Chewing Consumables and Unreliable Piercing etc

[Wattagan]

Hi all,
Like many people I'm posting here because I'm desparate

This machine eats nozzles and electrodes, randomly fails to pierce and mostly cuts crooked.
Sometimes tips only last a few minutes of cutting. Sometimes all day ???
Since new it has been always pretty much this way. Sometimes it's not too bad but other times almost unusable.

Better outline the basics before I go on :-
I notice most posters here are American but I am in Australia using a Chinese made machine called a JCUT.

Very nice and well made using a Panasonic P80 torch with 100Amp power supply.
Software is Microstep SH-2012AH-QG (pretty clunky but works) with torch height controller SH-HC30 using contact ignition.

I am cutting mostly 3mm High Tensile Gal steel sheet at 40Amps and 1300 speed (in Microstep terms) with 95psi air and torch height controlled to 250Volts which results in about 4mm cutting height.
I have recently added 3 extra air filters stepping down to 0.01 micron all with water traps in the belief that water was the culprit but it doesn't seem to have made any difference

Following image is of an electrode and nozzle (1.1mm) after removal.

See the burn mark on the nozzle is off centre. They all burn out like this after a small time and then the flame generated is crooked as it comes out of the nozzle and so does not cut straight down but at an angle resulting in a cut which slopes to one side as shown below on a bit of 1/4" steel so it's noticable.

This angled cut means bottom dross on one side of the cut and some top dross on the other side.
But obviously the main problem is the electrode damage causing this crooked cut and of course ultimately the electrode/nozzle fails.

Next picture is of what was supposed to be a set of plates with holes but due to pierce failures turned out like shown

The red arrow shows one of the places it failed to pierce.
When this happens the torch raises to about double working height and a sort of Arc Bubble glows beneath it just burning the metal a bit but not cutting.
If I pause and back it up and retry the hole sometimes it will pierce on the second try or the third so the problem is not permanent however once it starts happening the chance of getting a good pierce has gone and there is not much point continuing.
Changing the electrode and nozzle usually fix it but only for a short time.

The next picture is a series of test holes

The two that did cut out completely were done with a 10mm lead in from the inside giving the poor piercing time to get a cut going before actually starting on the hole itself.
The others had only 5mm lead in and as you see in the two middle ones by the time the circle was complete it had not met up with the start because the start had not started cutting till 10mm after it should have.

It's winter here and the steel is cold and someone did suggest warming it up ?
But we had this problem in summer too !

Air pressure is easily maintained during cutting and the pressure gauge does not drop during cutting.

Beats me !!

[muzza]

Hi and welcome wattagan, I too am an Aussie and understand the problems we can have dealing with the other side of the world due to distance and time frame.

I am not familiar with your machine, software or settings you quote (microsteps doesn't relate to distance without other parameters) but will try and relate it back to what I am more familiar with. Your machine is Chinese, I assume you have tried to get answers from the manufacturer. Like I said I'm not familiar with your machine but past experiences have shown me that the Chinese are very good at making things look very good but in their process of copying miss the finer details, a classic example is the knock off Hypertherm consumables, visually look the same but only last a fraction of the time and deliver poor cut quality.

Your cutting 3mm galv at 40 amps, I don't know what your speed means but on my PM45 I'd normally cut that at about 4000mm per minute at 40 amps and with galv have a totally dross free cut. Pierce height would be 3.8mm and cut height would be 1.5mm. You say your cut height is 4mm, this seems way too high to me.

You have added filters, good move as air quality is often overlooked but each filter will reduce air volume and pressure. Have yo checked your pressure at the cutter with air flowing?

The burn mark on your nozzle being offset like that, is that how they always look? If so I'd suggest that maybe an alignment issue may be present within the torch itself , as I said above I'm not familiar with the Panasonic torch so don't know whether something can get damaged or bent (again as it's a Chinese set up don't assume that just because it may be branded Panasonic that it actually is) If your plasma arc is not straight, your cut can't be.

In the plates you have shown with the holes I'm a little confused with the accompanying text. You say you have a 10mm (and 5mm) lead in yet I can't see the lead in. Normally you have a lead in where the torch will come down and determine material presence and height and by using ohmic or touch off sense the height, raise to pierce height, pierce and remaine stationary for the preset pierce delay and then start cutting on this lead in to the actual cut path and then do the cut and continue to any lead out if set or stop at the end of cut for any pause at end of cut and then move on to the next cut and repeat the process. It appears that with what you have shown that yours is trying to pierce on the fly. If it is, I can't see this being very consistent especially as your acceleration will change on straight as opposed to corners etc. and on heavier material it just wont get a chance to pierce at all.

Seasonal temperature changes in you material I wouldn't think would make a difference, it's only a fraction of a percent in the context of the actual cutting temperature but the moisture we have in the atmosphere at present sees me draining my compressor two or three times a day lately (Victoria) where as in summer there is hardly any water in the tank.

