Powermax 65 pulsing arc and noise

[rwskinner]

I've been cutting some 304L 16 ga stainless and my PM65 seems to be pulsing. I can see the arc pulsing while it's cutting and I can hear it as well. The actual cut looks good with no dross, but has a slight saw pattern about every 1/4". To describe it, its a nice straight line, but the pattern on the edge looks saw cut almost with a course feed, which I'm sure is being caused by the pulse. You can't really feel it much but it's there, and just plain doesn't sound right.

I'm set at 45 amps, using the fine cut components. 0.080 Peirce, 0.020" Cut Height, and 240 IPM and my voltage is runnin 72-73 volts.
All the consumables are brand new. I tried on 16ga mild steel and it did not do this.

Is this a characteristic of stainless?

[rwskinner]

Correction, I just tested it on clean 16 ga mild steel using book specs for Slow Speed Fine Cut and it did the same thing.
I can't see the DTHC bobbing any but I will turn it off and do some cuts and see if it goes away.

Richard

[tnbndr]

I don't have a PM65 but make sure your cutting in the plasma mode and not perforated or gouging mode. My PM45 has a switch on the front to select and this has gotten changed by mistake and it makes it cut weird.

[abmetal]

Shortly after we got our PM65, it would start pulsing, sounded like a steam train chugging. It didn't do it all the time but since it was still under warranty Airgas contacted Hypertherm and they said something on the circuit board was bad so they sent us a new one.

Allen

[jimcolt]

It is always best to change consumables as a first resort....including the shield, retaining cap, the swirl ring and nozzle and electrode just as a precaution....be sure you have the mode switch in the cut position and the amperage set correctly and air flow in Auto mode. If the pulsing persists...it is time to contact Hypertherm technical service. technical.service@hypertherm.com or 800 643 9878 Jim Colt Hypertherm

Correction, I just tested it on clean 16 ga mild steel using book specs for Slow Speed Fine Cut and it did the same thing.
I can't see the DTHC bobbing any but I will turn it off and do some cuts and see if it goes away.

Richard

[rwskinner]

I took the DTHC IV out of the picture and it did perfect, so upon investigating, the DTHC IV control was set to Fast Acting, but the G-Code had it set to Slow Acting. The G-Code did not over-ride the setting like it should so it was jumping up and down trying to maintain the setting. Which is odd, because on Slow it maintained the voltage perfectly.

Problem solved.

RIchard

[jimcolt]

Rough motion and / or an oscillating z axis often will cause the "pulsing" issue with any plasma. I did not suggest you look at that because in your second post you said "I can't see the DTHC bobbing any but I will turn it off and do some cuts and see if it goes away".

A good test is to simply put your hand on the torch while it is cutting.....you can easily feel rough motion or oscillation by doing this....both of which will leave striations in the cut edge. Glad you got it figured out! Jim Colt Hypertherm

[rwskinner]

Jim, while I have your ear. I powered my PM65 on the other day and it had a 0-99 on the display. I cycled the power and it has been fine since. It only appeared that once, and honestly, it felt like the power switch on the back wasn't "clicked" in all the way. Could that have been a fluke and nothing to worry about unless it comes back or should I be proactive on it?