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-----:Titanium Anodize - AMS 2487 and 2488 Solution Differences
Quickstart:
If titanium components are immersed in a conductive solution, and made the anode in an electrical circuit, the titanium on the surface is converted to titanium oxide. The coating can be a hard, functional, wear resistant coating per specifications AMS 2487 or 2488 Type II ... or it can be a thin highly-decorative coating in various colors. We have numerous discussion threads on each of these two general types of anodizing of titanium.
Readers are warned that although AMS 2487 & 2488 address the requirements and testing procedures, they do NOT provide sufficient info to guide a new user in implementing the process! And while this site prides itself on offering free technical help with finishing, this particular process is not yet generic but involves trade secrets and proprietary formulas.
You are welcome to undertake the process, don't make the mistake of thinking that you'll read how to do it anywhere. You will need to expend development efforts or retain a consultant to advise you.
Q. We want to anodize Ti-6Al-4V in alkaline solution as per AMS 2488 type 2 having pH 12. Kindly give details regarding voltage, current density, time and details of pre/post treatments required. Any help in regard will be appreciated.
S. Sreenivasan- Bangalore, India
2001
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A. Hi, Sreenivasan. Sadly, I'm afraid that this is one of those unusual cases where, despite the fact that there is an AMS spec for the process, the details of the process are known by only a handful of companies and held as trade secret. Sorry, but I don't think anyone is going to post a proven process for AMS 2488. Unless you retain a consultant who is experienced in it, I think that all you can do is start by obeying the requirements of the spec, and figure out the rest through trial and error. Best of luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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Multiple threads merged: please forgive chronology errors and repetition 🙂
Q. Does anyone have any experience with anodizing titanium i.a.w. AMS 2488? I would appreciate suggestions on things like current density, end voltage, process-time and a suitable electrolyte. The standard is not exactly informative on these aspects. Also, I don't understand how a coating (type 2) can be semi-conductive when processed to zero amperage?
Happy holidays.
Lars Jensenjobshop - Valby, Copenhagen, Denmark
2003
? Hello, Lars. If you could please tell us the parameters you're using and in what way the results are unsatisfactory I'd be more hopeful that it will receive comments from the readers. Thanks!
Ted Mooney, P.E.
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finishing.com - Pine Beach, New Jersey
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by Zhentao Yu
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Q. Well, so far we haven't tried anything really. But we have had a few inquiries so we want to start experimenting.
Lars Jensen [returning]- Valby, Copenhagen, Denmark
A. The below is to the best of my understanding --
The specification for AMS 2488 was written with the assistance of a company called Tiodize. They were the first to offer a commercial process in 1966. The specification is vague in solution and operating conditions. The testing requirements have been stringent. On the last revision (D) They dropped the need to test for compatibility with rocket fuel (Hydrazine). However they still call out for wear testing with dry film lubes. The test is not too conventional and there are a limited number of these old machines around, plus the test is expensive.
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However the dry film lubes have changed through the years, to eliminate solvents and graphite. So I do not know IF the spec can be met with current material. (Hope someone will tell me I'm wrong). Our application is for medical use so I don't give a hoot about the dry film lube. To the best of my information there are only five places in the US offering this coating, my shop being one of them.
Jon Quirt- Minneapolis, Minnesota
Q. I have a situation revolving around the galling of Ti. I understand from some research that the anodizing/oxidizing of Ti has some positive effects on wear. This seems to be an industry of well kept secrets and I have no knowledge of thickness or process effects on actual durability. It is very cute that many vibrant colors are obtained, but I am not concerned with this. I need a more functional wear layer.
Tom OathoudtSAM - El Cajon, California, USA
2004
A. There is no great secret to the protection of Titanium for anti-galling applications. Anodising of the Titanium may offer some assistance. Alkaline anodising produces a thicker coating than sulfuric acid anodising and both processes are freely available. For anti-galling I would probably look at the application of a dry film lubricant such as Molybdenum disulfide lubricants, again freely available on the open market. There has been a tendency over the last couple of years to go away from anodising Titanium as the benefits are seen to be minimal. A very simple process for the application of a dry film lubricant would be to vacu-blast the surface, ensure the surface is clear of the vacu-blast dust and then apply the lubricant.
Brian TerryWestland Helicopters Ltd - Yeovil, Somerset, UK
A. Dear Tom,
I am with titanium for 20 years. The practical way to improve its anti-galling or frictional properties is to oxidize it by thermal heating. There are some peculiarities here yet.
Andrey Igolkinprometey - St.Petersburg, Russia
A. Titanium nitride is pretty good at resisting galling, so you might look at either nitriding the surface or having a titanium nitride deposited on by physical vapor deposition (PVD). There are also several solid lubricant coatings that can be deposited by PVD, but I don't know if anyone is putting these on titanium.
Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover
San Diego, California
Multiple threads merged: please forgive chronology errors and repetition 🙂
Q. Is there a more precise way to define the requirements for titanium anodizing that could be used instead of AMS 2488? That spec is not really sufficient for control of the results of an anodizing process. Is there another standard spec or additional requirements that can be placed on a vendor to assure reliable and repeatable AMS 2488 treatment. For example, could hardness or other post-process tests be required on each lot? I am working as a consultant with a company that has received anodized titanium samples from two different coating vendors, both of whom supposedly met the AMS 2488 spec, but the wear resistance of the films from the two vendors is very different.
Francis E. KennedyProfessor, engineering school - Hanover, New Hampshire, USA
2006
A. The AMS 2488 is purely for the aerospace wear test of a combined Titanium anodic coat and dry-film lubricant. You are absolutely correct that it has no sufficient control of the results of an anodizing process, especially for the medical implants.
Kas Amadi- Dayton, Ohio
A. Hi Francis.
Seconding Kas' comment, this has been a long-standing problem. Many shops purchase the AMS 2487 and 2488 standards, assuming the standards will tell them how to produce this coating, but they don't. The shops may or may not comply with the standards, but those standards don't actually tell them how to best do Type II alkaline anodizing of titanium because that is still trade secret information. For example, they mention the pH of the electrolyte but not what it is; they don't discuss amperage or voltage beyond that it should be slowly raised until current flow stops :-(
This is not to say that the standards aren't valuable, just that they don't tell you how to do the process.
I don't actually know the history, but Tiodize and/or Titanium Finishing Co. and/or perhaps another company developed these processes and everyone keeps their knowledge of them proprietary. Some other shops may know how to do it well at this point, and some consultants do as well, but the gist of it is that it ends up being a proprietary process not a generic one, and the issuance of AMS 2487 & 2488 hasn't changed that :-)
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
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Wear Resistance Test per AMS 2488 on Titanium Type 1 and 2 Anodizing
Can your facility perform a Wear Resistance Test per AMS 2488?
Test Specimen Defined:
6AI-4V Annealed Titanium Ring IAW AMS 4928
Ring will be Titanium anodized as (Type 2) per AMS 2488D.
Ring will also be coated with dry lube to a film thickness 0.0003 to 0.0005. per MIL-L-46010/MIL-PRF-46010
[from DLA]
Type I
Actual Test Defined (AMS 2488D):
4.5.1 Wear Resistance:
4.5.1 Equipment: A block-on ring test machine calibrated and operated in accordance with ASTM D2714
4.5.1.2 Procedure: Mount an anodized and dry-film lubricated AMS4928 (titanium 6AL-4V) test ring on the block-on-ring test machine according to manufactures instructions. Place sufficient weight on the bale rod to achieve 630 pounds normal force (2802 N) when load is applied. Start the machine. After one minute, gently apply load lever to the system. Terminate the test when coefficient of friction equals 0.20. Repeat the room temperature test twice using anodized and lubricated test blocks and rings in each test. The average of test results shall not be less than 75,000 cycles.
Anna Berkovich
(ed. update July, 2025: sorry, Anna has retired)
Q. The seeming differences between AMS 2487 and AMS 2488 titanium anodize specifications appear to be in the solution pH and the test requirements. 2487 requires solution pH maximum of 12.4 and has a lot more testing requirements (galvanic corrosion, foil, voltage breakdown, electrical resistance, taber) than does the 2488, which specifies a pH minimum of 13.0 and for non-propellant exposure parts, only Taber testing.
Can anyone tell me what the reason is for the solution pH specification differences between the 2487 and 2488 specs? I have anodized titanium parts using the higher pH 2488 solution (in my tank, about 13.3), and then subjected the anodized test panels to all of the 2487 testing, and they have passed all of the tests with no problems.
Is there an issue with exposing some titanium alloys to too high a pH - perhaps causing metallurgical degradation or something else? Does the pH difference have any engineering effect on the quality of the part/anodize coating?
- Los Angeles, California, USA
November 18, 2011
A. Hi Mike
I am not familiar with the specs you quote but in my opinion any pH measurement over about 11 is meaningless. Even at 9-11 special electrodes are essential.
High pH solutions should be controlled by titration.
Geoff Smith
Hampshire, England
RFQ: We have a requirement to set up Titanium Anodising Process per AMS 2487 / AMS 2488 Type II. We are looking for consultation service to support us in setup up the process and test facility.
Any leads will be highly appreciated.
Thank you.
- Bangalore, India
February 19, 2022
Ed. note: This RFQ is outdated, but technical replies are welcome, and readers are encouraged to post their own RFQs. But no public commercial suggestions please ( huh? why?).
Q. We are an aerospace metal finisher who anodizes titanium per the AMS 2487 specification. That spec requires, among a lot of others, a periodic test for 'galvanic corrosion'. The method specified is to tightly fasten a titanium anodized 1" x 6" flat plate to a similarly sized, bare, 1100 alloy aluminum plate using nylon bolts through (2) holes in the opposite ends. You expose that assembly to ASTM B117 salt spray for one week and then 'check for evidence of galvanic corrosion'.
