Cut quality - hypertherm 85

[Cracker Red]

Trying to dial in my LDR table, cutting 11 gauge steel

Air supply has prefilter, refridge/dryer, post filter, regulator, 85psi input to plasma
Torch parts - 45amp fine cut, fresh parts

Using the book setup, 45amp 84 volts @ tip, THC control on 95ipm feed....I'm getting lots of dross on the bottom portion, and sometimes smaller cuts fail to cut all the way through the material. The sound of the torch changes wen it does this.

Upping the feed rate to 130 ipm the cut quality improved dramatically, very little dross, everything cut great. Problem was on circles that are about .75" in diameter either the lead in was too short (.15") or the lack of lead out was causing some issue with the circle when the torch stopped (slight deformation of the circle, like a pierce almost.

Upped the feed to 140 ipm and all went to hell....wouldn't cut completely through, lots of dross, etc.

None of the parts are ruined, but getting it dialed in will certainly save me time in finishing everything up. When I see cuts online of 10 and 11 gauge material with no clean up and no dross....I know I'm doing something wrong.

ANY help or pointers to try out would be greatly appreciated!

[Cracker Red]

Just realized that I need to adjust the air pressure to 85psi while the torch is on (It falls to 80-81psi while running).

Also I feel like a dumbass....the unit is in continuous pilot arc mode. I realized that when I was cutting the skeleton up the torch wasn't shutting off.


Not sure if those 2 things would make a difference or not. I'm confused because the more I read people say that a slower speed produces a better cut....but if I'm getting dross at the recommended speeds wouldn't cutting slower end up with more dross?

[dhelfter]

There is both high speed dross and low speed dross. The correct speed produces the best cut! The reason for slower speeds are two fold. One, the slower the speed the more likelyhood the machine will follow the desired cut path exactly. This is not an issue at the speeds you are cutting on our table, as we have very good acceleration. Two, on small features, especially holes slowing down and turning thc off will help eliminate some bevel. I believe this is what people are speaking of as slowing down gets better cuts. Everything is inter related. If you cut below the recommend speed for a given material, voltage will also change, so your standoff will be incorrect.(do to the thc matching you desired volts) I recommend drawing a straight line approx 6-8" long. Generate code per plasma cutter specs, run code with thc off and watch the actual volts reading on the screen. It will bounce at first, but will level off, that is the number you want. Try to make sure the area you are cutting is as flat as possible. The voltage you see will be your ideal voltage.You can then do this cut several times and increase or decrease speed as the dross indicates. You will see the voltage will change. I have found hypertherms specs to be VERY accurate, so if you get something way off I would look for an issue. You should have smaller features such as your circles set up on a different layer, the in sheetcam use the thc off code snippet and decrease the feedrate by 40-50% on that layer. Hopefully Jim Colt will jump in, as he has forgotten more than any of us will know about plasma cutting, but I do believe your 85psi input is low?
Dan
ww.ldrmotionsytems.com

[dhelfter]

Looking at the cut chart 140 is way to fast. 10ga is 95 and 12 ga is 120 so I would set a 11ga tool for around 108IPM. Also make sure you check you z switch offset, using the test bar we provide. This is very important. If you still have issues, please give me a call at either the shop between 8:00am and 5:00pm or my cell after hours.
Thanks
Dan
315-328-4315 shop
315-244-9669 cell

[Cracker Red]

Thanks Dan!

I was screwing with a bunch of settings trying to improve dross.

After "work" I came home tonight, set everything back up per the book (as I've been doing). Checked the Z switch (as I do each time I start the machine up) and made a cut.

I did set the PM85 switch to the correct setting, non-continuous pilot. Also made sure the air was set correctly (indicates 88psi when air is flowing through the torch) and let her rip.

First "new" cut was not bad (none of them have been "bad", but I'm always trying to do better). Had a little top dross but all the drops (I'm cutting 3d dice) fell out. I reduced the speed to 85 (around 20%) and eliminated the top dross, and the bottom got even better.

Responding at 930pm on a holiday is awesome btw....

VERY happy.

[ColoradoWayne]

I'm taking notes - great information here! Thanks guys!

