How to test the quality of black anodized aluminum

[Daidawei]

We are receiving black anodized aluminum cases for our products that are easily scratched and the layer is probably too thin. What tests can we do to check the quality, what tools would we need and how would we perform them? Is there a simple way, like a scratch test?

Thanks for your help!

 

[jasonb067]

Re: How to test the quality of black anodized aluminum?

Is the anodize cosmetic only or is there a functional purpose? I imagine the specific requirements are either on the drawing or referenced in a specification or standard. Those will usually describe test methods which may be as simple as a thickness requirement which will require a laminia thickness gage.

Also anodize should generally not scratch off as it is not a coating but is rather a deposit or growth of aluminum oxidation.

 

[Daidawei]

Re: How to test the quality of black anodized aluminum?

The anodizing is for cosmetic appearance. I will have to check the drawings for the requirements. I checked our cases and the indeed there are scratch marks where you can see the base metal. Perhaps the supplier didn't do it right or didn't anodize it at all and just painted it black. Either way, our IQC missed it (I work in China).

Thanks.

 

[John Broomfield]

Re: How to test the quality of black anodized aluminum?

We are receiving black anodized aluminum cases for our products that are easily scratched and the layer is probably too thin. What tests can we do to check the quality, what tools would we need and how would we perform them? Is there a simple way, like a scratch test?

Thanks for your help!

Daidawei,

Anodizing is a 7.5.2 process. Your supplier selection criteria should have ascertained the status of their anodizing process against your specification for black anodized aluminum cases before placing the order.

Now you may be stuck with what you have bought.

Here is more guidance on specifying and testing anodizing:

http://www.anodizing.org/Reference/reference_guide.html

Best wishes,

John

 

[jasonb067]

Re: How to test the quality of black anodized aluminum?

If the material is being scratched where are the scratches coming from? If the material is simply not as durable as it should be you may have a problem that will be a long time correcting. Otherwise eliminate the scratch source.

 

[Daidawei]

Re: How to test the quality of black anodized aluminum?

Yes, we are definitely stuck with these. I just don't want it to happen in the future. I just started this job this week as a project manager but have somehow become the QA manager (surprise!) and I'm not too familiar with anodized materials.

Thanks for everyone's help. I think I can take it from here.

 

[silentrunning]

Re: How to test the quality of black anodized aluminum?

One quick and simple test to see if it is actually anodized as opposed to a dye or chromate is to check it with a continuity tester. Put a probe on each end of the part. A properly anodized part will have no continuity. A chromated or dyed part will show good conductivity.

 

[Murphys Law]

Re: How to test the quality of black anodized aluminum?

Daidawei - Are you buying these off the shelf or are they making them only for you?

What does you contract say about layer thickness and the quality level of thickness/scratches etc? There maybe a minimum level of defects within this shipment that is 'allowed' per contract.

Did you even specify an Acceptable Quality Level ? If you didn't, then you're company has a problem in your contract process and the contract then is whatever the supplier says it is per their Average Outgoing quality level.

ML.

 

[Big Jim]

As Murphy's Law alluded to, a key here is what requirements did you flow down to your supplier?

If you simply stated black anodized, that is probably just what you got. If you stated black anodizing per one of the specs so nicely provided by John Broomfield, particularly hard anodizing, you may not have received what you asked for.

Two principles here in dealing with suppliers:

You should get what you ask for.

You will get what you permit.

Tell them what you want and then hold them to it.

If you didn't ask for the right thing, you may also have an engineering problem in that your engineers were not specific enough with the requirements.

 

[kgott]

We are receiving black anodized aluminum cases for our products that are easily scratched and the layer is probably too thin. What tests can we do to check the quality, what tools would we need and how would we perform them? Is there a simple way, like a scratch test?

Thanks for your help!

Some time ago I worked for a company that made transportable acommodation and we used anodised aluminium windows and we had smilar issues. One of the things we did was use a sample window frame against which purchased windows were tested if there were doubts about the quality of it.

The sample was viewed under cover at a set height off the ground and viewed from two different angles. It was then taken out outdoors and placed directly facing the sun at the same height and looked at from the same two angles.

Doubtfull product was placed along side the sample on both occasions. The supplier was invited to participate or witness the test which they did in the begining. Thereafter they simply accepted the returns and used the same test for their own testing

Perhaps you could try something similar