Powermax 45 vs 1/2" aluminum

[gamble]

Tried this twice today.
cut1 - 45 amps, 19 IPM
cut2 - 45 amps, 24 IPM

At 24IPM the cut was much better, but still you can see the arc at the bottom of the material at about a 20* angle so when it finished the cut it didn't cut the last 1/16 or 1/8" of material. So should I set it to be slower speed?
At 19IPM the dross was terrible. Both times I had to beat the piece out with a hammer and even cut a that small section with a cut off wheel.

The other thing is that half of it has a straight cut, the other half (when the torch moves up (away from me) and to the right has a nasty taper.
The taper on the inside of the circle is pretty terrible as well

Any advice on how to get a better and cleaner cut. One that I don't have to beat the part out of the plate for 10 minutes with a hammer and have less taper. Consumables are pretty much brand new, maybe have 5-10 minutes of run time on them. Air pressure is always in the middle green led.

[Shane Warnick]

I think you need to get a bigger rock. Or maybe, torch. In the manual for my PM85, when I look up 45 amps, it only goes up to 1/4" on aluminum, as well as stainless steel. When cutting on materials other than steel, it is purely a thermal process, there is ZERO oxidation to help burn / remove material from the cut. I think, given that you are cutting material TWICE as thick as the maximum recommended material for that torch at that amperage, it looks pretty good. Not sure you can expect to get it much better, unless you increase to a larger power supply. Looks like a job for a 65 amp process to me. Only other thing I can think of, given the fact that you are cutting that thick, is that cut height would be EXTREMELY important, and your consumables have to be PERFECT and probably all BRAND NEW to even have a chance. One small flaw will be made exponentially worse under the conditions you are describing. As far as the bevel, it's probably a nozzle or swirl ring or shield issue, or last, but not least, the torch is tilted along one axis in relation to the plate. Given the thickness, just a degree or two will show up, and since it's only along one axis I am leaning that way. My table will do that, but only when the bed is no longer perfectly flat, OR I have a sheet of 1" on it, I can't be sure, but I think it flexes just a tad in the middle and can leave a slight bevel along one axis only.

Shane

[gamble]

You know now that you say it, some of the holes on the shield are clogged with spatter and I have no idea on how to remove it.
The cut specs for 1/2" aluminum was 45amps and 19IPM in the powermax 45 manual.
Today I tried some 3/8" aluminum, 45amps and 40 and 30 IPM.

results were nearly the same, just less dross. Doesn't cut all the way to the end, about 1/8" away. Not sharp corners. Nasty taper on one side.

I want to try 1/4" aluminum although it's a lot thinner than I want for this project. urgh. I need a cnc mill

[SeanP]

I tried a small piece of 12mm ally a while back, it was only 30mm square, it cut fairly well, not as much slope as your sample though, I went for 450mm/min (17.6ins/min)
I have unblocked some serious messes from the shield using a gas nozzle cleaning set, had to hold it with pliers to push out the blockages.
I have had that shield since new, it's cut a serious amount of stuff, keep saying it but it's time I had another
Will post a pic tomorrow of the piece I cut.

[jimcolt]

I'll jump in...


Aluminum does not allow for the exothermic reaction that occurs on steel when cutting with an air plasma, rather, it is a thermal (melting ) process only. The arc lags back at about a 15 degree angle when you are cutting at the correct speed on aluminum, if you watch an air plasma arc on steel (when cutting at the right speed) you will see the arc actually leads ahead of the cut...this is an effect of the exothermic burning of steel from the 20% oxygen content in air.

So, when cutting aluminum:

- Pay very careful attention to pierce heights and pierce delay times. Aluminum takes longer to pierce than steel....it blows back on the consumables and tends to adhere to them. Use anti spatter spray....even better use the newest ceramic anti spatter coatings (expensive, but worth every penny) to coat the outside of the shield. If you are clogging the bleed holes in the shield....then you are piercing too close and/or with inadequate pierce delay time. Again....the pierce height and pierce delay times are critical....higher height and longer times are certainly better than not enough.

- Cut height is critical as well. There is some steady state spatter back on the shield....even after piercing. Use anti spatter spray and wipe the front end off periodically.

- On thicker stainless......if the part does not drop it is because of the 15 degree lag in the arc. Some software has the ability to keep the arc on after the motion stops at the end of a cut.....experiment with the timing of this function as it allows the bottom of the arc to catch up with the top, finishing the cut so the part drops.

- 1/2" aluminum is about the limit for acceptable cuts with a Powermax 45 in my opinion. The 65 amp shielded process does a much better job on this thickness.

Jim Colt Hypertherm

[gamble]

Jim, any pictures of some 1/2" or 3/8" aluminum that you have done with the 45?
Is there a way to avoid the taper on the one or two sides?

I should mention this was an edge cut
Height was pretty close like .05-.06

[Robert]

Jim I’m going to cut 3/4” aluminum with hyperthermia 65.
On a water table. A square in the middle. Is there something I need to know?
First time cutting aluminum
Is it bad on the torch?
Thanks

[robertspark]

3/4" aluminium with the pmx65 is edge start only.... You may be best to drill a pilot hole starting point for the center cutout.

Note you resurrected a very old post from 2015!

[Robert]

Thank you