (randomly in the batch) that show some areas of their surface where the anodizing hasn’t made any effect; and it seems to not be a problem of the anodizing process itself, because there are also a lot of good parts. It seems as if a little area of this surface can’t be oxidized during the process. The surface is external. After the anodization you can see clearly the brilliant aluminium.
My question is: Can the electrochemical deburring process alter the aluminium surface/nature to prevent the oxidation? How?
Joan Torra
3rd tier automotive – Sabadell, Barcelona, Spain
2004
A. Dear Sir,
You can use Hydrochloric acid or sulfuric acid for this process.
Manjunath S
– Bangalore, Karnataka, India
August 29, 2011
Q. Do we have to add these acids to the electrolyte, or after electrochemical deburring use them for chemical cleaning?
Amir behagh
– Isfahan, Iran
April 12, 2014
Q. I have a similar question, Amir. I appreciate Manjunath’s effort to help, but I don’t understand it :-)
If ECD does something to the aluminum which prevents proper anodizing, what are we supposed to do about it (other than use a different technology like mechanical deburring)?
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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April 2014
A. Ted,
It appears that the process makes the part to be de-burred anodic in an electrolytic solution. I suspect the burr removal also may cause the formation of an oxide film, that if not removed in the pre-treatment steps of the anodize process will interfere with the formation of the anodize.
Willie Alexander
– Colorado Springs, Colorado
April 22, 2014
A. I’m just going to speculate here, as I haven’t had to anodize anything that’s gone through an ECD process. But I think Willie hit the nail on the head when he states that perhaps an oxide is formed that must be completely removed prior to anodizing. I would think that the ECD process is somewhat similar in nature to electropolishing of aluminum, which will form an oxide, and will not anodize properly if not anodized immediately after electropolishing.
Marc Green
anodizer – Boise, Idaho
April 23, 2014