A question about the Electrode and the Tip.

[fante]

Hi:

May you tell how come the Tip of a plasma cutter torch doesn't melt away in spite of being the outlet for a 16000° C flame?
From what I have seen in some YouTube videos, the Tip or Cup is made of cooper. Or am I wrong?

Please help to clear this doubt.

Have a nice day.

 

[skotl]

Welcome to the forum!

I'm guessing here, but compressed air is leaving the tip at high pressure and igniting near the surface so I'd expect that the "flame" (not really a flame, but you know what I mean) is sufficiently far away from the tip (even by 1/2 a millimetre) to not melt the tip, and is constantly being blown away from the tip toward the workpiece.

It's the same reason that an oxy/acetylene torch does not melt itself; the hottest bit is away from the torch and pushing away from the torch.

 

[daleyd]

^^ I'd say as above, in the same way a brass nozzle doesn't melt away on a gas burner.

 

[Paul.]

modern air plasma electrodes usually use a hafnium electrode insert which has a very high melting point, around 2200deg c , older nitrogen plasma cutters use tungsten.

 

[fante]

Hi:

I really appreciate your answers and comments.
And it makes sense!!!.
So, the compressed air serves as a cooling system besides being the stuff which becomes a 'plasma'.

Thanx a lot.

 

[skotl]

Dunno if it's cooling it as such, more that it's "blowing the heat away". Plus, as Paul says, the tips made of expensive unobtainium

 

[Fazerruss]

Dunno if it's cooling it as such, more that it's "blowing the heat away". Plus, as Paul says, the tips made of expensive unobtainium

No I think you'll find Addamantium is much stronger.

 

[skotl]

No I think you'll find Addamantium is much stronger.

Charming, Prince

 

[T0rnado69]

one tip for you.

never rest the torch across your leg, while sitting in a car getting ready to cut the B pillar.

 

[v8burbling]

What did you do ?

 

[T0rnado69]

the torch turned as i moved to get myself into the right position.
and as the trigger is on the underneath of the torch.
the trigger pushed in and the plasma fired up for a few seconds and shot straight into my thigh.
putting a very deep hole, like i had been shot by a gun.
melted the skin a good 2" diameter around the hole.
was damm right painful and sore for a long time.
but on the good side the doctor said i didn't need any antibiotics
due to the intense heat of the plasma flame.
and gave me some painkillers and got nurse to dress the wound.

happy days, sure wont do that again i said.

 

[skotl]

the torch turned as i moved to get myself into the right position.
and as the trigger is on the underneath of the torch.
the trigger pushed in and the plasma fired up for a few seconds and shot straight into my thigh.
putting a very deep hole, like i had been shot by a gun.
melted the skin a good 2" diameter around the hole.
was damm right painful and sore for a long time.
but on the good side the doctor said i didn't need any antibiotics
due to the intense heat of the plasma flame.
and gave me some painkillers and got nurse to dress the wound.

happy days, sure wont do that again i said.

Jeez - that sounds no fun. I wouldn't have thought it would have sparked without being near earthed metal - do you know how/why it sparked?

Oh - and glad to hear you've escaped without serious damage - I'd be telling your grandkids that it was a bullet hole

 

[Spark plug]

Jeez - that sounds no fun. I wouldn't have thought it would have sparked without being near earthed metal - do you know how/why it sparked?

Oh - and glad to hear you've escaped without serious damage - I'd be telling your grandkids that it was a bullet hole

HF start, an earth isn't needed to establish the ark.

 

[T0rnado69]

nar it sure wasn't fun.
its something i wish not to try again ever.
as spark plug has said. HF start.
it will fire up for about 3 to 5 seconds and cut off it no earth is attached.

no grand kids yet, but hey maybe some day.

 

[skotl]

nar it sure wasn't fun.
its something i wish not to try again ever.
as spark plug has said. HF start.
it will fire up for about 3 to 5 seconds and cut off it no earth is attached.

no grand kids yet, but hey maybe some day.

Jeez - I'm glad mine doesn't have HF start, then!

And, in 40 years, you can proudly show off your bullet wound to the grandkids

 

[Jim Davey]

Jeez - I'm glad mine doesn't have HF start, then!

And, in 40 years, you can proudly show off your bullet wound to the grandkids

That's a good way to get on the sex offenders register.

 

[T0rnado69]

in about 40 years , il be 85 LOL

and IF im still about and there is grandkids about,
i wouldn't be able to show if off as a bullet wound anyway.
as its completely healed up now.

 

[Mr shiney]

They are a mini lightsaber!! I have done the same, straight through a finger. Went through the tip, flesh bone, glove!!

 

[NotANormalCoder]

When demonstrating plasma cutters to customers who have not used the process before, I always start by firing up the torch on a thick block of wood. The pilot arc very quickly burns a large hole in the wood. Then I tell them to consider the end result if you do this on skin. Point proved and the easiest safety lesson ever!

 

[skotl]

Cripes - I'm glad I've got a crummy cut50 with no pilot arc then!