TD A120 not cutting thru

[fabguy]

3/4" steel plate, 80A tip with shield, cut chart settings for shield use, clean dry air supply at 85-90 psi. The cutting inches for the part is about 100", it cut 1 part good, went to 2nd part and cut about 3/4 of it then started blowback. Let it set for awhile then tried to start back in the cut but it wont cut thru, had to go over the cut path twice to finally get it cut. Changed out tip, electrode. Started to cut a new part and cut about 1/4 of it then started blowback, I let it keep going then after it got 1/2 way thru it cut thru and finished the rest of the cut just fine. 230v single phase.

[jimcolt]

If you are piercing you need to use the 120 amp process and the proper cut consumables for piercing 3/4". I suspect you are damaging the nozzle (tip) orifice on that thickness. Attached is the cut chart for the A120 when cutting 3/4".

Jim Colt Hypertherm

120 amp steelcut chart, A120.jpg

3/4" steel plate, 80A tip with shield, cut chart settings for shield use, clean dry air supply at 85-90 psi. The cutting inches for the part is about 100", it cut 1 part good, went to 2nd part and cut about 3/4 of it then started blowback. Let it set for awhile then tried to start back in the cut but it wont cut thru, had to go over the cut path twice to finally get it cut. Changed out tip, electrode. Started to cut a new part and cut about 1/4 of it then started blowback, I let it keep going then after it got 1/2 way thru it cut thru and finished the rest of the cut just fine. 230v single phase.

[mlinehan]

Like Jim says, it sounds like you are damaging the tip, probably during the pierce. Check your pierce height and raise it if needed. Also check cut height, although that is a much less likely cause of tip damage.

[fabguy]

I used the 80A tip to try and reduce some of the edge taper, on the lead in I set it to wiggle so the tip would not go bad. I have checked the tips and they are good (no blowout to the sides). I did get the fault at 85psi several times, the book said it could be something internally on the unit, also to check for water in the line, bad ground clamp (which I took apart and cleaned up). I would turn the unit off then turn it back on and the fault would go away, wondering if I should have it looked at.

[Brand X]

The above info is for unshielded 120 amp parts, use the Shielded specs. If you want to go down in amperage, try the 100 amp shielded for 3/4. I am getting book speeds out of my shielded setups, so that is a nice surprise for me. Although it has a somewhat crude amp, and air settings compared to My Esab/and my friends Hypertherm 85 machines. The Thermals sometimes take a bit of work to get right, but they are capable of quality cuts.. What has surprised me most is the nozzle life with the 60 amp consumables. Been cutting quite a lot on one nozzle. Still looks perfect. Not sure if it's the revised pressures over my old SL-100 torch on my 101-151 machines? Anyway, It's just flat out excellent there..

Here is a good deal on some factory 60 amp nozzles/tips.. Cheaper then the China clones,and gets here faster too..
One area the one torch has a real nice advantage. Lots of deals on factory consumables..

http://www.ebay.com/itm/281436448223?ss ... 1423.l2661

[mlinehan]

The 85 code can occur in 2 different modes. If the red status light is blinking really fast (5X/sec), the logic sees the tip touching the plate, either because it actually touches the plate or because molten metal has bridged the distance between plate and tip. If the you can turn the unit off and cut again, that is what you are seeing. Bottom line is, tip is too close to the plate.

If the red status light blinks at 1X/sec, then you might have an internal error, but the unit would likely not recover and cut after you turn it off and on again.

If you use the shielded 100A parts, the shield cap provides better protection against splash and touching the plate and 100A will cut 3/4 very nicely.