Need to buy a CNC plasma machine - Are the Chinese any good?

digger doug said:

Torch lifting = THC Torch hieght control

Yes, you want it.

slow starting versus fast (instant) starting = older HF plasma power
supply vs newer plasma power supply (and torch)

You want the "instant on" and you want a hypertherm power supply & torch.

Click to expand...

digger doug said:

It's not "Powerfull"
It's "long lasting consumables"
It's "Fine control of that power"
It's "Unique design of the complete system"
It's "Fine cut"
It's "Less dross"
It's "Faster cutting speeds"

I did answer all I know about chinese machines.
Get one with THC, and one that comes with a hypertherm
supply & torch.

Click to expand...

Strostkovy said:

I cut 1/8"-1/4" 5052 on my plasma table all of the time, using a Hypertherm Powermax 85 torch and a low end plasma table.

The cut quality is nice, but note that the drag angle (not the bevel angle)in aluminum is terrible, so as you go around corners, and especially small holes the bevel becomes quite bad, so expect to go at slow speeds.

I cut three 5' x 10' sheets of fairly intricate parts per set of consumables (~$10) and hold +-0.005" tolerances on stuff that I need to. I think I'm around 2000 pierces per consumable set. I'm not sure what the published specs are. We can press PEM nuts into holes in 1/8" sheet.

I personally cut all aluminum at 45 amps (finecut for 1/8), at 54, 85, and 100 ipm for 1/4, 3/16, and 1/8 respectively. This allows me to set the part on a flat table on its edge and have it not fall over.

The burr is very, very minimal, and is on par with an old CO2 laser I've also made parts on. Top dross is a little bit more of an issue than on a laser, but it can be wiped off with a towel. I currently deburr with a pneumatic angle die grinder with an 80 grit sanding wheel until I eventually get my timesaver running.

Expect very nasty globs of dross where the cut crosses over a steel slat. You may want to replace the slats with something pointy or possibly aluminum.

Torch Height Control is absolutely critical. Do not buy a machine without it. There is about a +-0.015" window of height above the metal where you get the best cut without instantly destroying consumables.


I know this doesn't directly answer the question, but I hope it is useful information. I can show you pictures of our typical cut quality if you would like.

EDIT: regarding low budget US plasma tables, I agree. They seem to have the same issues I would expect from a Chinese machine, and are built equally poorly. The only advantage is support, which you still may not get.


Oh, and one more thing: water tables. I cut on a water table. Aluminum dust spraying into water, especially when the water is hot, will cause a chemical reaction where the aluminum pulls the oxygen out of the water and releases hydrogen gas. The water tables are effective at keeping a lot of the smoke down, but regularly explode when cutting aluminum. After cutting up 7 sheets of 1/4" aluminum, I had three hydrogen explosions while cutting the last sheet alone. These explosions are often powerful enough to move the sheet, and in one case has picked up a sheet of metal and slammed it into the torch when it pierced. After cutting just those seven sheets (10 hours of cutting or so) the water was hot enough and contained enough aluminum that hydrogen production was very profuse. I decided to let the machine sit for half an hour and cool off a bit before continuing, but the heat produced by the reaction with the aluminum was apparently enough that the middle of the table had come to a rolling boil, and there was nothing I could do to stop the reaction other than wait it out.

The chemical they suggest to add to the water to prevent rusting of steel also causes ugly corrosion spots on aluminum. It powder coats, paints, and MIG welds over it fine, but it looks terrible. If you don't add this chemical, parts of the machine and table will rust.

The advantage of water tables is that they keep parts cool, but honestly the hassle of drying off parts and the constant mopping and explosions isn't worth it.

So in short you should avoid a water table. Be aware that plasma cutting aluminum makes far more smoke than steel, and tends to travel farther, coat everything in the shop, and be a bit more abrasive. So you will need a very good ventilation system.

Click to expand...