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Posted by Ignoramus27153 on June 2, 2006, 12:05 am
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Could anyone say what is the proper plasma cutting sequence? How about
this:
when trigger is pulled:
- open air valve for a certain amount of time (like 0.25 sec)
- Then start current
* When arc voltage is above certain value, turn on HF, turn off HF if
voltage drops below that
When trigger is released:
- stop power
- keep air valve open for a period of time, like 5s
does it make sense?
I am programming my microcontroller, which I mostly did for stick and
tig (proper relays are closed when they should be), but I have no idea
what to put in for plasma.
thanks
i
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Posted by Carla Fong on June 2, 2006, 12:37 am
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Ignoramus27153 wrote:
> Could anyone say what is the proper plasma cutting sequence? How about
> this:
>
> when trigger is pulled:
>
> - open air valve for a certain amount of time (like 0.25 sec)
>
> - Then start current
>
> * When arc voltage is above certain value, turn on HF, turn off HF if
> voltage drops below that
>
> When trigger is released:
>
> - stop power
> - keep air valve open for a period of time, like 5s
>
> does it make sense?
>
> I am programming my microcontroller, which I mostly did for stick and
> tig (proper relays are closed when they should be), but I have no idea
> what to put in for plasma.
>
> thanks
>
> i
>
I've never measured what our machine (Hypertherm) does, but that
certainly sounds like what the sequence is.
I think the post cut air purge is 8 seconds on ours... Probably just
enough time to cool the torch components. Likely not a critical value.
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Posted by Ignoramus27153 on June 2, 2006, 12:50 am
Please log in for more thread options wrote:
>
>
> Ignoramus27153 wrote:
>
>> Could anyone say what is the proper plasma cutting sequence? How about
>> this:
>>
>> when trigger is pulled:
>>
>> - open air valve for a certain amount of time (like 0.25 sec)
>>
>> - Then start current
>>
>> * When arc voltage is above certain value, turn on HF, turn off HF if
>> voltage drops below that
>>
>> When trigger is released:
>>
>> - stop power
>> - keep air valve open for a period of time, like 5s
>>
>> does it make sense?
>>
>> I am programming my microcontroller, which I mostly did for stick and
>> tig (proper relays are closed when they should be), but I have no idea
>> what to put in for plasma.
>>
>> thanks
>>
>> i
>>
>
>
> I've never measured what our machine (Hypertherm) does, but that
> certainly sounds like what the sequence is.
Thank you.
It's OK, the numbers could be fudged with, I just need to get the
sequence right. I already programmed this particular sequence (with
delays and voltage thresholds as parameters)
> I think the post cut air purge is 8 seconds on ours... Probably just
> enough time to cool the torch components. Likely not a critical value.
Sounds good, I will change my value from 5 to 10 then.
A ignorant question, do plasma cutters need only air? (no second gas
going through another line)?
i
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Posted by woodworker88 on June 2, 2006, 9:52 am
Please log in for more thread options The purpose of the post cut purge is to cool the torch components
significantly. Since in a plasma torch the arc is contained within the
nozzle if you shut off the air, you will have a puddle of copper
electrode in the tip. I think mine depends on the time the torch has
been on, but I have heard it go on for as long as 30 seconds. Makes
sense, the hotter the torch, the longer it should run.
Plasma cutters need only a compressed gas to plow the hot metal out of
the cut. Obviously the most economical is clean, DRY compressed air
but professional plasma cutting often uses dry nitrogen instead (no
oxidation when cutting Aluminum or Stainless). I've never heard of
anyone plasma cutting with shielding gasses (argon,etc).
> It's OK, the numbers could be fudged with, I just need to get the
> sequence right. I already programmed this particular sequence (with
> delays and voltage thresholds as parameters)
>
> > I think the post cut air purge is 8 seconds on ours... Probably just
> > enough time to cool the torch components. Likely not a critical value.
>
> Sounds good, I will change my value from 5 to 10 then.
>
> A ignorant question, do plasma cutters need only air? (no second gas
> going through another line)?
>
> i
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> this:
>
> when trigger is pulled:
>
> - open air valve for a certain amount of time (like 0.25 sec)
>
> - Then start current
>
> * When arc voltage is above certain value, turn on HF, turn off HF if
> voltage drops below that
>
> When trigger is released:
>
> - stop power
> - keep air valve open for a period of time, like 5s
>
> does it make sense?
>
> I am programming my microcontroller, which I mostly did for stick and
> tig (proper relays are closed when they should be), but I have no idea
> what to put in for plasma.
>
> thanks
>
> i
>