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Do I need multiple rectifiers for anodizing?  

June 13, 2008

Hi Experts,

This is Rizwan Shaikh from Mumbai, I was thinking of setting up a new Anodizing unit in Mumbai, just had few questions on this. I would be starting my Aluminium Caps manufacturing in a shortwhile and I would require a complete anodizing plant for that same. So my questions to you all is:

1. How many Rectifiers I would need to anodize a cap size of Dia. 30 mm x 50 mm. And what should be the capacity?

2. Is it possible to use only one Rectifier with high voltage capacity instead of two?

3. If used only one Rectfier then what will be Output as compared to 2 Rectifiers.

4. Is there any new chaemical available in the market to improve the quality of anodizing?

Looking forward to receive your reply as soon as possible.

Regards,

Rizwan Shaikh
Manufacturer - Mumbai, Maharashtra, India

Hi, Rizwan. Let me explain a principle here and then you may be able to decide for yourself how many rectifiers you need.

Rectifiers come in all sizes, so you could probably obtain one of sufficient ampacity to anodize a whole bunch of caps, if it was only a matter of capacity -- but it isn't. When you anodize, you must start at low voltage because a high voltage will cause too much current flow and will burn the parts. But as the anodized coating builds, you need a higher voltage to overcome the resistance to continue the anodizing. So if some parts are half anodized, you can't add unanodized parts to that cell.

If you set things up so that you anodize just one batch at a time, it's possible to do it with one rectifier. But most facilities with significant production will have something like a half dozen anodizing cells and will need a half dozen rectifiers. Good luck.

Regards,

Ted Mooney, P.E.  finishing.com Brick, New Jersey

Hello Rizwan
A single rectifier is more than enough. It depends how much productivity you want in a single cycle. You will have to adjust you anodizing tank accordingly.

Sumit Lodha
- Ahmednagar, Maharshtra, India