No passwords, No popups, No cost, No AI:
we earn from 'affiliate link' purchases, making the site possible

Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

finishing.com -- The Home Page of the Finishing Industry

  The authoritative public forum
  for Metal Finishing since 1989

-----

MIL-A-8625 Type II adhesion test

We currently produce many parts that require finishing to MIL-A-8625 / MIL-PRF-8625 [on DLA] type II. Some are dyed some are not. We are being rejected for failing the adhesion test. Our customer is performing the adhesion test after heating the part to 250 deg. My question is if this is the proper way to test.

Robert Aleksiewicz
customer / plating houses - Seymour, Connecticut, USA
August 27, 2008

I cannot tell you if it is proper or not but: The thermal expansion of the oxide is 1/5 that of the underlying aluminum, cracking will start to occur at 80 °C and up. My source is Sheasby and Pinner's latest books, they do not mention adhesion, but surely with that difference in thermal expansion of 5 times, then something has got to give.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

August 29, 2008

Did your customer tell you that you needed to meet this requirement? If not and you are certifying to MIL-A-8625 Type II then I cannot see how they can reject them. If you agreed to this in the original contract then you have no option other than to comply.

Added to this I wouldn't ever consider a thermal test for adhesion due to the differences in thermal expansion rates of aluminum and aluminum oxide, the oxide having a much lower coefficient of linear expansion than the aluminum.

Brian Terry
Aerospace - Yeovil, Somerset, UK
September 1, 2008

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: