PMX 85 cutting quality

[Geanvert]

I will share photos to show you my problem with cutting on 16 mm thick soft steel. The result is not at all satisfactory, does anyone among you get excellent results with their PMX85 on the same thickness?

[Geanvert]

sorry, I don't have any pictures, these are videos. I'll start again tomorrow.

[Geanvert]

finally I took screenshots so as not to wait.

[Geanvert]

85A at different speeds. 25% of the initial speed of 550 millimeters / minute

[weldguy]

Have you measured your cutting height by pausing the machine and checking with feeler gauges?

Are you using an auto height control system?

Approx how big is that ring you are cutting?

[Geanvert]

I did not measure the height when making the break, I do not have any thc either, and the round holes like the squares are 16 mm in diameter or on the side. When I make holes of 24 mm in diameter in the same thickness, they are slightly conical. 16 mm is not very thick, I soon have 20 mm to cut, I am not very confident.

[adbuch]

I would check to make sure you are cutting the correct height. You can use the Hypertherm book values for pierce height, cut height, pierce delay, cutting speed, and current setting. Also make sure you have the correct matched set of consumables including nozzle, electrode, swirl ring, shield, and cap. Check to make sure you have sufficient air supply. It is best to have an air pressure gauge installed right at the air entrance to the plasma cutter and with a reading of around 100psi with air flowing thru the torch. Also check for moisture and/or oil contamination in your air supply.

I always connect my work lead directly to the material I am cutting. I use a Hypertherm Powermax 85 and 45xp.

David

[Geanvert]

I'll look at as many things as possible, but with your equipment, what quality do you get on 15 or 20mm thick mild steel material? Do you have any pictures to share?

[adbuch]

I have not cut any thick material lately, so I have no pictures to share. But with the correct settings, air pressure, etc. you should be able to get some nice straight cuts.
David

[adbuch]

Here is the Hypertherm page showing some sample cuts.

https://www.hypertherm.com/resources/mo ... t-quality/

[adbuch]

Here is a sample I cut a few months ago. This is a "drop" from a hole I cut in some 9mm thick mild hot rolled steel.
I cut at book specs. The inside of the hole looked better with less taper due to the direction of cut using the proper swirl ring.

David

[adbuch]

Here is the inside of the center hole. This has less taper than the outside shown in the previous photo.

David

[jteller07@hotmail.com]

Looks like you have a water table so derate cut speed from the 870mm/min by 20% to 653 mm/min. If you have a cut speed 2 do 60% of the new cut speed 1 so 392 mm/min. Change your leads for the squares or drop the speed as it reaches the lead-in and burn past is a short bit to clean up the extrusion. To clean up the half circles put loops on either side so that the arc is able to stabilize. As others have said make sure cut height is correct before starting the cut. If you want to check your air pressure do the below and hold down the two buttons with blue arrows to get into the service screen.

[weldguy]

Cut height is very critical to edge squareness, see this topic here https://www.plasmaspider.com/viewtopic.php?t=30283

Also cut direction for internal and external profiles is critical to edge squareness, see this topic here https://www.plasmaspider.com/viewtopic.php?t=30272

To see more great topics like this that may help check them all out here https://www.plasmaspider.com/viewforum.php?f=202

I know you can dramatically improve on the cuts shown in your picture, will take some time and testing.

[Geanvert]

Hello, here I am again. Many thanks for all the information given. Especially the one where you can access the plasma menu. Something I absolutely did not suspect and which allowed me to see directly that I have a working pressure of 68psi while it is set to 78psi on the display. So the first thing that causes problems with the cutting quality on a thickness greater than 10mm. I am looking to modify my air supply pipe diameter because I have 150psi in the compressor tank. I am far from it and a tube that is not very big. Now I understand much better why I have problems in certain circumstances with my impact wrench outside with an even longer pipe.

[adbuch]

Happy to hear you are making progress. Keep us posted as you get your system dialed in for those top quality cuts you are after.

David

[Geanvert]

Hello, I have my air inlet which is solved. After several tests, at the basic speed of 550mm/min but reduced by 45/40/35 and 30% for the holes. Here is the result, 30% would be the right compromise for a result that could be admissible according to the photo of the hole alone.

[Geanvert]

so the photo of the display where we can clearly see the pressure which is perfect, it was a test at 65A but the photos of the result are carried out at 85A in 16mm thickness.

[weldguy]

Looks better and if I understand correctly you said 30% of Hypertherm suggested cut speed produced the best results?

Did you get a chance to check the cut height and cut direction?

[Geanvert]

hole Ø 16mm, notch 7x6mm
the direction is good, it's automatic for the interior contours. the height, I don't know how to do it because as soon as I stop working voluntarily, the torch goes up automatically. or else you would have to go into the machine settings to say not to go up. on the other hand no it's not hypertherm who recommends 30%, it's me who noted the result of the 4 tests at different speeds for very small surface areas. but it is obvious that we will not have a result like a laser. I mentioned the dimensions if by chance someone who has excellent results with similar equipment would be willing to test and post photos to compare.

[Geanvert]

yes it is indeed 30% of the speed of 550mm/min recommended by hypertherm which gives the best results, but the holes remain conical despite everything. I have not tried to go even slower. I could imagine that the ideal would perhaps be 105 A for this thickness and 125A for 20mm thickness

[weldguy]

If 30% of the suggested speed is working for you I don;t see a problem with that, Yes won't get anywhere near a laser cut but I am sure you can still improve.

If your taper is in the same direction (towards the center creating a cone look) around the entire profile (hard to tell from the picture) than you should be able to improve upon it with cut height adjustments. If your taper is not creating a cone look but tapering to say the left on both sides you likely have a worn out nozzle where the hole is no longer round.

I realize now your machine lifts the torch and you can't measure but you can still look at the finished cut and determine whether to go up or down with the cut height to reduce taper angle. I would suspect you need to go down so I would do test cuts and reduce the cut height by .010" with each test cut and see how things go.

This image from a topic I previously directed you to shows the effects of cut height and the type of taper it will produce based on the height.

[SegoMan DeSigns]

When was the last time you inspected all of the o-rings?

Here is a thread on them:

https://www.plasmaspider.com/viewtopic. ... gs#p224708

[Geanvert]

personally never, it's a machine that I've had for a year and I do very little cutting with it. I'm a farmer, so not a metal craftsman!!!! but in any case, I would have liked to see the work with the same design at someone who has an installation with equal power and who is very efficient on his cutting quality to see how he gets on.

[weldguy]

personally never, it's a machine that I've had for a year and I do very little cutting with it. I'm a farmer, so not a metal craftsman!!!! but in any case, I would have liked to see the work with the same design at someone who has an installation with equal power and who is very efficient on his cutting quality to see how he gets on.

I can assure you, some here could get better results that what you are seeing. Achieving this can be difficult for someone who doesn't do this every day and not "in tune" with his/her equipment. I highly suggest taking my advice above, inspecting your taper, determining if it is torch height or worn consumables, make the changes and complete test cuts while monitoring the taper and making height adjustments accordingly.