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Type II hard anodizing

(-----) 2006

We have carried out Type III hard anodizing on 6061 T6 & 7075 T6 sheets. The coating has failed in Taber Abrasion test as per Mil-A-8625 [link is to free spec spec at Defense Logistics Agency, dla.mil].

Request suggestions to improve the Abrasion resistance of the coating.

Biren Desai
Manufacturing - Mumbai, India

First of two simultaneous responses -- 2006

Hello Biren,
You fail to mention the Current density you are processing your parts or the temperature of your bath, both critical to producing a Hard Anodize.

Bill Grayson
metal finishing - San Jose, California, USA

Second of two simultaneous responses -- 2006

The header says type II and the letter says type III. If you did a true type 3, at 0 deg C or lower and used a high enough amperage/voltage for long enough to get a proper thickness, it will rarely fail. So, what did you not do correctly. Forget what the floor said, go and watch a run and then check.
I forgot, adequate agitation to maintain a uniform temp of the solution.

James Watts
- Navarre, Florida

First of two simultaneous responses -- 2006

There are so many factors that affect a hard anodise coating that, with the detail you have provided, nobody here could reasonably give you an answer.

Please let us know what your operating conditions are, e.g. pretreatments, solution concentrations and whether you are using any additives, what temperature you are running at and whether you are using a chiller or dry ice and what voltage cycles you are using.

After that you still need to consider the alloy, so please let us know what alloys you are processing.

Given all of this someone may be able to give you pointers as to what your problem is, otherwise your request will remain unanswered.

Brian Terry
Aerospace - Yeovil, Somerset, UK

Second of two simultaneous responses -- 2006

Most common cause is inadequate cooling. Increase agitation of the anodizing solution and/or lower its temperature.

Ken Vlach [dec]
- Goleta, California

contributor of the year Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.


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