Matching nozzle size to amps? Pros and cons?

Information on plasma cutting nozzles, electrodes, and other consumables.
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BlueRidgeFab
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Matching nozzle size to amps? Pros and cons?

Post by BlueRidgeFab » Thu Nov 05, 2020 11:09 pm

What are the pros and cons of using a higher rated nozzle at a lower amp setting?
For example, are there any negative consequences to using a 60 amp nozzle for cutting at 40amps?

adbuch
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Re: Matching nozzle size to amps? Pros and cons?

Post by adbuch » Fri Nov 06, 2020 4:08 am

I am not aware of any reason to use a 65 amp nozzle for cutting at 45 amps. I am guessing that the larger nozzle will create wider kerf widths, and perhaps not keep the plasma arc as focused as using the correct size nozzle. For 65 amp cutting, Hypertherm recommends the following consumables and settings.
Hypertherm 65 A shielded consumables.jpg
65 A Shielded Mild Steel Cut Chart.jpg
For 45 amp cutting, Hypertherm recommends the following consumables and settings.
Hypertherm 45 A shielded consumables.jpg
45 amp Shielded Mild Steel Cut Chart.jpg
It is also generally recommended to use the lowest current setting with matching consumables that will cut a given material. For example, cutting 3/16" mild steel at 45 amps would generally produce better results than at 65 amps (see cut charts for settings). Less current equates to less heat into the material, less warping, and a narrower kerf width with better detail in the cutting.
David

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weldguy
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Re: Matching nozzle size to amps? Pros and cons?

Post by weldguy » Fri Nov 06, 2020 9:42 am

There are no pros that I know of, cons are wider kerf, arc intensity will not be as focused as Daid mentioned. I would just choose the lowest amperage for a given material thickness and use the proper consumables for that amperage for best results.

ScottRa
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Re: Matching nozzle size to amps? Pros and cons?

Post by ScottRa » Fri Nov 06, 2020 12:30 pm

Ok, this kinda brings up something I’ve wondered along these lines. The PM65 goes down to 20 amps and the PM85 goes down to 25. Is there some reason they don’t make lower amperage nozzles for cutting the real small gauges like 16 through 26 where the travel speeds get high? Just seems like you could get better detail and less warping. Are there physical limitations on how small you can make a plasma stream or is there not enough demand in those thin gauges?

Scott

BlueRidgeFab
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Re: Matching nozzle size to amps? Pros and cons?

Post by BlueRidgeFab » Fri Nov 06, 2020 10:09 pm

Great info! Thank you all so much! It appears it’s best to match material with amps with matching nozzle. I appreciate the help.

adbuch
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Re: Matching nozzle size to amps? Pros and cons?

Post by adbuch » Fri Nov 06, 2020 11:25 pm

ScottRa wrote:
Fri Nov 06, 2020 12:30 pm
Ok, this kinda brings up something I’ve wondered along these lines. The PM65 goes down to 20 amps and the PM85 goes down to 25. Is there some reason they don’t make lower amperage nozzles for cutting the real small gauges like 16 through 26 where the travel speeds get high? Just seems like you could get better detail and less warping. Are there physical limitations on how small you can make a plasma stream or is there not enough demand in those thin gauges?

Scott
Scott,
Here is the Hypertherm cut chart for Low Speed, FineCut, Mild Steel. 20 thru 26 ga. sheet metal would be cut at 30 amps, but using the FineCut 45 amp nozzle and swirl ring. It is possible that a setting of 20-25 amps may be useful for cutting material thinner than 26 ga, or for hand cutting of thin material. I routinely use my PM85 for cutting 22 ga. mild steel and cut at 30 amps/150 ipm per the cut chart using FineCut consumables. I don't know why lower amperage nozzles are not produced by Hypertherm. Jim Colt would be the person to answer that question.
David
Low Speed FineCut Mild Steel Cut Chart - Hypertherm.jpg

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