Air pressure, again have you checked this at the cutter with the air flowing in the torch?.

I hope I have been of some assistance, sorry I can't help more.

Murray

[Wattagan]

Thanks Murray,
You said "Your machine is Chinese, I assume you have tried to get answers from the manufacturer. "

Despite the stigma of things Chinese I have found this manufacturer very good and eager to help.
However they only Make the machines. They buy the software from someone else and the torch similarly I suppose.
So they can't help much with cutting issues. But I can't fault the work they have done themselves.

"Your cutting 3mm galv at 40 amps, I don't know what your speed means but on my PM45 I'd normally cut that at about 4000mm per minute at 40 amps and with galv have a totally dross free cut. Pierce height would be 3.8mm and cut height would be 1.5mm. You say your cut height is 4mm, this seems way too high to me.
"

I don't know what the speed 1300 relates to but from trial and error it gives the best results, any faster risks not cutting and slower creates more dross.
When the flame is straight (not much of the time) it does cut pretty well dross free. All we get is on one side of the cut due to the flame being angled.
Pierce height for this is zero because it uses contact ignition and the cutting height controller adjusts the height to maintain a set Voltage in the supply. Too high and voltage required to maintain the arc rises so the torch lowers to maintain the voltage. Works well and I don't think that's the problem.

The problems are I think 2
1/. The flame is crooked most of the time
2/. Piercing is randomly effective
Once a cut is established there are generally no problems at all until it ends.
Except that the cut is not vertical
It's just that you never know each time it starts a hole or line whether it's going to make a clean pierce or not.

"Have yo checked your pressure at the cutter with air flowing?"

Air flow at the tip is good even with the nozzle removed and no restriction.
During testing this the line pressure does not drop more than 5psi
In any case the problem is when Piercing and at that time the air has had time to build up to full pressure before the pierce.
If there was a supply problem it would show up worst during a long line cut which is no problem.

"I'd suggest that maybe an alignment issue may be present within the torch itself"

Yes I am thinking that way myself.
I think I will get them to send me a new torch just to see.
As for consumables I have not been able to find them in Aus but have used ones from China and USA and UK with no differences. Same problem.

"You say you have a 10mm (and 5mm) lead in yet I can't see the lead in. "

Yes in those tests I set the lead in and lead out to come from the Inside of the circle so you would see them on the disk that has been cut out.
In the two that worked with the 10mm lead ins (or lead outs if you think of them that way) it cut cleanly because despite the bad piercing it had time to establish it's flame before getting into the circumfrence of the circle.
With the 5mm ones you can still see the blanks in place with the burn marks of the piercing inside of the circle.

I would like to maybe change to a more common supported torch but although it's only connected by one wire and an air hose it seems that all the others have some sort of torch specific requirements from the software or power source.
No one I have come across seems to have experience with swapping torches.

Thanks for the thoughts anyhow.
I will get them to send a new torch in the hope it's misaligned inside.

[beefy]

Hi Wattagan,

did the table come with any PDF manuals you could attach here. My experience with Chinese machinery is the manufacturers must think anyone is crazy for wanting that. When they do supply it, it's a bonus when it's readable. Do you have:

Manuals for the software / controller
Electrical connections diagrams so you know how everything is connected together
Plasma cutter manual, with diagrams showing where a cnc controller interfaces with it (torch on signal, arc OK signal, volts feedback). Cut parameters for different thicknesses/types of metal.

Keith.

[vmax549]

Can you adjust the Pierce delay time either through the machine or Gcode ?

Looks like you need to give it TIME to complete the pierce BEFORE axis movement begins.

If you do not acheive a clean pierce the splashback of molten material will damage your tip and the plasma will cut a new path of exit off to one side of the tip.

Just a thought, (;-)

[I Lean]

With the contact start plasma, I don't think you'll ever get any good consumable life out of it. The fastest way to kill a nozzle is to pierce too close to the plate, so the molten metal "splashes" back onto (or into) the nozzle and screw it up. Since your machine requires it to touch the plate to establish the arc, you're automatically too close no matter what you do.

Are you locked into having to use the Panasonic plasma, or can you retrofit a real machine on there? By which I mean Hypertherm, naturally. As long as you can set the parameters to match what Hypertherm specs (as muzza detailed already), you'll be amazed at the consumable life and cut quality.

[Stout]

With the contact start plasma, I don't think you'll ever get any good consumable life out of it.

This.

I did a very short search on the torch and it seems to support non-contact start. If there is a setting on the machine to change it to pilot arc start, you should make that change first.

[muzza]

You might be able to get your consumables from these guys, Steve contacted me a while back saying that they had a large range of non genuine plasma and welding consumable but I will only use genuine Hypertherm. They may have your ones or may be able to help you with a retro fit torch or other solution. http://tridentequipment.com.au/
Murray