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2024 Aluminium Hard Anodize Problem
--I would appreciate any help/information in regards to hard anodizing 2024 T3 aluminium to Mil-A-8625 [link is to spec at TechStreet] Type III black.
We are having a problem on some specific parts in which we are attempting to get a minimum of 1.2 mil applied to a bore on a machined part. The part is 5.000 inches OD by 4.250 inches long with a bore diameter that has steps in it from 1.9750 inches to 2.120 inches. Our tank temperature is 57 degrees F, aluminum content 1.0 , bath concentration 25.9 oz. per gallon. We were applying 16 volts with a initial amperage of 1100 amps.
Richard Johnson
--Sir,
2024 is a hi copper alloy & cannot be hardcoated in conventional hardcoat systems. Here in our facility we use 2 different hardcoat systems, Martin HC & Imperv-X HC. Martin will process most alloys BUT NOT hi copper ones. The Imperv-X system is specifically designed for high copper alloys and we hardcoat them daily with no problems.
David A. Kraft
- Long Island City, New York
--Richard,
Your information is not complete which makes an answer difficult or at least required an assumption to be made which is not good.
Al 1.0 Oz/gal or g/l or? Sulfuric Acid Oz by weight or fluid Oz ?
Normal hard anodize is 32 deg F. Are you using a proprietary or an additive? Straight DC or superimposed AC or pulse?
The high copper content in your alloy makes the anodizing more difficult, but you should be able to get 1 mill.
If your final voltage is 16, you are hard pressed to call it type III anodize, and 1 mil will be very hard to get.
Include all of the process variables and it will be easier for people that are more knowledgeable than me to help you.
Jim
James Watts
- Navarre, Florida
--Your processing parameters are more appropriate for an anodize than a hardcoat. I doubt that this coating would meet the minimum wear requirements for a Type III hardcoating per MIL-A-8625. This could be contributing to your difficulties in achieving the desired thickness. Typical hardcoat anodizes utilize higher voltages and current densities with lower solution temperatures. The trade-off for these harder, thicker coatings is an increased tendency for "burning", particularly in the 2XXX series alloys. Special procedures and process controls can help minimize this phenomenon. Also, proper design and placement of auxiliary cathodes will help with coating uniformity.
Chris Jurey, President IHAA
Luke Engineering & Mfg. Co. Inc.
Wadsworth, Ohio
++
Dear Reader,
Hello. I am a searcher about "hard anodizing in ambient temperature". Please if you have a article or book about this, send me.
Thank you,
Mehdi Khandan- Qom, Iran
----
Ed. note: Please visit our Amazon index for a list of books on this subject. Some people call this "Type 2-1/2 anodizing"; additives are employed to allow quasi-hardcoating at the temperatures usually used for conventional Type 2 sulfuric acid anodizing.
July 16, 2009 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Hello my name is Jake Allen and I am 21 years old. I work for a plating shop in Grove, Ok.
We have recently been sent parts that are 2124 aluminum. The parts are to be hard coated. We have attempted to process a few and some of them come out ok but we have had a few burn. We have good contact and our acid and alumina content are good. Our sulfuric content is 360-390 g/l and alumina is around 7 g/l.
We have tried slowing ramp time and still receive the same results. I would appreciate any help.
Thank you,
Jake
plating shop employee - Grove, Oklahoma, USA
May 4, 2011
Hello,
I'm French and I try to treat parts as hard anodizing current pulse on a 2024 alloy
Can you give me informations on the ramps of anodized for this alloy ?
Cordially
Research and Development - Saint-Etienne, France
May 4, 20112024 and especially heat treated 2024 requires higher free acid, try 220 gm/L, then maybe 230 gm/L, let us know.
Always ramp 15 minutes up to a pre-determined 234 amps per square foot amperage then switch over to current control and let the voltage climb as the resistant thickness builds.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
Editor's note:
Mr. Probert is the
author of
August 29, 2011
HELLO
MY NAME IS ALI, I WORK ON HARD ANODIZING ON PARTS MADE OF 2024 ALUMINUM. I HAVE A PROBLEM WHEN CARRYING HARD ANODIZING IN END TIME IN HIGH VOLTAGE (45-50 V). CURRENT SUDDENLY GOES HIGH AND PART IS BURNING. PLEASE GUIDE ME
ANODIZER - ESFAHAN, IRAN
August 29, 2011
Hi, Ali.
In my experience this is usually caused by poor contact. Thus the item has little or no anodizing thickness, then the voltage goes high, breaking through whatever resistance was on the contact surfaces and exposing thinly anodized or non-anodized areas to 45-50 V which immediately causes burning.
Regards,
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