Plasma cutters work by sending a pressurized “gas” (in our case compressed air), through a small channel. In the center of this channel, you’ll find a negatively charged electrode. When you apply power to the negative electrode, and you touch the tip of the nozzle to the grounded metal (or a pilot arc touches), the connection creates a circuit. A powerful spark is generated between the electrode and the metal. As the inert gas passes through the channel, the spark heats the gas until it reaches the fourth state of matter. This reaction creates a stream of directed plasma, approximately 30,000 F and moving at 20,000 feet per second that reduces metal to molten slag. The plasma itself conducts electrical current. The cycle of creating the arc is continuous as long as power is supplied to the electrode and the plasma stays in contact with the metal that is being cut. The cutter nozzle has a second set of channels. These channels release a constant flow of shielding gas around the cutting area. The pressure of this gas flow effectively controls the radius of the plasma beam.
What does this mean to you? That small, intense plasma beam is extremely powerful and can cut through metal with ease. This also means it can wear out consumables. We get calls from time to time about customers that have had issues with their plasma cutters. The symptoms are often that the plasma cutter won’t initiate an arc on the metal, or the arc will start and stop erratically while you’re cutting. I decided to put together a few causes for those sort of issues. Hopefully one of them can save you time when diagnosing an issue with your plasma cutter.
1.Initiating an arc with no or too little air pressure- Without the air to cool the consumables the arc alone can super-heat the electrode and burn up the tungsten found in the center of the electrode almost instantly. It can happen easily and in an instant. Say you forgot to flip the pressure valve to feed your airline and hit the trigger once or twice before realizing what the issue is, you probably damaged your electrode.
2. Too slow of travel speed when cutting- Moving excessively slow when cutting (especially at higher amps) overheats the torch consumables and can cause the parts to wear out prematurely. It can also cause the arc to terminate.
3. Dragging the Torch Nozzle on work piece- This is a common mistake beginners make. It can overheat the nozzle and it also exposes the nozzle to an abundance of slag which can wear it out extremely quick.
4. Inadequate Water separator or air dryer on compressor or internal separator full. Water in the air stream will “put the fire out” in the torch. It can cause the arc to be erratic and unstable and may seem like the plasma cutter isn’t working correctly. Make sure at the least you are running a small disposable in-line water separator or upgrade to a desiccant system on your compressor. The internal plasma cutter’s separator should be checked or drained periodically.
5. Too long or small of an extension cord being used on the machine- If you have a low quality, thin gauge extension cord or too long of a cord the machine could have trouble initiating an arc or it won’t cut metal as thick as rated or the settings on machine don’t match what it can cut.
Below are some samples of bad consumables. If your nozzle has an elnlarged, oblong, or otherwise gouged out center it will cause the plasma beam to wander and will lose it’s punch. If you allow it to get too worn like seen below, it will burn a divot into the center of the electrode, thus burning out the conductive tungsten that’s creates the arc in the electrode. Lastly if you get the torch too hot or you light up the torch with no air pressure it can overheat and melt the swirl cup/diffusor and it may look something like below. This will cause the air to fail to mix in the torch and will make an unstable arc. The moral of the story is to be sure to inspect your torch parts regularly and make sure that none are worn out.
last time I used my plasma cutter there were no problems. today I turned it on and the air started flowing through the nozzle and did not stop until I turned the machine off. cannot start an arc because the air is always on. unplug the air relay and the air stops so the relay is good. what could be the problem?
I have a miller spectrum 375 plasma cutter and ice-27C torch. When I start cutting every 5 to 10 seconds it goes out then comes back on then goes out again. Why is that?and what do I have to do help please thanks
Hi Dave,
Our machine has a built in safety timer (for lack of a better term) that will require you to let the air flow stop before reigniting the torch. This is only when it senses the circuit is broken for too long and the torch isn’t cutting. It is meant to save the torch and machine from damage by leaving the high-frequency pilot arc on for too long. A poor ground, excessively dirty metal, or worn out electrode or nozzle could cause an issue with poor arc start.
I have a Versa Cut 40. If it loses the arc or I stop a cut I have to wait until the air flow stops for the machine to again strike an arc. As long as I’m cutting it will keep the arc but once I stop I have to wait for the air flow to stop to begin again. Its frustrating when making short and numerous cuts. I have replaced the electrode and the nozzle but it still does it. The diffuser has some burnt spots on its edge. What could be my problem? Thanks…
Hi usually a poor ground or a bad/worn out electrode will cause that. Please email our tech team and they can walk you through the diagnosis. Techelp@eastwood.com
Have you changed all of the nozzles and electrodes out? Usually a worn nozzle or electrode will cause that.
