Hi All..

We produce 20AWG electro-plated tinned copper wire and then proceed by heating with an electric oven at 135 degrees C for 6~12 hrs. Recently our inspection showed that the wire elongation has changed when compared with year 2007 (2007/12= 4.75%, 2009/12= 24.5%). Will the property of the wire drastically change when we heat at 135 degrees C for 6~12 hrs? Can anyone give me the data of elongation vs temperature vs (time)?

Thanks and regards
Berman

Hello Berman,

We really do not what to tell you because the information you have given is so very minimal.

When you talk about heating in an electric oven at 135 C (275 F) for 6 to 12 hours we have no understanding at all.

1) Is the copper ETP?
2) Was the wire previously annealed, say after rod breakdown? If not at rod breakdown, what was the % reduction in area before the first annealing process or is 20 gauge the first and only anneal?
3) Are you talking about "X" number of annealing spools filled with tinned coated wire and then properly stacked in the electric oven?
4) What is the atmosphere in the oven and is the atmosphere moved by fans to ensure that all corners of the annealer receive the same degree of heat?
3) Does your stated time include the time to bring all the conductor on all the reels to 135 C? (Soak time)
4) What guidance were you given by the annealer manufacturer?
5) Have you done any experimentation at your annealer?

It seems to us that there are two issues here.

1) The capability and competency of the annealer itself.
2) The way the conductor is placed in the annealer. (Weight, number of reels and positioning.) Consider load repeatability a very important factor.

Then get back to the way you were doing things in 2007 and confirm the elongation, assuming of course you are looking for 4.75% elongation.

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

What is the purpose of heating it in an oven. I'm no metallurgist but I think that you could heat it for a long time at 135C and not have any major change in the characteristics of the conductor.

My guess would be that the copper you are processing today is different than the copper you were processing 3 years ago.

In 2007 were you drawing from rod to 20 AWG and now having an intermediate anneal at about 8 AWG and then drawing soft wire to 20 AWG?

Like Peter says there is not enough info to give a reasonable answer.

RB