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Specifications for hardcoat anodized extruded aluminum "surface blemish" limits

We purchase hardcoat anodized 6005A-T5 aluminum extrusions for use in conveyors. The top surface of the extrusions carry cardboard cartons and are visible. Do industry standards exist for specifying limits for blemishes and scratches? Our suppliers are reluctant to sign-up for limitations on the cosmetic finish of these extrusions, especially since their anodizers pack and ship the finished parts direct to us.

Martin Heit
Design Engineer - Cincinnati, Ohio, USA
August 21, 2008

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Hi, Martin. No, there are only sample boards of parts that have been agreed to be acceptable and unacceptable. But I don't think there should be blemishes on an "A" surface (a limited area where it is agreed that aesthetics are especially important) if the aluminum is good.

There is nothing inherently wrong with drop shipping from the anodizer, but there is something very wrong with the implementation if it is used by your supplier as an excuse for exercising no quality control :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 22, 2008