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Shiny spots on enamelled copper wire

7 years 1 month ago #1776 by Archived Forum Admin
Recently I have been facing a problem of shiny spotting during coating of copper wire in my enameling plant.

I have 12 head vertical unit. Though one can see the shiny spots on the wire, there is no difference in any other property.

So I need some advise on solving this problem.

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7 years 1 month ago #1777 by Archived Forum Admin
Hello Harbeer,

Because you live in a hot and humid country we first wonder about a few small items that may help us better understand your particular situation;

1) Do you purchase your enamel from a major manufacturer?
2) Is the enamel you are using right now past its shelf life:?
4) Is the enamel that you are using hygroscopic?
5) is your enamel supply open to the air? Make sure that the supply is sealed. Put a lid on the supply tank if there is none. Never leave enamels exposed to the atmosphere.

I have contacted a magnet wire specialist and hopefully he will post a note here shortly.

Peter J. Stewart-Hay
Stewart-Hay Associates
519 641- 3212

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7 years 1 month ago #1778 by Archived Forum Admin
These shiny spots are called “fish eyes”. They are caused by contaminants in the enamel. The contaminants can come from residual wire drawing lubricants, contaminants in the enamel, your tanks or method of handling the enamel, dirty annealer tubes, dirty sheaves (lubricants from bearing getting on sheaves), dirty wipes, something in the air.

I know of an auto factory that had a problem with “fish eyes” in the painted cars. The problem only occurred on the day that the employee cafeteria cooked fried chicken. Somehow the kitchen exhaust, heavy with the odor of fried chicken was contaminating the paint shop air. Remember if you have smoke or smell something then you will have microscopic particles in the air. If those particles are “oily” and can come in contact with the wet (with enamel ) wire, you could get “fish eyes.”

One solution is to start at the payoff and clean the machine and regularly change the wipes.

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