I can find no spec governing that test and nothing that might give a hint of what a pass or fail would look like. Obviously, the bare aluminum is going to corrode -- especially at the junction of the two plates, because unlike in a standard salt spray test where a single, almost vertically inclined panel is exposed to salt fog such that any salt moisture ultimately beads off of the surface of the panel), the fastened-panel salt solution would just 'sit' between the panels, causing way more corrosion than would be experienced on a single panel whose salt solution mostly beads and drops off.
We have very spotty success with multiple labs in passing the test, in my opinion because they don't accurately interpret 'evidence of galvanic corrosion'.
Any experience or guidance would be helpful. I really can't see how the AMS organization can specify a test with such loose pass/fail criteria as that!
- Gardena, California
February 14, 2022
A. Hi Mike. Just a guess, but maybe you're supposed to tape or mask the edges because the corrosion you are looking for is not between the two panels but on the outside of the panels?
I agree with you that when a spec calls for some kind of testing it needs to be explicit rather than vague about what constitutes passing or failing that test :-)
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
! Regarding the anti-galling issue, we have done titanium anodize for years, but it has been using a highly alkaline recipe that was created by the chemist who worked here forever and died on the job in his 80s - a few decades ago.
There are spec requirements for putting SFL/DFL on titanium anodize - mostly for threaded applications. Both the traditional titanium anodize specs, AMS 2487 and AMS 2488, have a periodic test that tests the ability of the titanium anodize coating to bond well with the post-anodized DFL/SFL coating. It is loosely referred to as the "block on ring" test, and it uses special test "blocks" and "rings", produced only by Falex, which have been titanium anodized and then coated with the DFL/SFL. The ring is put through several thousand cycles of wear against the block, and if the DFL/SFL or anodize coating wears off before the required number of cycles, the test is a fail. I have been told that the vast majority of test attempts fail.
All that said, there is very little I have found that might help people pass that test -- which costs upwards of several thousand dollars depending on how many cycles the test goes. I can find no information on what DFL/SFL might be best suited to pass, and I have talked to the big DFL/SFL makers as well as other titanium processors. I can find no information on whether the titanium test blocks/rings should be "grit blasted" before the anodize, as that grit blast is a usual pre-treat for the application of all DFL/SFLs, etc.
I was told a month ago by Everlube's expert that they stopped doing the test because it was so hit or miss with the results. I made an inquiry to the AMS people for test clarification - because besides requiring the test, the 2487 and 2488 specs don't clear anything up - and I was simply told to raise the issue at the next committee meeting.
If anyone wants to exchange any info/experience on this - it would be greatly appreciated. Thanks!
VP, Operations and Engineering - Gardena, CA
June 22, 2022
Falex test equipment on eBay (affil link)
A. Mike,
We ran such tests with Falex back in 2013. Their results (71K) were very close to required 75k. I can forward the official Falex report upon request. The Falex rep told us that it is very unusual. Other companies cannot come so close to the required results. He encouraged us to improve the processing and submit the samples again for testing. However this testing is very expensive. I usually suggest that companies who bought this technology from us and desire to obtain 2488 certification to do testing on their own.
adv.
Concerning grit blasting - our technology does not create "fur" on the surface, but grows thick enough micropore surface to hold lubricant inside the pores. As to others' methods with "fur" growing on the anodized surface - I suspect it will be smeared away after the first ring-cube cycles.
Anna Berkovich
(ed. update July, 2025: sorry, Anna has retired)
Q. Question to the titanium community about AMS 2488 test.
Does the 2488D or 2488E test require lubricant be applied on anodized surface prior to submitting parts to the testing facility?
Anna Berkovich
(ed. update July, 2025: sorry, Anna has retired)
March 2, 2023
A. Assuming you're referring to the wear resistance testing, section 4.5.1.2 of AMS 2488E requires application of dry film to the test specimens before testing. Allowed DFL specifications and thickness are given in section 3.5.2.
Jordan Buck- Syracuse New York
October 16, 2024
Q. Hi
I understand titanium anodizing will reduce the wear & galling.
Can I know if the galling still exists when both contact parts are titanium anodized?
- USA
October 17, 2024
This is a meeting place for camaraderie & sharing, not a free consultancy. So some readers don't engage with anonymous posters.
A. Tiffany,
As a variation of AMS 2488 or 2487, where anti-galling surface is for multiple operations, it is possible to achieve a pretty inexpensive thin anodizing layer that possesses anti-galling properties for a limited times of screwing-unscrewing, for example for medical implants.
Anna Berkovich
(ed. update July, 2025: sorry, Anna has retired)
Readers may also be interested in these related threads:
• Topic 61400 "Galvanic Corrosion Test for Titanium Anodize AMS 2487"
• Topic 33504 "Anodizing Titanium for Wear Resistance & Anti-Galling"
• Topic 3649 "AMS2488 & AMS2487 Type II Anodizing of Titanium Q&A"
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