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Technical Specification for Aluminum surface Finish Prior to Coating

2004

We build GPS/DGPS communications products which are supplied to the industrial industry. We utilize aluminum extrusions, with aluminum endplates. I suspect the endplates are stamped out, then drilled/machined to meet form/fit/function.

We have problems with the surface finish being, well, inconsistent. It is as if the outermost sheet of aluminum may have been used which was dragged across the floor. The result is powdercoat application (silver in this case with a sorta gloss finish) magnifies any/all scratches, dents, etc.

Is there common terminology, or a recognized standard to which we can specifiy on the FAB drawing which will clarify this with our contract manufacturer (overseas)? Thanks in advance.

Simon Van Leeuwen
CSI Wireless - Calgary, Alberta, Canada

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It is typical to communicate to the supplier that different surfaces fall under certain class's, like A,B,C, or 1,2,3. Send them a definition of what the quality expectations are for each class and then you can add the class to the drawings, as an example, the drawing might indicate "front side of part is class "A" (no blemishes allowed), rear side is class "C" (some blemishes allowed). Another way would be to produce a sample of what you expect the surface of the parts to look like and send it to them with a note that says "if the part doesn't look like this, don't send it to me". You're in the drivers seat when it comes to defining the quality you get from your suppliers, expect him to increase his prices if you tighten up the quality.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2005