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Proper Cut Direction

Share tips and tricks you know of in this forum. Plasma cutting, material handling, metal finishing, marketing, or anything that you feel is helpful.
jimcolt
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Proper Cut Direction

Postby jimcolt » Wed Sep 04, 2013 8:10 am

Think of cutting a ring, the inside diameter is cut counter clockwise, OD is cut clockwise. This provides the best edge squareness, and is due to the swirl pattern designed in the plasma torch.

The gas (air) swirl in a plasma torch does a few things, one of which is to help control edge squareness. If the torch was designed with reverse swirl rotation, then you could reverse direction on holes. There are some high end industrial plasma torches that have available reverse (CCW swirl) consumables. These are used in "mirror image" cut situations where two torches cut mirror image parts simultaneously. They are also used when you are cutting a flat plate into strips (bar stock) with two torches simultaneously......the torch on the left (driving away from you) will have standard swirl, the one on the right will have ccw swirl. This insures that both edges of the strip being cut will have the squarest edges.

I mentioned that swirl does a few things. Another very important function of gas swirl in a plasma torch is to increase nozzle life by improving the nozzle bore cooling. The air inside the torch gets superheated, however not all of the molecules are the same temperature, with the coolest being the heaviest. The swirl, properly engineered, slings the coolest air to the outside edges of the nozzle bore....effectively creating an insulating layer of cool gas. This makes the nozzle last longer. To make this work....the consumables must be manufactured of the correct materials and to very strict dimensional tolerances, and the air flow circuitry (pressure and flow) needs to work accurately and correctly. Now we know why Hypertherm genuine consumables last longer than others!

Some Hypertherm torches have a swirl ring designed with a dual swirl pattern, one swirl is designed to increase nozzle life, the other to improve edge squareness. This technology is used in high end oxygen plasma torches as used with high definition class plasma.

Jim Colt

CUT DIRECTION.png
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ben de lappe
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Re: Proper Cut Direction

Postby ben de lappe » Thu Jan 29, 2015 8:54 pm

Thanks for breaking it down scientifically, Jim. One question. When you speak of the cooler gas being forced to the outer edges of the swirl, does the cooling air have any effect on hardening the first few thousandths of material on the edges. Similar to heat treating? Or is it minimal with no real effect? The old metals tech in me says it may be possible.

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Re: Proper Cut Direction

Postby RevvedAC » Thu Feb 05, 2015 11:26 pm

I'm curious about the "heat tempering" or hardening as well.... I'm new to the plasma world having really only been using my table and Hypertherm 45 for a couple weeks now but I do find that when I undersize holes and go back to drill them out that sometimes they drill without issue, but sometimes they kill drill bits like none other.

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Re: Proper Cut Direction

Postby gamble » Fri Feb 06, 2015 10:33 am

what happens if you flip the swirl ring over like on a s45 torch, the orientation doesn't matter. Does your good side of the cut switch or stay the same?
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Re: Proper Cut Direction

Postby Bigdogbro1 » Tue Jan 19, 2016 2:52 pm

Hypertherm PM45 Plasma cutter

I remember it by thinking of a round wall clock and that the clock runs clockwise in relation to the clocks outer surface.

Just the opposite for inside cuts.
Last edited by Bigdogbro1 on Tue Feb 02, 2016 9:06 am, edited 2 times in total.

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Re: Proper Cut Direction

Postby Brand X » Tue Jan 19, 2016 3:25 pm

gamble wrote:what happens if you flip the swirl ring over like on a s45 torch, the orientation doesn't matter. Does your good side of the cut switch or stay the same?


With the S-45 torch you can change the direction of the swirl by flipping the swirl ring over.. Same with the Esab PT-31 torch.. You will need to mark your swirl rings to keep things consistence. I think it's a great feature in hand cutting... If you want to pull the torch, and you are left handed. it's a bit easier sometimes.. Suits me well.. So yes the good side changes to the other side of the cut,when you flip the swirl ring over..

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Re: Proper Cut Direction

Postby assai » Tue Jul 19, 2016 5:01 pm

Brand X wrote:
gamble wrote:what happens if you flip the swirl ring over like on a s45 torch, the orientation doesn't matter. Does your good side of the cut switch or stay the same?


With the S-45 torch you can change the direction of the swirl by flipping the swirl ring over.. Same with the Esab PT-31 torch.. You will need to mark your swirl rings to keep things consistence. I think it's a great feature in hand cutting... If you want to pull the torch, and you are left handed. it's a bit easier sometimes.. Suits me well.. So yes the good side changes to the other side of the cut,when you flip the swirl ring over..


Hi to all,
I'm a newcomer in plasma cutting world, please explain me in few words about swirl ring position for the Esab PT-31 torch. What position is "normal" for righ handed operator?
I live in Ukraine (Eastern Europe), in my country I have less information about plasma cutting on my native language=)) Thank you for your attention..

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Re: Proper Cut Direction

Postby Brand X » Sat Jul 23, 2016 9:44 am

There is nothing really written down in any Esab manual as to the proper orientation of the swirl ring.. I would just make a straight cut,pulling towards you, and see if the good side of bevel is on the side you want it.. If not, flip the swirl ring over.. You can note the direction, and always install it the same way..Use a permanent black marker,to make a mark on the swirl ring, so you can install it the same way every time..

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Re: Proper Cut Direction

Postby assai » Mon Jul 25, 2016 2:02 am

Brand X wrote:There is nothing really written down in any Esab manual as to the proper orientation of the swirl ring.. I would just make a straight cut,pulling towards you, and see if the good side of bevel is on the side you want it.. If not, flip the swirl ring over.. You can note the direction, and always install it the same way..Use a permanent black marker,to make a mark on the swirl ring, so you can install it the same way every time..

Got it!
thank you much!

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Re: Proper Cut Direction

Postby VPT » Wed Nov 30, 2016 8:58 am

Great post Jim! I never thought much about what direction to cut circles in. Now I am wondering, when converting to cut paths in plasmacam do they already convert in the right directions to work with hypertherm?


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