aluminum anodizing question

[larry9901]

Hello everyone,

This is my first post and I am looking forward to being informed.

A little about myself, I own a Injection Mold Tool and Die Texturing company, we acid etch the finished appearance in the mold itself.

Anyways, while I was making a sales call at one of my customers I noticed we was drilling out holes in these small 2"x4" aluminum parts. There were thousands upon thousands of them. After doing his part with the bits he has to send them out to be "annodized"

He then suggested that if I were able to do the annodizing I could probably have that business.

I want this business so my question is:
1) How do I determine what type of annodizing are on these parts?
2) Excuse my ignorance, but are there several types of aluminum annodizing?
3)If I were to obtain a part, could it be easily identified as to what is on there?
4) Once its determined, how do I get started starting a small line?
5)over all, is this a high risk complicated process?
6) If there is anything else I should be asking please advise.

Thankyou for your time
I am looking forward to this adventure.

Larry

[BobFrapples]

1) Theres two main types of anodizing. Type II (1mm max thickness) and Type III (hardcoat, 2-6mm thickness), the only way I can tell is because I do Type II, and I can personally feel the difference of the hardcoat. Maybe someone else knows?

2) There are 2 main types issued above, but yes there are others.

3) Not sure what you mean by "what was on there", do you mean the type of anodizing on it?

4) You'll need a few items to get started, theres a list in other topics if you do a little research. You said theres "thousands" of these 2 x 4 plates. If your trying to anodize these all at once, it would take A LOT of power (as each of these are 16 sq in). Not sure if a small setup would be appropriate to do all of these, at once, or in sections, as it would take a long time to do them all in sections without upgrading to a large line.

5) Its not a high risk process, its fairly easy actually once you get the hang of it (usually about a week or two depending how often you do it). Main issues, people like to skip steps and find shortcuts. Yes there are shortcuts, but you have to know how it works in order to use them.

6) You might want to talk to someone else with a larger line. Thousands of 16sq in parts is quite a bit (to me atleast, I usually do 200 sq in per run). So maybe someone else here can clear up any questions.

[sswee]

I want this business so my question is:
1) How do I determine what type of annodizing are on these parts?
Customer should be able to tell you if there is a manufacturing call out for anodizing spec. If there is no call out, then color can indicate type. Type II is normally used for dying colors. Type III hardcoat is normally limited to black, gray or a couple of other dark colors due to small pore size. Other than that, only lab testing can determine true type.
2) Excuse my ignorance, but are there several types of aluminum annodizing?
To my knowledge.Type I, II, and III. There are different methods most using proprietary chemical mixtures and methods.
3)If I were to obtain a part, could it be easily identified as to what is on there?
Basically no. Refer to #1.
4) Once its determined, how do I get started starting a small line?
Get and read a Caswell anodizing manual
5)over all, is this a high risk complicated process?
No more so than most other jobs. Common sense needed above all else.
6) If there is anything else I should be asking please advise.
Since you are looking at it from a commercial venture, you may need to investigate your local laws and regulations if any on this type of work. You may be all set since you are already doing acid etching but I can't say.

[acidrain]

Plan on spending ~$1000 to get started on a real venture. If you get into a temperature controlled ano tank, plan on spending another $500-$1000.

[larry9901]

Thanks for the information.

I found out what type of anodizing is on theses parts.

Mil-A-8625 Type III is the spec.

Does anoyone know what this means? Please advise as to what I need to process this coating.

Thanks again,
Larry

[pyroracing85]

Plan on spending ~$1000 to get started on a real venture. If you get into a temperature controlled ano tank, plan on spending another $500-$1000.

that is it?

I bought my tanks alone and they were $1500 (24x12x24) I haven't even bought the chemicals nor a chiller or rectifier.. Not even raking yet.

If you want a decent set up plan on spending $7-10000 is more like it.

[dmiom]

Thanks for the information.

I found out what type of anodizing is on theses parts.

Mil-A-8625 Type III is the spec.

Does anoyone know what this means? Please advise as to what I need to process this coating.

Thanks again,
Larry

Hi Larry,

If its Type III then its (relatively) a different game to what most, if not all, folk on here do.

The method practised by most of those here is the Caswell LCD ("Low Current Density") method, or derivatives thereof, which generates a type II coating. The Caswell LCD is a great base to work from and develop type II, but is not type III.

Type II is a relatively open matrix which is able to accept dye; and if properly prepared & processed is relatively hard wearing - however type III is even harder wearing.

The Caswell LCD process is relatively easy for home / prototype / small production use; and is capable (provided the preparation, chemistry, racking, rinsing, timing, temperature etc. are all correct) of producing consistent, high-quality results which can take an attractive ranges of dyes. We started with a basic Caswell kit line which we have enlarged over the years which we use to anodise one-offs and small runs for our products for the professional broadcast, film & motorsport industries, and for third-parties - and its perfect for us. However, its not type III.

The essential difference is that, using the Caswell LCD method for type II it is done in a relatively dilute acid at 68-70F using low current densities which start in the range 4.5 - 6 ASF (amps per square foot) - the ano tank may require a chiller plant but of relatively modest proportions to dissipate the input electrical power from the anodising.

Type III can use slightly different chemistries - but key factor is the lower temperature and the current density. The lower temperature (e.g. 37-40 F) gives a smaller matrix - i.e. more of the honeycomb cells per square inch which gives a more robust coat (although the smaller cells mean that it doesn't take much, if any dye; and any perceived colouration is really only the matrix blocking the light and results in shades of grey). Because of the lower temperature, if run at the LCD current densities, the layer grows so slowly that the competing dissolution from the acid electrolyte can mean that you might never build up any useful thickness - so it may need to be run at 20 ASF or more, instead of say 6 ASF for LCD method. Pumping this much electrical energy into the tank really does put the emphasis on the electrolyte being circulated through more of a refrigeration plant than just a chiller. You will also need really vigorous electrolyte circulation (using for example Little Giant magnetically-coupled HC pump). Circulation is needed (a) because the anodising process can give rise to warmer layer immediately adjacent to the growing surface - which can lead to bigger matrix and accelerated dissolution, and (b) as others on here have pointed out, it can lead to the formation of micro-bubbles which can act as an inhibitor/insulator and lead to defective spots with thinner matrix.

I would suggest that, if you can do so easily, you could check if they really need to have Type III - or is that just what they're getting at the moment? or is it just what they think they're getting!

Type II can be pretty darn good , and is a lot more achievable; and (if appropriate) can open the way to a greater variety of finishes (and, as SSWEE has alluded to above - they may say type III but if you find they have a variety of colours it may not be type III at all ! )

If it has to be type III, you may get some general help here; but you may also find it useful to search on finishing.com

Dave