Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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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 Aleksiewiczcustomer / plating houses - Seymour, Connecticut, USA
August 27, 2008
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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. Aerospace - Yeovil, Somerset, UK September 1, 2008
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