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Anodizing Al precision miniature screws for electronic device
November 15, 2012
I am doing technology development job in company supplying precision fasteners/parts to electronic industry, e.g. cell phones and tablets.
There was inquiry from customer that they wanted some screws/inserts that are very light. We tried out both Al and Ti. Because Ti has much higher strength and hardness so customer finally opted for Ti.However, machining Ti has a very high cost.
I am thinking if the Al screws/inserts are subjected to anodizing followed by sealing, it might be able to replace Ti in such kind of application.
1. is it possible to do anodizing in batch process, without racking of the screws?
2. is the anodized layer very brittle? after assembly the screw, will the anodized layer remain intact?
I am very new in this area, please kindly give your comment. Thanks
fastening surface technology - Singapore
A. You might want to try 'basket' or 'barrel' anodizing. I assume that the part being mostly threaded, and with larger head than the stem, will result to minimum contact marks. There is no guarantee for 100% success. You will have to check each part using conductivity test. Why not use Al high strength alloy and temper, coated with Alodine or Iridite instead?Dado Macapagal
- Ont., Canada
A. The anodic film formed on a sharp edge, like a thread, becomes 100% aluminum oxide, is very brittle, and breaks off.
Robert H Probert Technical Services
Garner, North Carolina
Thanks for your replies.
If the anodized layer is very brittle, it is then not able to withstand the impact during automatic assembly.