cut speed 45 vs 65

mr.jake519 · Post by **mr.jake519** » Fri Mar 13, 2020 12:29 pm

Why is the cut speed using 45a on the powermax 65 higher than using powermax 45?
Eg: powermax 65 using 45a consumables 16g is 350ipm

powermax 45 16g is 249ipm

Being as amperage is the same i cant wrap my head around the 100ipm increase???

Im trying to setup cut charts in sheetcam for powermax 65. Id prefer to cut 16g at 250 as usually doing fine detail in 16g.

Post by **acourtjester** » Fri Mar 13, 2020 1:36 pm

Just follow the 65 manual for the chart basics, but you should also run some tests to fine tune things. If you are using a THC you really need to run tests for minor differences in the electronics. Here is a video about the testing, this with a Price ACHV-10 THC and my Hypertherm 65 on my DIY table.

mr.jake519 · Post by **mr.jake519** » Fri Mar 13, 2020 1:53 pm

I have my thc working good, i just do a straight line test cut and check the data plot to see where i need to set it.

Do you cut 16g at 350ipm? My machine will do it just seems quite fast for detailed stuff

Also do you know why there is the difference between powermax 45 and 65? Duty cycle perhaps?

Post by **weldguy** » Fri Mar 13, 2020 3:07 pm

mr.jake519 wrote: ↑Fri Mar 13, 2020 12:29 pm Why is the cut speed using 45a on the powermax 65 higher than using powermax 45?

That does seem odd, I know what you mean, 45 amps is 45amps. It must have something to do with the design of the torch and consumables.

mr.jake519 · Post by **mr.jake519** » Fri Mar 13, 2020 3:11 pm

I agree, im more curious than anything. Maybe master plasma guru Jim Colt will chime in!!

Post by **acourtjester** » Fri Mar 13, 2020 6:00 pm

Yes on the straight line tests for each thickness of metal and nozzles.
I know the manual states 16 Ga 45 amp nozzle 350 IPM I just don't run that fast get great cuts.

Post by **robertspark** » Sat Mar 14, 2020 6:58 am

weldguy wrote: ↑Fri Mar 13, 2020 3:07 pm
mr.jake519 wrote: ↑Fri Mar 13, 2020 12:29 pm Why is the cut speed using 45a on the powermax 65 higher than using powermax 45?
That does seem odd, I know what you mean, 45 amps is 45amps. It must have something to do with the design of the torch and consumables.

.... You are forgetting the effect of voltage....

Amperage does not cut steel.... Power does (volts X amps)

The pmx65 has a higher power rating (volts X amps) so in order to keep the volts correct (torch height) the machine has to move faster.

I haven't got a number for plasma cutting but for welding steel the magic number to weld steel is 1A per 0.001" (39A-40A per mm) of material thickness... Plasma is similar in that you need a certain amount of power to cut metal of a certain thickness..... The amperage is fixed so the way we adjust the voltage is move the machine quicker for thicker material or slower for thinner material.

There is also the effect of the nozzle too.... Less so with the newer machines as they use the same consumables but the effect is still there ...... If you compare the pmx45 non XP with the 45xp and the 65 85 105 and rival machines. This gives the power density (amps per sqmm or amps per square inch)

This effect also explains whey as the nozzle gets worn and bigger the power density goes down and you may need to slow down the cut a bit.... But the kerf will obviously get wider more bevel etc etc etc

mr.jake519 · Post by **mr.jake519** » Sat Mar 14, 2020 8:17 am

Excellent Robert! Thanks for the great explanation.

Post by **robertspark** » Sat Mar 14, 2020 9:35 am

here are some tables (I was bored + curious....)

note + consider nozzle part numbers, and air consumption + air pressure set at regulator.

1/4" mild steel, shielded consumables, all machines set on 45A

10 Gauge (0.135"), shielded consumables, all machines set on 45A

Old Iron · Post by **Old Iron** » Sat Mar 14, 2020 1:16 pm

Robert, the question I come up with is, PMX 65/85 the air pressure says 85 psi and I thought 72 psi was the suggested?
Does 85 psi give a better cut?

Post by **robertspark** » Sat Mar 14, 2020 1:32 pm

85psi in the book

I am not sure where lower is suggested

85 should give a smaller denser plasma gas .... Too low and you risk the pierce not being good and angularly issues in my hobbist opinion ....

Post by **djreiswig** » Sat Mar 14, 2020 4:25 pm

Old Iron wrote: ↑Sat Mar 14, 2020 1:16 pm Robert, the question I come up with is, PMX 65/85 the air pressure says 85 psi and I thought 72 psi was the suggested?
Does 85 psi give a better cut?

I think you might be confusing the inlet pressure with the pressure setting in the cutter. The inlet should be above 90 when cutting. You can adjust the pressure setting or leave it on automatic. It's based on the length of the torch lead. The longer the lead the higher the pressure. I use 71 on my 35' lead. I have the RS-485 port so I adjust the settings with SheetCam. I discovered if you use it to set amps you have to program the air pressure also.

Post by **robertspark** » Sun Mar 15, 2020 2:16 am

Extracts from the manual.... What works for you works for you

71psi is probably a bit low.... But if it works for you it works!!!

I have not worked it out but the variance is probably quite low between 71 and 75 psi

Here you go you can work it out for yourself. You will need to find the orifice diameter via iteration first.... Then play with the numbers to see the change

https://www.tlv.com/global/UK/calculato ... ifice.html

Post by **djreiswig** » Sun Mar 15, 2020 5:24 am

Jim Colt is the Hypertherm expert. You can find several posts here where he recommends not running under 90psi.
viewtopic.php?f=60&t=27756&p=167942

And here's a post of his recommending air pressure settings for different lead lengths.
viewtopic.php?f=4&t=16094&p=92673

Your chart is for inlet pressure, not the actual pressure setting in the unit. They are different. If you leave the air pressure setting on auto, then it will be set based on which length lead you have attached.

Post by **robertspark** » Sun Mar 15, 2020 5:55 am

I took it from the pmx65 operator MANUAL.....

The extracts ARE from the operator manual....

I am not making this stuff up. It is from the official hypertherm powermax 65/85 operator manual, link below.

I have not questioned Jim Colts knowledge or anything he has said.

Most of what Jim says is along the lines of .... Use the book specs.... As hypertherm have a whole R&D department spending hours testing settings to arrive at a set of recommendations.

Download + RTFM .... VVVV revision 4, April 2018

https://www.google.com/url?sa=t&source= ... 4c6_0Rj2Bd

Post by **robertspark** » Sun Mar 15, 2020 6:06 am

+ that is a bit of an oddball post... Someone trying to make a duramax torch run with a thermal dynamics machine....

Post by **djreiswig** » Sun Mar 15, 2020 11:49 am

I agree with you. Go by the manual, but I think those are just minimums.
I have not been able to find it quoted in the manual what the actual cut pressure settings should be for the different torch lead lengths. Do you have this information? I'm just going off of the post from Jim for that information.

Old Iron · Post by **Old Iron** » Sun Mar 15, 2020 2:19 pm

Thanks for the replies.
I think we may be talking two different things here.
Inlet pressure vs cutting pressure.
I'll bow out

cut speed 45 vs 65

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