1250 torch cutting at an angle

[Beefy]

Has anybody ever come across this one.

My cuts have some terrible angle on them, not bevel but more like the torch is mounted at an angle in its holder.

It's a Powermax 1250 hand torch and I've taken all measures to ensure the torch head is perpendicular to the table. In any case the angle I'm getting is very obvious so if it was due to the torch head being tilted it would be quite obvious too.

I put a new 60 amp nozzle in before the last cut. Is it possible to have the plasma jet coming out at an angle when the torch is square.

Thanks, Keith.

[jimcolt]

Here are issues that can cause severely beveled cuts with a plasma torch:

1. Torch not perpendicular to the plate.
2. Incorrect combination of consumable parts (refer to the operators manual)
3. Damaged shield or nozzle. center orifice of these consumables needs to be perfectly round....with no nicks. Damage is ussually caused by pierce too thick...or too close to the material being cut. Refer to the detailed cut paramter charts in the operators manual.
4. Incorrect air pressure or moisture/oil in the air system.
5. Incorrect pierce height and/or cut height.
6. Damaged or worn torch retaining cap, swirl ring or torch body.


If you can provide more details on how you are cutting (hand cutting? Machine cutting?) and what equipment you are using (CNC machine? Height control?) as well as the material thickness and power level (amperage) I can steer you in the right direction. Pictures of the cuts, the used nozzle (closeup of orifice) and description of the bevel (is it uniform around the cut or does it vary from positive to negative angularity around the cut?) will help as well.

Jim Colt Hypertherm

[Beefy]

Hi Jim,

thanks very much for the response.

I'll have to spend some time eliminating each of the six possible causes you mentioned.

It's a Powermax 1250 hand torch being used on my cnc table (Candcnc with digital torch height control and mechanical touch off for initial height sensing).

The slanting cut is pointing in one direction all the time. The bottom of the cut is angled towards the top left corner of the table. To further clarify this, if the cut direction was towards the top left corner then the cut would be fairly straight but if the cut turned 90 degrees then you'd have the bottom of the cut angled towards the top left corner. It's as though the nozzle is not perpendicular to the table yet it looks very square to the table surface. It's not the typical issue of flare in the cut. Assume for this case the sides of the cut are parallel but sloping in the said direction. This particular cut was on 10 mm steel using brand new 60A nozzle and shield. The electrode had very little wear of the hafnium.

I'll have to go into this problem in more detail so I can gather as much information as possible. I'll go over everything you told me to check then I'll have a play with the torch, rotating the consumables inside, turning the torch around to see if the angle turns around with it. I'll remove the torch and do a manual cut to view the plasma jet and see if I can visually see it coming out of the torch at an angle. I'll also try different size consumeables (I think I may also have a new swirl ring).

The cut was a few holes done at 60% feed rate and THC turned off, then the THC turned back on and the feedrate done at the recommended speed for the rest of the cut. The slant was the same in both cases.

I do have an unrelated question Jim. Is it possible to reduce the period of the post air flow after the arc has extinguished. It's quite long, maybe 10 seconds and my torch is trying to touch off with air blasting out the nozzle. I have a counteract spring on my floating z-axis so it doesn't take much to lift it up (good for thinner metals which can push down on touch off) and I'd be surprised if 80 or 90 psi of air blast isn't stopping the torch tip from touching the metal (acting like a hovercraft if you know what I mean).

Cheers,

Keith.

[jimcolt]

Good luck with your troubleshooting of the cut angularity issue. I'll be happy to continue working with you on this.

The post flow is carefully engineered by Hypertherm process engineers in order to provide adequate torch cooling as well as consumable cooling. It is not adustable.....as we shorter consumable life and possible torch damage if the cooling period was shorter. The actual orifice pressure at the nozzle is around 30 psi.....however it is enough to deflect thin materials. All of our torches under 100 amps are gas cooled, our torches over 100 amps are liquid cooled and do not have a post flow.


Jim Colt

Originally Posted by Beefy Hi Jim, thanks very much for the response. I'll have to spend some time eliminating each of the six possible causes you mentioned. It's a Powermax 1250 hand torch being used on my cnc table (Candcnc with digital torch height control and mechanical touch off for initial height sensing). The slanting cut is pointing in one direction all the time. The bottom of the cut is angled towards the top left corner of the table. To further clarify this, if the cut direction was towards the top left corner then the cut would be fairly straight but if the cut turned 90 degrees then you'd have the bottom of the cut angled towards the top left corner. It's as though the nozzle is not perpendicular to the table yet it looks very square to the table surface. It's not the typical issue of flare in the cut. Assume for this case the sides of the cut are parallel but sloping in the said direction. This particular cut was on 10 mm steel using brand new 60A nozzle and shield. The electrode had very little wear of the hafnium. I'll have to go into this problem in more detail so I can gather as much information as possible. I'll go over everything you told me to check then I'll have a play with the torch, rotating the consumables inside, turning the torch around to see if the angle turns around with it. I'll remove the torch and do a manual cut to view the plasma jet and see if I can visually see it coming out of the torch at an angle. I'll also try different size consumeables (I think I may also have a new swirl ring). The cut was a few holes done at 60% feed rate and THC turned off, then the THC turned back on and the feedrate done at the recommended speed for the rest of the cut. The slant was the same in both cases. I do have an unrelated question Jim. Is it possible to reduce the period of the post air flow after the arc has extinguished. It's quite long, maybe 10 seconds and my torch is trying to touch off with air blasting out the nozzle. I have a counteract spring on my floating z-axis so it doesn't take much to lift it up (good for thinner metals which can push down on touch off) and I'd be surprised if 80 or 90 psi of air blast isn't stopping the torch tip from touching the metal (acting like a hovercraft if you know what I mean). Cheers, Keith.

