Optimizing Cut Quality

Plasma Cutters
1

I’ve calibrated my Plasma Cutter using test programs adapted from Test cut program to find the ideal cutting speed but these were all done with the only nozzle (1.0) I had for my Plasma Cutter. I’ve received some new nozzles of assorted sizes and I’d like to calibrate these as well.
My weak (and possibly wrong) understanding of the relationship of cutting parameters are:

  1. Air pressure is determined largely by the nozzle size, the larger the size, the more air pressure is needed.
  2. Cutting a particular material is determined by Amps & Cutting speed where Speed needs to increase as Amps goes up and conversely Speed needs to be dropped if Amps are lowered.
  3. Nozzles of a particular size are rated for a particular Amp Range, eg, 0.6mm 20A, 0.8 30A, 0.9 40A, 1.0 50A, 1.1 60A.

Now, given this view of the plasma cutting world, I conclude that my tests cutting thinner gauge material, where my current was below 40-50A, should be redone, at the very least, with a nozzle that is designed to operate at the lower currents. However, I’m curious how cut quality will be affected if I go to even lower currents (now that I have smaller nozzles that are designed for the lower currents) and drop the speed appropriately. In other words, if I can cut 16ga steel with 35A and my oversized nozzle, can I cut 16ga Steel with my 0.8 or even 0.6 nozzle if I cut at a slower rate? And, if I can, what will yield the optimum cut quality?

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2

TomWS, have you recalibrated based on various nozzle sizes and other parameters ? Have your results verified your understanding as posted above ? If so, which plasma cutter and torch do you recommend for CrossFire Pro that supports that range of nozzles and parameters ? Thanks.

3

I’ve recalibrated my setup and I do use smaller diameter nozzles when cutting thinner material, especially mild steel, which, IMO, is the friendliest material for plasma cutting. You can go really small in this case. I’ve found aluminum is tricky because it only melts, it doesn’t react to the plasma like steel does and it sinks the heat away faster so the smaller nozzles are less effective IMO. Stainless is ok, however.

I would listen (very carefully) to @mechanic416 in this regard. He is very knowledgeable about cutters and torches in particular.