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Current hogging jigs

2002

Dear experts,

I tried to make jigs for my anodizing shops but had trouble as they became current hoggers. Following was the way they were made:
1 Main carrier was pvc coated aluminium bar to which ss wire with spring action was attached this too was pvc coated with just the tip being exposed.
2 Similar thing but ss wire was replaced by titanium thoroughly pvc coated with just the tip exposed.

Both the cases the current drawn was very high and the aluminium workpiece didn't get anodized. When the same workpieces were tried with aluminium wire they were anodized well, this being extremely labor consuming job apart from getting wire marks. Jigs is a very good option but these jigs did not work.

Could some one please throw some light on this and help me make the right kind of jig.

Thanks,

Viney Chaddha
- Gurgaon, India

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Two of the possible problems are poor contact, and wrong alloy for the aluminum bar. If the jig is made of an alloy than anodizes at a lower voltage than the alloy that the parts are made of you are condemned to trouble.

I think you may find the "Fundamentals of Plating Rack Design" of the Metal Finishing Guidebook helpful, if you have that book on hand, but there is a chapter on the subject of anodizing racks, and numerous notes scattered throughout The Surface Treatment and Finishing of Aluminum and Its Alloys, and it's a must-read.

Good luck.

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