Nozzle: normal wear or premature failure signs?

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RAD
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Nozzle: normal wear or premature failure signs?

Post by RAD »

I've recently made my first few cuts on my DIY table. I am using a powermax 800 with the duramax torch. After doing some test cuts and getting acceptable results, I decided to phisically measure my torch height in relation to the voltage on my THC, aparently I was cutting way too high, shortly after adjusting voltage to get correct height I started noticing an increase in kerf width and taper, so I removed the nozzle to inspect and it had etched like markings inside and had a slight nick in the orifice.

I have since replaced the nozzle and electrode with a new set and the cut quality was good again, however I removed the nozzle just to inspect and there were similar markings on the inside but not as bad as the first nozzle then on my second inspection there were more markings. The pic shows the markings after first inspection. 'V' shaped marks

Are these markings normal or is something killing my consumables, the cut looks fine I'm just worried about the markings of being a tell tale sign of premature failure. thanks.
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D.I.Y 4x4 CNC Plasma Table with water tray
60 Gal. A/C + D.I.Y Aftercooler + Water/Oil seperator + Desicant air dryer
45XP (CPC with hand torch)
MiniTHC
UCCNC + Sheetcam + Inkscape / AutoCAD
jimcolt
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Re: Nozzle: normal wear or premature failure signs?

Post by jimcolt »

Absolutely normal. To start the arc there is negative power applied to the electrode, the nozzle is positive. When air flow gets to the torch the air pushes the spring loaded electrode back away from the nozzle, as it breaks away from the nozzle a DC arc occurs, this arc ionizes the air (adds heat, energy) and the force of the air flow blows this ionized air through the nozzle orifice where it creates a pilot arc.

Those marks are at low amperage, the power supply steps the amperage up once the pilot arc is established, then if the pilot arc is within striking distance of the workpiece (connected to the work clamp) the power supply ramps up to cutting current. All very well engineered and controlled for best consumable life. When you change amperage (and nozzle size) these specs change based on the internal microprocessor in the plasma cutter.

Jim Colt Hypertherm
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lockeyone
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Re: Nozzle: normal wear or premature failure signs?

Post by lockeyone »

Just curious on how much steel/metals you guys go through at the plant testing your machines. Do you get to go out and play too?
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RAD
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Re: Nozzle: normal wear or premature failure signs?

Post by RAD »

Thanks for the info Jim, you put my mind at ease, much apreciated
D.I.Y 4x4 CNC Plasma Table with water tray
60 Gal. A/C + D.I.Y Aftercooler + Water/Oil seperator + Desicant air dryer
45XP (CPC with hand torch)
MiniTHC
UCCNC + Sheetcam + Inkscape / AutoCAD
jimcolt
5 Star Elite Contributing Member
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Posts: 3087
Joined: Mon Jul 20, 2009 11:18 pm
Location: North Carolina

Re: Nozzle: normal wear or premature failure signs?

Post by jimcolt »

We melt a lot of material during process testing. The time consuming tests are during power supply development where we have to run live arcs cutting steel, however we developed "liquid cooled copper cathodes" that spin, submerged under water with a live plasma arc running...attached to power supplies that are inside of a HALT (highly accelerated life test)chamber. This testing used to burn plate continuously for 6 to 12 months with as many as a dozen torches running simultaneously. This test puts 6 years of rough, industrial time on all system components on new products before the first one is ever shipped....and with the liquid cooled cathodes we don't have to spend as much on materials! Jim Colt Hypertherm

lockeyone wrote:Just curious on how much steel/metals you guys go through at the plant testing your machines. Do you get to go out and play too?
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