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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Looking for an industry workmanship standard for Yellow Chromate
Q. I supervise Incoming Inspection at our company. We buy numerous sheet metal parts which are often times required to have a yellow (zinc) chromate finish. I am trying to develop some workmanship standards by which to visually inspect parts. I have asked several of our platers what workmanship or industry (or ASTM) standard they are conforming to and they say that they don't have one. Are there published industry standards/guidelines/inspection criteria that I can adopt?
Scott TschetterElectronics Quality Engineer - Lynchburg, Virginia
2004
A. Visual standards are always tough, but the more so when you seek visual standards for a finish which is not usually considered a decorative one like zinc plating with yellow chromate.
Some folks have a gut objection to home-made sample boards with acceptable/unacceptable parts mounted on them, and I appreciate that queasiness; but sometimes they're the only way. It's just not possible to objectively say how pronounced a drip stain must be before it's aesthetically unacceptable, or how light is too light or how dark is two dark. The only thing you can do is agree with your vendor on acceptable & unacceptable sample parts.
But don't let the visual standards dissuade you from the more objective tests. There are industry standard tests for salt spray resistance, adhesion, thickness testing, etc., etc., and these should be enforced before you look at parts for aesthetic acceptability. We should probably use the term 'aesthetic standards' rather than 'visual inspection standards' since we are not visually checking acceptability but judging aesthetic acceptability :-)
Standing by, waiting to be corrected . . .
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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