Wire Coating

Q. First of all thank you for your valuable articles on PFOnline and efforts to help the painting industry. I have read your articles, which include "Coating Wire" in Oct. 2005, and "Coloring Galvanized Wire" in Nov. 2007. We want to coat our wire (0.80 mm diameter) with a high viscosity UV ink as a thin layer (~20 µm). You have suggested in your article to use a 'wire tower.' Are there sample drawings or pictures of this system? Currently our line is running on a horizontal sequence. Is there an applicator by which we can paint the wire in a horizontal position?

And lastly, on your article about coloring galvanized wire, you have added that we can find suppliers of such machines in the Products Finishing Directory. I don't have the printed version. Can you please advise the online pages where it can be found? G.T.

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A. The following is a simplified description of a vertical wire tower:

1. Wire coming off a pay-out spool passes under a sheave and up through a small trough of coating material.
2. As the wire exits the trough, it passes through a circular die where the coating is reduced to an even film at a controlled thickness.
3. The coated wire ascends vertically through an ozoned oven, which flashes-off any solvent and cures the film.
4. At the top of the oven, the wire passes over a sheave and descends to and passes under a lower sheave.
5. To get enough film build, the wire ascends through the trough and successive dies and up through the oven multiple times. The diameter of each successive die is increasingly larger so as to apply another layer of wet coating each time before it rises to be cured in the tower.
6. After the final coat is cured, the descending coated wire passes under the last lower sheave and is fed onto a take-up spool.

To find suppliers of Finishing Systems, go to www.pfonline.com and click on "Suppliers" under the banner. Type Finishing Systems in the 'Search by Product' box. When product categories appear, click on "Finish Systems, Paint, Porcelain Enamel, etc." and this will give the aforementioned list.

(Note: The direct URL for this page is www.pfonline.com/dp/pfd/SuppliersDatabase_Detail.cfm?ID=3390.)

Since there are commercial wire towers applying UV-curable coatings to magnet wire, suppliers of UV coatings and UV radiation sources should be able to help you. On the other hand, I believe you can coat your wire horizontally since you will be applying a fast-reacting UV-curable coating. I suggest you consider passing your wire through the small trough and circular die setup to control film thickness.