Springback

You wrote:

"Read the threads but I did not get the exact answer. We have hard wire, our elongation is from 30-38%. for sizes from 0.300mm up to 1.300mm. but we have poor ductility. our parameters are:
- Horizontal line with inline drawing
- Annealer oven length is 10m. 2 zones . temperature of annealer is 400C..
- Enameling chamber is 500C. and for example for 0.75mm production speed is 50."

First you should be supplying your inline drawing machine with soft or annealed wire. If it is hard, your can draw it but you will not be able to anneal if sufficiently based upon grain structure. It might pass elongation and spring back but grain structure wise it will not be fully annealed.

Also when inline drawing you must reduce the wire at least 30-35% and no more than 80%. That means that a single supply wire may not be suitable for all desired finished sizes.

Your speed of 50 is a DV of about 37. I assume 50 is in meters per minute . In most inline systems I've used, we used as recommended soft inlet wire. The pre-annealer was just that, a pre-annealer and used more to clean the wire than anneal it. With the proper 30-80% reduction in size, the enameling oven did the real annealing.

I think your problem lies in supplying hard wire to the inline drawing machine, then trying to anneal it at too low a temperature. Again you are getting good elongation and possibly spring back but you have wire that has irregular grain pattern. If it was processed right, you would have a higher tensile strength wire, better spring back, and the coil winder could increase winding tensions without stretching or elongating the wire.

Hope this helps.

Thank you
I read that the enameling oven do the real annealing, so if we increase enameling oven temperature we will get better annealing?

I am not sure if you fully understand the Inline process. I am not a metallurgist but the more your cold work the copper the more fractured and irregular and smaller the grain structure becomes. The Inline drawing is intended to reduce the number of supply wires that you need to make specific finished wire. Without inline drawing you need a supply reel that is the same size of the desired enameled wire. If your machine is a 6 head machine and can finish 10 different sizes, you will need 60 payoff reels to run all of those sizes. With inline drawing you might only need 2 different sizes to provide 10 finished sizes.

Your pay off package can be larger because the wire will be larger and then drawn to the desired size. Since the inline machine does not operate at as high a speed as a break down machine, the grain structure is not disturbed (fractured) as badly as on a high speed drawing machine. Also since the input should be soft, the grain structure is larger. This allows the annealer to be a pre-annealer and primarily clean the wire. Annealing will then take place in the oven. Because properly provided inline drawn wire has larger grain size, the structure is more organized, when processed the finished wire will have near perfect grain structure, size, etc. resulting in an enameled wire that has good elongation, a higher tensile strength, and good springback.

I know this explanation is an oversimplification of the metallurgical process but it works. If you have continued problems, I would do the following: insist that the copper provider give you paperwork documenting the quality of the rod. the next thing I would do is refer to my inline equipment manual and follow it or contact the equipment provider and ask them for assistance.

I have always found that when you have problems, get back to the basics. Then document changes you make as you work to improve the problem(s). Never implement multiple corrections without confirming which ones work.