Elongation of copper

What is the optimal elongation of copper when paying out of a coil?

Hello crb1214,

I think you have to give us more information.

When you say "Paying out of a coil" what exactly what you mean? Is it the coil from a vertical or horizontal (Elephant trunk design) drop coiler on a rod breakdown machine? These satisfactorily let off 13 gauge wire with no problems at all for telephone wire intermediate drawing and tandemized extrusion.

What gauge size wire are you talking about and at what is the maximum speed of the pay off wire? Likewise are you letting off vertically or horizontally?

Thank you.
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641- 3212

The coils are vertical from our rod machine. WE run 10, 12 and 14 AWG copper. Line speeds are 1500 FPM. Any help would be appreciated.

Hello again.

I am going to guess that you are getting occasional kinking of the (hard drawn?) wire as it is let off vertically for say a downstream intermediate drawing and annealing operation. Hard drawn wire should be all right. One important thing is to have sufficient height to the closing position (guide die) above the coil. Another of course is to have the coil properly centered.

It is really difficult for me to visualize exactly what you have but I presume that there is some sort of overhead smooth guide cone made of steel rod with a ceramic or carbide oversize guide die at the center and a pulley above that to guide the wire away. There may be some sort of tension device between the oversize guide die and the pulley and there are probably two secondary guides (pigtail design or dies) to prevent the wire from jumping off the pulley.

The whole pay off should also be fenced and interlocked to prevent someone from being caught in the pay off wire when the machine is running.

When the hard wire comes up the stem, it should always look like a proper helix but remember that the stems must not be damaged or bent as there cannot be any jerking action. As the coil then proceeds in air towards the guide cone above, the helix needs to collapse naturally (smoothly) so that kinking does not occur.

That is about all I can say from afar and without drawings or pictures.

Regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641- 3212

Another concept:

Perhaps you are talking about 10, 12 and 14 gauge finished wire in the pay-off and that it is used in the manufacture of building wire.

If that is the case, then the final properties of the conductors, including elongation, have already been set. This then would then mean that the whole discussion is rather meaningless.

Regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641- 3212

Unless you have very annealed wire and excessive distance from payoff to machine entrance or too much back tension at payoff which might stretch the wire and cause it to break, I'm not sure why elongation would be an issue as you are drawing the payoff wire to a smaller size anyway.