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If you have a question regarding coaxial, telephone, and building wire, power cable, insulation, extrusion, bunching, stranding, braiding, etc. post it here.

TOPIC: Insulation of enameled copper wire

Re: Insulation of enameled copper wire 2 years 8 months ago #782

Tech1. How is the specialty enamelled wire business these days. Do you do the water test? rb
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Re: Insulation of enameled copper wire 2 years 8 months ago #783

What the industry would call it is a wet dielectric test. Everyone needs to understand a few basic things about flattening round coated wire when it comes to any kind of dielectric properties. Firstly like the comments already been made that stressing the polymer when flattening will degrade it. Secondly and most importantly the thickness values of the polymer is a different percentage than when it was round therfore reducing the the dielectric strength of the polymer along the surface area of the wire ( think of it as a bi metal ). Even though the bi-metal has a certain percentage of one alloy on the outside of it a one size, when reduced to another size the percentage stays the same but the thickness is decreased. this is basic math and should be a known when manufacturing coated round wire and flattening it.Other things such a poor flattening processes can affect dielectric strengths as well.One last thing would be the coated round wire quality. If it's poor, it's never going to work properly. A seasoned engineer taught me once that it's not always the process that your working on but 4 processes before that is causing the trouble.
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Re: Insulation of enameled copper wire 2 years 8 months ago #784

Tech1, You are absolutely right. You cannot abuse the wire, which is what post rolling does, and expect it to meet "new" wire specs.

You are also right on about process engineering; the problem you are working on probably originates a couple of processes prior to where you identify the problem.

Post rolling or flattening round wire creates some inherent problems that by necessity mitigate your origial standards. You cannot apply round wire standards or sahped wire standards to an enamelled wire that has been flatened or post rolled to a size that is different than the original size!

You have made a "specialty wire" and it requires specialty specs.

rb
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Re: Insulation of enameled copper wire 2 years 8 months ago #785

Thanks spectre07 and tech1
But do you know about this special specification (min. accepted values for tests) for flat wire, or we can compare the test results for flat wire with the values from the standards for rectangular wire?

Raul
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Re: Insulation of enameled copper wire 2 years 8 months ago #786

raul,
when you are making "off spec" or specialty wire sometimes the only thing that you have to go by is what the end user tells you what measurement they wants the wire to meet.

We used to make a polyimide wire that the enduser called 46 awg. He had four different specs for resistance but at the same time had to stay withing the dimensional specs for 46 awg. We did it but it waa not easy.

If the customer provides the spec he cannot realistically require you to hold to a rectangular shaped wire spec if you are not making that wire.


I know that you said you could not coat shaped wire because of you equipment but I really think that a way to do it would be to put your post rolling machine between the annealer and the applicator. You would have to take some action to prevent the wire from rotating but I know some technicians that could do.

I don;t know what type post rolling machine you have but a very small turks head from BHS-Torin would work.


rb
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