Sooo, Tell me about Plasma Cutters...

[Zoomie]

Mike, Mark, Ray, or members,
So tell me about plasma cutters? I'd like to know how to tell a good one from bad, what to look for when buying a plasma cutter, What kills'em? Why not a cheapie off Fleabay? And of course, what makes Everlast machines good?
As for what I think I know: It seems they like dry air and not to be fired without metal contact (often). I know one of the questions is going to be: Watcha' gonna use it for? Well to answer, I've messed with everything from boat trailer bunks to stainless espresso machines and everything in between. Or, anything my bandsaw and TCT saw wont cut!

[geezer]

What to look for: IGBT, duty cycle and price as well as service, Don't be afraid about High freq starts etc. that's all bogey man talk going back to the old days, things have improved since then. I have a pp50 and a pp80 the cost and the performace can't be beat by anything else out there.

[performance]

Unofficially, without a ton of research to back my statements, and just speaking from experience, the benefit of plasma cutters are most apparent under 1" of cut. I won't try to go and tell you about speed improvements and the smoothness of cut or anything like that, because a skilled user of a torch can make the same results. The one thing that oxyfuel excels in is that almost any torch, even the smallest ones can manage 2 inches of cut. The strike againt plasma cutters is that only a super large one can manage that. Yes, on the other side of things....in plasma cutters defense, greater travel speeds can be negotiated on thin metals with relatively small cutting outfits. Also smaller kerf, and less heat distortion are huge benefits. There are no limits to what a plasma torch will cut in the way of metals, where oxyfuel depends upon the carbon in the metal to ignite...and carbonless metals do not cut. There is no need for preheat or near the blow back in piercing operations. Also, when compared to the cost of operation of Oxy/Acetylene, they are much cheaper to operate. Another great thing is that most plasmas are very portable...and convenient. Nothing like running out of Oxygen or Acetylene at 4:00 on a Saturday afternoon just before you finish your project.

What kills a plasma? Well, just as with anything electronic they are subject to the same things electronics are. One thing is running on poor power sources, with under Hz or under powered lines, or even spikes.
Cheap import plasma cutters from China are largely based off a design (from my sources) that was created in the late 80's or early 90's by Linde. Linde was forced to sell out some components or designs to have their merger with ESAB approved(keep in mind this is scuttlebutt) by the US authorities. Somehow some Chinese got hold of the basic inverter designs. Inverter technology was new then, relatively speaking in the use of units. It wasn't perfected, and any faults or flaws built into the design have been magnified greatly down the line, as one company in china copied another company in china's design. Eventually you end up with significant weak spots and poorly performing units.

[kenwhite]

Make sure the unit comes with a good high quality torch and consumables since these parts appear to be critical in proper operation. Also make sure the unit comes with a high quality air drying system since this will create issues with torch operation and consumable wear.

While IGBT's are a slight step up from MOSFET technology, an IGBT is really nothing more than a MOSFET connected in tandem to drive a BJT, so there really isn't much of a reliability increase in this upgrade if the MOSFET design has the same maximum ratings.

[everlastsupport]

Air is a key for sure. I good size compressor with a good dryer. We ship a dryer, but never hurts to get a nice one, for your plasma cutting, tools, and painting. You will be glad you did.

IGBT are better for welding and cutting. True, MOSFETs perform better at higher frequencies, but the IGBT at the lower frequencies shine. I agree, with a proper design they both work well.