[patclick]

Keith,

I had the same problem on a XL 150 plus. I replaced the torch head because of a coolant lead. When I did, I noticed that some of the air holes around the outside of the head were plugged and damaged on one side. It is cutting straight now with the new head. You might try using a cutting torch tip cleaner to clean these holes and see if that helps.

Pat

[Stout]

I had a very similar issue a few weeks ago with my T80M. After just a few pierces there was a severely angled edge on one side. And nozzles were not lasting very long. The electrode seemed to be burning off center. I was really worried.

I called Hypertherm support and the tech immediately asked when was the last time i had changed the swirl ring. I said never because it's a part that does not wear out. Well, that was the problem. The little holes in the swirl ring seem to collect some type of debris. You have to look really close to see it. They were collecting the gunk on one side causing the swirl of air to be off enough to cause a problem. New plastic baffle installed and it cuts like a dream again.

I don't understand where the gunk is coming from as I have a water/oil trap and then a paper roll filter in front of the PM1250 which has it's own water trap.

I had begun to look at a Duramax torch upgrade thinking I had a bad torch or something. I'm so happy with tech support and the $10 fix.

[adscnc]

Originally Posted by jimcolt Here are issues that can cause severely beveled cuts with a plasma torch: 1. Torch not perpendicular to the plate. 2. Incorrect combination of consumable parts (refer to the operators manual) 3. Damaged shield or nozzle. center orifice of these consumables needs to be perfectly round....with no nicks. Damage is ussually caused by pierce too thick...or too close to the material being cut. Refer to the detailed cut paramter charts in the operators manual. 4. Incorrect air pressure or moisture/oil in the air system. 5. Incorrect pierce height and/or cut height. 6. Damaged or worn torch retaining cap, swirl ring or torch body. If you can provide more details on how you are cutting (hand cutting? Machine cutting?) and what equipment you are using (CNC machine? Height control?) as well as the material thickness and power level (amperage) I can steer you in the right direction. Pictures of the cuts, the used nozzle (closeup of orifice) and description of the bevel (is it uniform around the cut or does it vary from positive to negative angularity around the cut?) will help as well. Jim Colt Hypertherm

Hello Jim
Having a taper problem cutting 13mm mild steel. Using 1650 with duramax torch.85 amp consumables.set at 85 amp. Torch seems square. New consumables, apart from swirl ring. Using CandCNc control on a 8x4 table. 2 parallel sides are tapered severly in line with the x axis(short axis). Only 1 side pretty good . Piercing at 4.5 cutting at 1.5 off plate. If I turn the torch through 90 degrees the problems the same indicating it's a table problem, but the torch is much squarer than the bevel produced.
Any thoughts on this.?

[jimcolt]

An air plasma torch, especially when cutting at full output power on materials that can also be cut at lower power levels, will produce a taper. I would bet that the taper on 13mm (1/2") will be somewhere in 3 to 5 degree angularity range (out of 90 degrees). So...if the torch was slightly tipped in its holder (say it was off square by 3 to 5 degrees in comparison to the plate).....then one side of the cut could have a 6 to 10 degree taper, while the opposite side could have a 0 degree taper. So...it is very important to have the torch perfectly square to the plate when plasma cutting....and squaring the torch is best done with a square (not a level) and with the use of a straight bodied machine torch....so you have a good long surface to measure from.

The fact that you rotated the torch in its holder...and the angularity issue stayed in the same position on the plate...indicates that the angularity variation around the part is related to torch mounting. Varying angularity could also be caused by different speeds or different torch heights in each axis direction as well.

If the angularity was caused by a damaged consumable, incorrect gas flow, or other issues within the torch...then the angle would have followed the torch when it was rotated in its holder.

My suggestions:

1. Go back to the machine and carefully square the torch to the plate to be cut.
2. Use the lowest powered consumables for the materials thickness you are cutting. Since it is a Hyperthem system, follow the mechanized cut charts using optimum or "best quality" cut speeds exactly as listed in the manual. Use the correct pierce height, pierce delay, and cut heights for the material as well. For 13mm plate.....I would suggest using the 65 Amp shielded consumables for the best cut edge squareness.

Jim Colt