[dhelfter]

Do you have the PM 85 set on auto adjust for the air?
Thanks
Dan

[762frmafr]

I am pretty sure the powermax series of plasma cutters need at LEAST 90psi of inlet pressure with the torch flowing air.

[Cracker Red]

It's a bit of trial and error to adjust the pressure, as the pressure drops slightly when the valve "opens" in the unit (IE - supply 100psi via regulator and when the torch is running the pressure migt drop to 90psi ....but STEADY.

I adjusted it last night when I came home, and overshot the 90psi mark by about 10. I watched a cut and it was pretty good. I noticed that it was reading a bit high, so while the unit was cutting I lowered the pressure to 90 (or really close to).....I could hear a distinct change in how the torch sounded. Wasn't as loud, sounded "smoother".

I think this all steemed from me chasing some settings I'd read about online in effort to get completely dross free cuts.

I'm not there yet, but it's pretty darn good at the moment. Still....I'd like to be able to cut parts 100% dross free like I've seen the master Jim do

[762frmafr]

It's a bit of trial and error to adjust the pressure, as the pressure drops slightly when the valve "opens" in the unit (IE - supply 100psi via regulator and when the torch is running the pressure migt drop to 90psi ....but STEADY.

I adjusted it last night when I came home, and overshot the 90psi mark by about 10. I watched a cut and it was pretty good. I noticed that it was reading a bit high, so while the unit was cutting I lowered the pressure to 90 (or really close to).....I could hear a distinct change in how the torch sounded. Wasn't as loud, sounded "smoother".

I think this all steemed from me chasing some settings I'd read about online in effort to get completely dross free cuts.

I'm not there yet, but it's pretty darn good at the moment. Still....I'd like to be able to cut parts 100% dross free like I've seen the master Jim do

No need to adjust pressure. As long as supply pressure is AT LEAST 90 psi while the torch is flowing air, the machine auto adjusts the cut pressure.

[jimcolt]

There always is confusion regarding air pressure settings on a plasma system. There are two important pressures in every air plasma system:

-Input air pressure.....this is the pressure from your compressed air system. Most plasma cutters specify a range (low to high) that needs to be monitored with a pressure gauge at the inlet (not 10 or more feet away) to the plasma........and with the air flowing through the torch. Monitoring inlet pressure under static (non flowing) conditions and with a remote pressure gauge are useless measurements. The Powermax85 is factory rated to work with an input pressure range of 90 to 135 psi, dynamic (air flowing at the torch), which is within the normal pressure cycle ranges of many air compressors.

-Secondary or cut pressure on most air plasma systems is the actual pressure that goes from the internal pressure control system directly to the torch. On the Powermax85 you can set this pressure manually (with an internally controlled range limited by the power supply electronics), or best....you can set it to "Automatic" control which will automatically set the correct pressure to the torch.....compensating for different torch lead lengths, different consumable sets (and for consumable wear) as well as for different modes (as an example: the pressure for plasma gouging is different than for plasma cutting). I always leave my Powermax85 in "Auto" pressure mode and have no issues with cut quality that may be caused by incorrect pressure.


The Powermax85 (and 65, 105 and 125 systems) all have an electronically controlled "Auto" air pressure control. I always suggest letting the plasma set its own cut pressure.....these pressures were developed by the Hypertherm engineering team and will provide best cut quality and consumable life. Putting the pressure control in manual will allow you to change cut pressure.....and will affect consumable life and cut quality.

So......if you have your own air supply regulator on your air system, and you have a pressure gauge at the inlet of your Powermax85, and you are cutting a long cut with the system set in "Auto" mode......you can adjust your inlet pressure up and down between 90 and 135 psi with no changes in cut quality or consumable life. The internal electronically controlled air pressure regulator will maintain the correct pressure to the torch regardless of your inlet pressure setting, assuming it is within the 90 psi to 135 psi range.

The biggest issues I see with air pressure to the plasma? Relying on a pressure gauge back at the compressor...maybe 20 to 50' away from the plasma. That is not inlet pressure, I guarantee it will be quite different as compared to the pressure at the inlet when air is flowing to the torch.



Jim Colt Hypertherm