Unwinding of Fine Wires from Spools

We specialize in the manufacture of fine and super fine enameled copper wire.

Many of our customers have been complaining of wastage of the last 50 grams to 100 grams oin each spool, as it gets cut in the winding machines. This is mainly in sizes between 0.140mm and 0.070mm wire.

We use new PT-4 bobbins for these sizes. The problem is more with PU coated Wires. The VD is around 20. Please let ,e know if you have any information as to why this is happening. Could it be that the annealing is not sufficient??

Hello,

It is unlikely that anyone will be able to give you a solution to your problem from a distance.

The most important thing is to understand what changed in your process and then focus in on that. After that, very carefully make modifications and measure the results of the changes.

You have already identified that you are using new PT-4 bobbins and possibly that is when your problem started.

You already have the answers, you just have to ask the right questions.

At the sizes that you are talking about, i doubt that it is insufficient annealing. If I am calculating right you are talking of wire as small as 42-45 awg. At that size there are a lot of factors that can prevent you from getting all of the the wire off the spool. Also if I am calculating correct you are talking about coil winding speeds of nearly 1000 feet per minute.

So first off if it is getting cut in the winding machine, how is that your problem? It's not your winder.

Second if it is your problem, What is the flage to barrel ratio for the PT-4 bobbin. With fine wire, you want the ration to be low. For example a bobbing with a 100 mm flange diameter and 70 mm barrel would be a lot better than one with 100 mm flange and 50 mm barrel. If you have a bobbin with a high ratio then the increased tension due to the high ratio could cause the wire to break.

If there is the slightest flaw, burr or damage to the edge of the bobbin's flange, it could cause the wire to break.

Is the barrel of the bobbin tacky or sticky - some are to facilitate auto spool changes and when you are getting to the bottom of the barrel, tension again increases.

Also in some cases, the wire closest to the barrell is not spooled as nicely as later in the process. There could be wire entrapment,


At this size, and these speeds, it takes only a momentary hesitation of the derelling for the wire to break.

Thanks for the information. I will check the Flange to Barrel ratio, but back here in India, almost all Bobbins manufacturers have the same kind of mould for PT-4 bobbins.

We do put some Gum on the Barrel of the Spool as Bobbin Change takes place at a high speed, but a layer of paper is put on the gum after the wire sticks, so that the next few layers of wire do not get stuck.

You have indicated various reasons pertaining to the Bobbins/Spools. Could there be any property of the wire which could be causing such problems??

Any info will be of great help. Thanks!!

Mr. Sundaram, how is your problem? what awg wire do you make that is fine and super file.