Summary for partial type iii anodization Discussion
Partial type III anodization for small aluminum parts is discussed as a cost and process challenge for a key-ring-sized consumer product. Chris Jurey suggests hardcoating the parts as an assembly, while Tom Gallant also asks whether the parts can be assembled before anodizing, noting that this would likely be cheaper than masking or machining. Joseph R. Goodman offers a practical shop-floor method: leave about .010" extra material on surfaces that must remain conductive, hardcoat the entire part, then machine the conductive surfaces back to final size so the tool can cut under the coating. Terry Ciszewski agrees that anodizing the three parts assembled would be the most cost-effective approach, but adds that if that fails, combination racks that both rack and mask parts may be worth trying.
In the past year, my corporation has brought our one consumer product from concept to finished prototype. It is a product small enough to fit on a key ring. We have in place packaging, electronic components, assembly, warehousing, etc…
The one piece we are missing is a suitable manufacturer for the body of the hand-held device. We are looking for some assistance with finding and selecting said manufacturer within a short period of time. The body is 6061 – T6 aluminum. Although it is designed in 3 pieces, we need electrical current to flow through them as if they were 1 piece. Easy enough to do with tight fits…
But we want the outside of the body to be hard-anodized.
The problem is that we are having problems finding companies that can deal with masking small pieces in a cost-effective way. The anodizer typically wants the machiners to machine off the hard-anodized coating after it is put on, because masking thousands of small parts is so labor-intensive. The machine shops don’t want to work with HA because it is so hard.
I am hoping some folks here have had experience with this and can suggest cost-effective solutions.
JB Snyder
– Avon, Connecticut, USA
2004
 | A. Have you tried hardcoating it as an assembly? Chris Jurey, Past-President IHAA A. Can the parts be assembled for the anodizing? Seems like that would be a lot cheaper than masking or machining. Tom Gallant |
A. JB,
We are a machine shop that has anodizing capability and we use the process that you describe quite often. Leave extra material (say .010″) on those surface that will will need to be conductive, then have the entire part hard coated. Then have the conductive surfaces to final size. The extra material allow the cutting tool to get “under” the hard coat and allow it to be machined away relatively easily.
Joseph R. Goodman
– Greensboro, North Carolina
2004
A. I would agree with trying to anodize the three parts assembled this would be the most cost effective method.
However if that does not work for you I have seen racks that can mask the part at the same time as racking them. Have you tried a combination rack that also masks parts?
Terry Ciszewski
– Northbrook, Illinois USA
2004
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