Sudden change in cut! please help

[m79b01]

I have been cutting 14ga cold rolled with the finecut tips on a PM65 at 210imp. That seemed to work great. Now if I cut at that speed sometimes it will not cut all the way through. It will pierce, cut then, only cut part way through, then cut again. I, of course tried changing consumables nozzle and electrode, no change. I was forced to slow down to about 165 and now I have terrible dross, but it does cut through all the time. Please help!

[Shane Warnick]

Did you get some more steel? The tolerances for the chemical composition for mild steel vary greatly, could it be that you have some steel with a little higher nickel or silicon content?

Grounded good??

Amps are set correctly?

How does your THC work? Have you reset the arc voltage shift / established a baseline lately?

Moisture. Do you have some moisture in your air system? I know when I was having moisture issues I had the same problem intermittently. Torch would either raise in the middle of the cut due to the resistance change when it was making steam or would pierce and then not cut through as the arc density is crappy when you are making steam.

I would lean towards either an arc density problem due to either a bad ground, making steam (moisture), or the height raising too high and the density is poor at that cut height.

Shane

[m79b01]

Height is good. Steal is the same. Air is good. Seems to only be in one direction though even the sparks only come out towards the Y+ direction. I have checked the torch is level. Could this be another part of the torch? Maybe a pluged air passage?

[tnbndr]

I would either change out all the torch parts or one by one till the problem is gone. You've already done electrode and nozzle, follow with swirl ring, shield and finally retaining cap. My guess is it is the swirl ring or some of the ports are plugged in the shield.

[m79b01]

follow with swirl ring, shield and finally retaining cap. My guess is it is the swirl ring or some of the ports are plugged in the shield.

That was my thoughts too. I am going to try today.

[jimcolt]

The two things that I hear every day from users that cause the finecut consumables not to cut all the way through the material are related to height and air flow or air quality. You say your air is good.....and your height is good (how did you check them?).

Height has to be at the physical height listed in the operators manual for the powermax.....don't go by the arc voltage setting as there are a few variable that can alter the voltage/height relationship. Adjust the arc voltage until the height is correct.

Air pressure and flow are controlled by the:
-incoming air pressure when air is flowing at the torch. When flowing, the incoming air must be between 90 and 135 psi.
-The retaining cap has internal passages that split air flow between the nozzle (there is no part called a "tip") and the shield. Over time these passages wear or get plugged. Try a new retaining cap.
-The swirl ring wears over time...it controls the flowrate and the swirl pattern of the plasma gas flow. A worn swirl ring can cause misfiring and low cutting power.
-Electrode and nozzle.....these are critical, make sure they are genuine Hypertherm parts.
-Make sure the torch oring is in good shape and has a small amount of silicone oring lube. A small leake at the oring will cause low cutting power.

Jim Colt Hypertherm

Height is good. Steal is the same. Air is good. Seems to only be in one direction though even the sparks only come out towards the Y+ direction. I have checked the torch is level. Could this be another part of the torch? Maybe a pluged air passage?

[m79b01]

Thanks for the explination Jim.

My height is .060 and I have tried with and without the height control.
I even tried taking the Powermax off the "auto air setting" and turned it all the way up to 81psi. Inlet is 120psi.
All consumables are genuine.

I think the direction of the spark means something and I will be checking these:

-The retaining cap has internal passages that split air flow between the nozzle (there is no part called a "tip") and the shield. Over time these passages wear or get plugged. Try a new retaining cap.
-The swirl ring wears over time...it controls the flowrate and the swirl pattern of the plasma gas flow. A worn swirl ring can cause misfiring and low cutting power.

-Make sure the torch oring is in good shape and has a small amount of silicone oring lube. A small leake at the oring will cause low cutting power.

I would not have thought about that one and I will be checking that.

[m79b01]

What a morning....

I replaced the swirl ring, shield, nozzle, and electrode. Inspected and cleaned everything else. Tried to cut some small pieces and it was not much better. Set up to run a test cut THC off and wow the cut was great. So, I ran some more test cuts and all looked good except the voltage. I have always been close to book values. So I expected about 82 volts for the 14 ga at .060 but I was getting 64. WTF! So I tried standard 45a consumables with similar results. (book value 134 cutting at 119) Now what? After discussion with Hypertherm, it looked like I was going to be trying to open the case and read raw volts etc..... One more look at the consumables (which are all new) and a few test cuts and now it is working how it should. I must have not had something tight enough i.e. swirl ring.

I will try cutting some parts tomorrow and repost if I have any more issues.

In summary Thank You all for your help. And I will remember to change ALL the consumables first thing next time.

Sometimes I am my own worst enemy!

[vmax549]

Chances are good that your voltage reading problem is in the Candcnc unit. Had the same problem here. It finally took replacing the modual that reads the cut voltage to fix the problem.

OR just reset all your cut voltage values by the same percent of difference and cut on. that works as well (;-).

(;-) TP