Bad cuts at high speed on 16 ga?

[ferometal]

Been playing around with the new table, and trying various metals. Tried some simple 16ga steel today and the cut charts for the Hypertherm 65 show:
45 amp,
torch to work 0.02,
pierce height 0.08,
pierce delay 0.1s
voltage 130
best cut travel 350ipm,

Plasma set at 45 amps with correct gas pressure, didn't have the finecut so just used the 45 amps.

I thought 350ipm seemed way too fast so I tried it around 225ipm, and the program just rounded the corners and it was junk. Slowed it down to 175 ipm and it got better.

Not sure if its a matter of playing with the plasma settings to get better results, or if the Dynatorch system just can't follow the path close enough at those speeds.

Anyone have any comments or decent settings for 16ga mild steel? Attached are some pics of the 175ipm cutting, I'd like to do better if I can.
Thanks everyone.

[jimcolt]

I'm guessing that you either have a Hypertherm Powermax65 or Powermax85 system. Also....you have listed the cut height below as .02"...it should be .06". Another point....and I have seen this issue with Dynatorch height controls before...use the Hypertherm recommended voltage setting just as a starting point...and adjust the arc voltage so that the torch standoff stays at .06" durring the cut. Do not worry if the arc voltage readout is wayy off the 130 volts in order to maintain .06"...the physical height is most important.

Most cutting machines have a hard time maintaining speeds above about 150 inches per minute, especially when there is a lot of detail in the cuts. This causes the machine to be in accel and decell modes most of the time, so effectively is doing the cutting at speeds considerably slower than you want to be cutting at. Plasma produces dross (called low speed dross) when it is cutting too slow.

If you have a 65 or 85 plasma...bst bet is to use the FineCut consumables, follow the specs and adjust height as suggested above. The FineCuts allow you to use slower speeds. You also can simply use lower amperage with the 45 amp nozzle....I have been successful with that nozzle at 30 to 35 amps on 16 gauge....I woul experiment with speed, maybe start at around 120 and keep increasing until dross goes away...once again, maintain the physical cut height. Everytime you change speed you may have to tweak the arc voltage to keep it at .06" off the plate.

Hope this helps...let me know your results!

Jim Colt Hypertherm

Been playing around with the new table, and trying various metals. Tried some simple 16ga steel today and the cut charts for the Hypertherm 65 show:
45 amp,
torch to work 0.02,
pierce height 0.08,
pierce delay 0.1s
voltage 130
best cut travel 350ipm,

Plasma set at 45 amps with correct gas pressure, didn't have the finecut so just used the 45 amps.

I thought 350ipm seemed way too fast so I tried it around 225ipm, and the program just rounded the corners and it was junk. Slowed it down to 175 ipm and it got better.

Not sure if its a matter of playing with the plasma settings to get better results, or if the Dynatorch system just can't follow the path close enough at those speeds.

Anyone have any comments or decent settings for 16ga mild steel? Attached are some pics of the 175ipm cutting, I'd like to do better if I can.
Thanks everyone.

[ferometal]

Thanks Jim, the 220948 shielded caps for the fine cut just came in yesterday night, so I will try it today with your settings.

Quick question regarding torch to work distance: is the 0.06 the distance from the shield to the work, or from the nozzle to the work?

I'm more familiar with welding terminology, ESO and stickout, but those both refer to the distance from the contact tip to the workpiece, regardless of where the nozzle is set. Is this the same for plasma? Its tough to estimate the amount of recess in the shield, but the fine cuts don't have much recess at all.

Thanks Jim!