glen2002

No solution here, but thank the two of you for behaving like gentleman in this dispute. A very refreshing change from the name calling and slander on the board we normally see in a dispute. You both create an excellent example. I hope it is resolved fairly for both of you.

2+2

Yes, goood to read civilized behviour. FWIW, I think Tom MGinn's and Travis' solution is the most fair. Dont know how much such independent analysis costs but if its not that much, mumzer may consider picking up the tab in the name of client service...just a suggestion.

Travis - sflraver

It does not cost anything. Just send the arm back to mumzer. He takes it around town to a few anodizing places and says "what happened to this." Maybe throw in something like "I am looking for a new place to get a BUNCH of these anodized." throwing out a line like that will get you more in-depth answers, for free.
Now the 3rd party company(s) you talk to are going to be straight forward when you tell them what happened. If the material is a pain to work with they may say.. "oh ya, that happens all the time with that stuff. We don't want to take the liability of working with it". Or may say... "I have seen that before. The aluminum was made with impuritys and it just $%^%ks everything up when you drop it in the etch. Look at this piece that it happened to we did a while back... etc..."
If you are nice and bring the prospect of new business, which I assume is a possibility if you are going to be making more of these, people will talk you ear off. May even take you to lunch.

NOW GO FIND OUT WHAT WENT WRONG .... geeze

fast951

Travis, it's a good idea to get opinions from different shops. Wouldn't it be best to be honest to the people that will take the time and stop their work to answer your questions?

slim_boy_fat

Absolutly

PrerYDoG

So true, but in this instance, if mumzer is doing it, you can approach it like so:
You say you fab these arms, and some customers get them ano'd. There's been a problem with one person doing it, you'd like to be able to offer them ano'd in the future for those people who want it that way, but you want to know that the current situation will not repeat itself, and you'd like to know why/how that would happen.

Now, that is being completely upfront and honest, and gives a shop a chance to answer questions and gain business at the same time. It's a win/win situation.

Skip Wolfe

The problem with this is that it is really only opinions and conjecture on the part of the platers. For example, for thos of you who don't know I work in the municipal water treatment industry. I'm an ME by degree, but have been forced to learn a lot of water chemistry and have been doing this for quite a while, and have been around around both in the field on the practicle side of things, and in the lab on the theoretical side of things. Just last week, our secretaries husband who is a plumber and a handy man, brought in a sample of black water from some rich dudes house and wanted my opinion on what it was. I was willing to swear I knew exactly what is was and would have put money on it, but I asked him to get some more samples and I would have run them through our lab just in case. I was dead wrong. It was a very unusual bacteria that was obvious under a microscope, but to the naked eye looked like something else completely. So I did gave the "oh yea, I see it all the time" answer and had to eat my words, but that's how it goes sometimes. Ask different people there opinion on what happened by just visually looking at something and you'll get lots of opinions but no real facts.

This is what I am struggling with.

krutschman1

Ok, Ok, everybody is missing the easy test. Take the bad arm, cut a section of the arm off and remachine it until it's a pit free, machined surface (all surfaces). Take the test chunk to a different plater, letting them know it's 2024, of course, and see what they come up with. If it pits again, then it's time to talk to the metal supplier. Trust me, if there's a problem with the billet, they will want to know about it. There are too many liabilities with aircraft aluminum to take chances. I am a modification aircraft mechanic on large jet transports. I work with 2024 and 7075 daily. If we suspect a problem, it goes all the way to the source until the problem is resolved. The FAA mandates it. Nobody would want to fly on a plane made from the same batch of aluminum alloy as your arms if there is a problem with the alloy. Even if they were machined from the same billet, there have been problems in the past where a portion of the billet tested good, but some sections in the billet had weaknesses from improper processes or impurities in manufacturing. This is highly unlikely, but possible. Once this possibility has been eliminated, then it's time to start shifting back towards the original chemical plater. I'm not saying who's right or who's wrong, because both of you are really at a loss. It's a shame these things happen, but unfortunately, they do.

mumzer

goddamn im dopey...this is so simple im feeling slightly retarded for not thinking of this....

thanks....

skip? thoughts?

slim_boy_fat

Just one thing, you might want to get someone independant to chop the test sections out do th emachine work and get the anodising done. I would get one done telling the anodiser its 2024 and another not telling for a comparison. Might be a pain but would really be no comback from anyone.

Travis - sflraver

If it happened in the etch then that is simpler yet. It happened in a 30 sec. time frame so just chop off a piece and drop it int a lye solution for 30 seconds.

I am still so very interested in what went wrong with the piece. The only explanation I can find in my books is during the actual anodizing process and not in the etch.

Skip Wolfe

Mumzer - you have mail.

krutschman1 - the only problem with this is that it eliminates any surface variables that could have been caused by improper machining. It would be a good data point, but not the magic bullet.

Travis - I definitely did not happen in the anodize bath. The plater ran it through, did not get a good coat, which can happen with 2024, and then ran it through etch/desmutt. I believe it actually happened in the desmutt bath.

Travis - sflraver

So he anodized it first, then etched the anodizing off and put it through desmut to anodize it again. The reaction happened in the desmut bath the second time around?

Bill

Well I must add my two cents.

I also purchased a set of control arms from Mumser. When I picked them up Mumser also recommended that I have them hard anodized.

I took them to a plater that is aerospace certified and 9002 (not sure of the exact numbers). His first question was "what blend aluminum is this". He said without knowing he could ruin the arms. He told me he would not hard anodize them without knowing. I called Mumser and got the mix. When I told the plater the mix, he said nothing further.

We also discussed etching. My concern was the ball joint machined area. Mumser told me it was a friction fit, that required heating to 200 degrees prior to the ball joint installation. I asked the plater what thickness the hard anodizing process would add. He said that the entire process was 50 thousands, but would only add 25 thousands to the overall thickness. The other 25 thousands turns the base aluminum into the hard anodizing. So I had the plater etch 25 thousands off of the arms, so the final plated arm would be the same dimension as before the hard anodizing process. Two days later I picked up the arms and paid $80.00.

As all who attended our last Pizza Run at my house can attest, My Mumser control arms are BEAUTIFUL. I proudly showed them off to anyone that was interested and even those that were not interested. (read: my wife)

I am not a moralist and so I will refrain any comment to that end. Just thought I would state my experience. So far, I am very pleased with my arms. I have yet to mount the arms and put them into service.

I have pictures, but my camera is at home. I will post the pictures later.

Tom M'Guinn

I can attest to that. Best looking control arms I've ever seen.