Tip Slag Finecut nozzles

[fabricator909]

Startong to finally cut some things with the finecut consumables on our PM125, and these things are extremely touchy with the Candcnc DTHC IV. I have cut 20 ga, 14 ga stainless, and 11 ga mild steel with them. First , I noticed the volts had to be higher than book spec in order to keep the torch from diving into the material. Once i figured that out. The next hurdle seems to be slag accumulation on the shield and nozzle when doing long cuts. Once this happens, the slag builds up enough, or the torch lowers down, then touching the material and causing it to come away from the magnetic breakaway. I've tried different parameters, and not sure what is causing the issue. The torch still dives sometimes, but is more consistent.

[motoguy]

Finecuts are more finicky, so any variance between your setup and the one Hypertherm used to create book specs (such as conductive path from arc to work lead, including sheet metallurgy, water splashing, if you clamp directly to sheet or go through slats, etc) will be amplified. You'll just have to play with it a bit to see what your setup likes. Book specs will be dead on...if your system dynamics are exactly like the ones Hypertherm used in their testing.

Regarding the shield and molten metal, I fight this too. The little molten ball will build up on the shield and grow across a long cut. It's like watching a snowball grow as it rolls down a Hillside. Lol It's like rolling dice to see if the cut will finish, or if the slag ball will "catch", and cause the torch to crash.

I have found that spraying the shield, nozzle, and sheet with welding anti-spatter helps tremendously with this. If you use a water table, you may have to apply frequently or use a non-water based version. Some other guys have had even better results with spray-on ceramic coatings. I would like to try that as well.

Also, if you are using the standard electrode, keep in mind the hafnium "retracts" up into the electrode as it's used. This means the torch actually starts lowering, in order to keep the actual arc length the same (because more of the arc is now "inside" the electrode). This means you constantly need to bump the voltage up as the electrode wears, to compensate.

The Copper Plus electrodes don't do this. They actually feed the hafnium to the end of the electrode, thus making sure the arc stays in a "fixed" location relative to the electrode. This means the torch doesn't dive as the electrode wears. I've been very pleased with this aspect of the Copper Plus electrode.

Tom at CandCNC recently stated (on the CandCNC support web page, IIRC) they are working on an auto-sense feature for Linux. Basically, a couple times per sheet it will make a small test cut, sample the voltage, compare it to some parameters, and "adjust" the preset voltage to compensate for electrode wear. This sounds like a neat feature.

I had a friend stop by today and pick up a fire pit. He was admiring the equipment, and made the common "so you just draw it up, press 'go', and it cuts it all out for you!" comment. I explained the CAD/drawing side, the CAM side, the cut rules, cut optimization, nesting, start points, etc. Then I told him, "there is as much, or more, to learn about that. 06" between the torch and the plate, than all the other stuff combined. "

[BTA Plasma]

Moisture is one of the biggest reason you get dives. You can watch your dives on video and watch the actual water come through and change the coloring of the plasma beam. This will raise tip volts and the torch will dive. If you are not using a dryer system that actually works you will see this issue never go away.

[tcaudle]

You may need to raise the recommended cut height. You should use the full shield for the fine cut not the simple ring. Raising the Preset volts raises the cut height. Jim Colt recommends .07 arc gap for fine cut . We cut everything from 14 ga and thicker with 45A consumables. Recently we cut some 18ga and went to fine cut and it took some testing to get things right. You should never get a slag ball on the top.

[BTA Plasma]

I agree. Years ago when we were shipping out floating head machines only we had customers that would use unshielded fine cut consumables and the nozzle would MASH into the plate and after a few times would deform the orifice in the center and that would give a variable you could not consistently control. Tip voltage would change. Shielded fine cut is the only way to cut IMHO.

[motoguy]

This being the correct shield to use? It's the only one I use with Finecut.

[fabricator909]

We are running an air dryer system, plus hypertherms filter on the inlet of the machine. I have messed with raising the volts, decreasing travel speed, etc. I think the slag is mostly coming from cutting thru the slats. The consumables are all hypertherm finecut, shielded for the powermax 125 torch (only one shield is listed in the manual). The nozzle is FLUSH with the shield on this setup, vs recessed on the regular consumables. What are the copperplus consumables?

[acourtjester]

copper plus Interesting this says 1/2" and under, I though they were not for fine cut

copper plus.jpg (7.33 KiB) Viewed 1788 times

copper plus.jpg (7.33 KiB) Viewed 1788 times

[motoguy]

copper plus Interesting this says 1/2" and under, I though they were not for fine cut

Glad I'm not the only one! I too thought they were only for 1/2" and thicker material...until I ran across a post somewhere stating otherwise. Double checking, and up...perfect for the 14ga I cut so much of!

[jimcolt]

Copper Plus are for 1/2" and thinner, any amperage. They work with Fine cut. If you cut thicker than 1/2" (thicker means the power supply produces a longer arc, higher load voltage) the electrode life starts to creep back to the same numbers as the standard electrode.....why pay more money for any electrode that does not last longer?

The 948 shield is the recommended one for Finecuts. It extends slightly lower than the nozzle to allow the ohmic sensing to work and to protect the nozzle from contacting the material. Wipe the shield off periodically, use anti spatter spray so the molten blowback does not stick as easily.

I have been using the ceramic spatter coating, it is expensive but works well. I actually coat the inside of the finecut shield from the bleed holes down, as well as a coating on the outside (not on the face that has to contact the plate though). This seems to eliminate spatter and eliminates the error message "Torch contacted material" that occurs from the occasional piece of metal that gets between the shield and the nozzle from piercing.

Jim Colt Hypertherm

[james.davis]

Where do you get ceramic spatter coating.
Thanks,
Jim

[jimcolt]

I use http://www.borniguard.com products. You can google "ceramic anti spatter" spray and you will find a number of choices. Jim Colt Hypertherm