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Hello,

I have 12000 meters of 4mm diameter copper wire. It is pure 99,9% copper. Unfortunately it is too soft for what i want to use it for.

How can i harden it ?

I have seen many ways on the web but none is adapted to such a large quantity. Please help.

Thank you

 

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Copper is non-ferrous and can't be hardened with heat. Really the only way to do it is to work harden it. Most people do this by simply beating on it for awhile. Then it can be heated up to soften it.

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What are you trying to do?  You can melt it down and alloy it up to something significantly harder.  If you need it to stay as 4mm wire, I think your best bet would be to set up a series of roller drums to pass the wire over.  As it gets wound and unwound repeatedly it will work harden.  

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Or you can try age-hardening, which is heating to around 220 degrees C and holding for an hour or two.  Work hardening is far better, though.  And pure copper will never get very hard.

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What about doubling the wire and winding it, like for a wire-wrap handle. That'll provide some hardening. But again, if you need it to stay in its current dimension that won't work.

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10 hours ago, Brian Myers said:

Copper is non-ferrous and can't be hardened with heat. Really the only way to do it is to work harden it. Most people do this by simply beating on it for awhile. Then it can be heated up to soften it.

Hi Myers

Thanks

Beating would work for a small amount of copper but i have 36,000 feet of wire

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10 hours ago, Jerrod Miller said:

What are you trying to do?  You can melt it down and alloy it up to something significantly harder.  If you need it to stay as 4mm wire, I think your best bet would be to set up a series of roller drums to pass the wire over.  As it gets wound and unwound repeatedly it will work harden.  

Hi Miller 

Thanks for your reply

i think i will go for the roller drums as this method does not need a factory or a foundry

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10 hours ago, Alan Longmire said:

Or you can try age-hardening, which is heating to around 220 degrees C and holding for an hour or two.  Work hardening is far better, though.  And pure copper will never get very hard.

Hi Longmire

 

Thank you for your reply

 

Yes i start to understand that unless i go for alloying i will never get a hard wire but i have to stick with pure copper as this is for an AM antenna feeder. As you know, pure copper has the best electrical conductivity especially when we have long runs of 2,000 feet

 

What about combining age-hardening then bending ? Or is there a limit to the hardness of pure copper ?

 

Anyway i will give it a try on a small amount (100 feet) then see what happen

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10 hours ago, steven smith said:

i like jerrods idea of winding, i dont think that would change the size of the wire much if at all. 

 

you can also twist it but i dont know if that would make it thinner, i think it might though.

Hi Smith

 

Thank you for your reply

 

Yes it seems that bending gives the best results but i will try to apply two or three methods on the same sample to see what happens...

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6 hours ago, Brian Myers said:

What about doubling the wire and winding it, like for a wire-wrap handle. That'll provide some hardening. But again, if you need it to stay in its current dimension that won't work.

Hi Myers

 

Yes i need to keep the 4mm diameter

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Oddly enough I have some experience work hardening copper wire this size.  I had a project once where I had to make test loops of wire about 20' long and run them continuously around a pair of sheaves.  After just a few minutes of running at about 100 feet per minute, the wire would work harden to the point that it broke.  The sheaves were about 24" in diameter. 

 

Ultimately I spent a lot of time Tig welding new loops together so my team had enough specimens to test.

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Posted (edited)
20 hours ago, Brian Dougherty said:

Oddly enough I have some experience work hardening copper wire this size.  I had a project once where I had to make test loops of wire about 20' long and run them continuously around a pair of sheaves.  After just a few minutes of running at about 100 feet per minute, the wire would work harden to the point that it broke.  The sheaves were about 24" in diameter. 

 

Ultimately I spent a lot of time Tig welding new loops together so my team had enough specimens to test.

Hi Dougherty

Thanks for your reply

So i need to do the run about 10 to 20 times

I will try it

As I said it is for an AM radio station. The 4mm copper wires runs for 2000 feet between 600kW Transmitter and Antenna tower

Birds such as buse and hawk land on the wires and break them so I need to harden the copper wire 

IMG_0028.JPG

Edited by sidate
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In jewelry making, twisting wire is a standard method of getting it to harden.  It will shorten the wire to some degree and also increase its diameter slightly.  Another method is to pull it through a well lubricated draw plate but this decrease the diameter.  Be aware that wire hardened in these ways, commonly called work hardening, will also make it a bit more brittle and will be prone to cracking or breaking if worked more, as in bent or forged.

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Ah, it doesn't need to be hardened, it needs to be supported. You would need a non-conductive support, some type of cord run from spot to spot, then lightly wrap the wire around it. The cord will support the wire and any birds that land on it. Para-cord would work great, but could get a bit expensive, maybe a heavy sisal cord or light rope.

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I was thinking some 3/8" steel cable.  Tie the copper wire to it every few feet and you're good to go.

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3 hours ago, Alan Longmire said:

I was thinking some 3/8" steel cable.  Tie the copper wire to it every few feet and you're good to go.

I thought cable too, but I didnt know if that would interfere with the copper's ability to act as an antenna. 

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8 hours ago, Brian Myers said:

I thought cable too, but I didnt know if that would interfere with the copper's ability to act as an antenna. 

A cable would be 316L stainless steel which is quite expensive (12,000m)

That would be my last choice. I will try hardening the wire today and test it to see what happen

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Today I tested most of the ideas.

Twisting, drawing and bending are good.

Then I stretched 60 feet of soft copper wire to 500 lbs (Turnbucckles and Dillon dynamometer)

After releasing the stress on the wire it was quite hardened

Tomorrow I will do some more tests

 

 

20200413_104319.jpg

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What frequency are you broadcasting?  I'm surprised to see the feeder is a single wire rather than coax or hard line.  Then again 12,000m is a long way to get to the antenna...

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Just remember one thing, this hardened copper will be very brittle. Even wind blowing over it will cause it to flex and break at stress areas like where it's attached after awhile.

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1 hour ago, Brian Dougherty said:

What frequency are you broadcasting?  I'm surprised to see the feeder is a single wire rather than coax or hard line.  Then again 12,000m is a long way to get to the antenna...

Frequency is 500kHz to 1200kHz.

Power can go up to 1200kW. 

The Andrew 4 inches Coaxial cable price is 40$/feet so it is 72,000 USD for 1,800 feet.

A copper wire feeder is made of 12 wires : total cost : 15,000 USD for the same length 

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Actually there are 4+8=12 wires as you can see on the 1st picture.

4 wires for the central "hot" part.

8 wires for the shield which is connected to earth.

Total distance is 1,800 feet

Total copper wire used 12x1,800=21,600 feet

The remaining wire is for replacement in case a wire break which will happen anyway (wind, trees, birds)

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That's pretty cool.  I've got some ham buddies that'll get a kick out of your pics if you don't mind me showing them.

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