Hi wondering if anyone can help i am in AUS and have a boc cut 40 machine i have had it for about 5 years i do not use it much because eveytime i do the cut that i get is always on a angle. I changed my gun to a cheap ebay gun and this sort of corrected some of the problem. Any help would be great.
Thanks.
P.s this still happens with guide wheels.
My eastwood plasma cutter was working this morning and now won’t struck an arch. I changed the consumables and checked connections, what’s my next likely cause? Thanks
So nice post,very informative and helpful to me thanks for such a good post.plasma is best for cutting it works reliably for metal cutting.
My post air on my versa cut 60 stays on until I power down the machine. after I cycle the power it will be off until i cut again. What can I do to fix this? My air pressure is 60psi and the machine is running off of a dedicated 50 amp circuit with 6 gauge wiring so I don’t thing power is a problem. I am needing to use this for a couple weeks before I could send it back, i cant be with out it for 2 weeks at this point. If I send it back right now I might as well just return it and buy something else.
1/16th to 3/32 is acceptable.
Using the Plasma #40, without the “Cutting Guide”, what is the proper tip to work distance for 18 gage material?
The Eastwood Versa-cut 40 is the workhorse of our shop. We almost always use new consumables for our projects. It seems expensive, but you have to consider how much you are saving by not having to buy near as many cutting and grinding wheels and drill bits.
all questions and answers were very informative. like all of your articles. thanx fer all the info
Ideally the torch should be as “straight” or perpendicular as possible but it’s often hard to see where you’re cutting. Torch angle should be as minimal as possible with it favoring the “straight” side of the cut (there’s a straight and angled side of a cut with a plasma cutter).
That’s a great tip Larry!
It all depends on what you’re cutting, how long the cuts are you’re making, cleanliness of the metal, etc. The key is to make sure you’re checking them regularly so your plasma cutter performs its best.
Since I am new at plasma cutting, how long should my consumables last?
Great questions & answers generated here Matt. I would like to say to all, as well, practice and experiment on like kind materials as your project and make your adjustments as needed before getting into your actual project material. Pay close attention to all variations as you go from one project to another and soon you’ll be able to set your machine right off the git go for any new job.
Great info thank you
Thanks for the help. I see I wasn’t very clear, use it in a CNC machine, & also by hand. In both situations I’m having this issue. I’ll double check the CNC to be sure it’s squarely mounted.
I use mig dip on the nozzle and it helps keep spatter and such from sticking and pitting consumables
Thanks for the info.
Should the torch be held perpendicular in all directions? I am use to an acetylene torch and on very thin metal I hold the flame into the cut.
There are 3 tips for a plasma cutter one is a dragging tip where it can touch the metal,gouging for cutting welds and a cutting tip where you hold it above the metal and do not let it touch or it will ground out and ruin the tip
The cleanliness of the metal you’re cutting makes a big difference. The more paint, grease, rust, etc that your torch has to cut through, the more slag or spatter it can cause. Also make sure that your air pressure and amperage are high enough that it can EASILY blow through the piece your cutting. For the cleanest cut I always start with new consumables. Especially when cutting sheet metal where I need to be ultra accurate. I’ve also used a straight edge and set my torch up so the edge of the cup can ride against the straight edge as I cut to make sure that my hand doesn’t wander during cutting.
Hi John, you may need to check your air pressure while the machine is cutting or an arc is initiated. Often times too low of an air pressure will not push the molten metal or slag away from the cut completely and can backfill the cut or stick to the edges causing excessive cleanup.
Extended nozzles help get into tight areas and also allow for better visibility when cutting.
The picture shows new and badly worn/damaged parts to show the difference.
Hi Jaison,
The handle itself wouldn’t cause that. If you always hold the torch and cut at the same angle it will always wear the nozzle the same. Similar to how your heel of your shoes may wear out quicker than the front if you drag your heel. That side of the nozzle is seeing most of the heat and sparks while cutting so it will wear that edge away the same. Hope that helps!
My plasma cutter recently started to cut on an angle. I’ve replaced all the consumables in the handle, which helps for a very short time. It wears the hole in the tip to one side & the cut leaves an angled edge on the material. Should I replace my whole handle next?
The problem I had to work through was initially getting the air pressure correct. My air system pressure into the regulator on the plasma cutter was too high for the cutter regulator to drop fast enough. result was it would blow out the torch before it could drop pressure fast enough. Fix was a second air regulator on the air line to feed cutter at lower pressure so torch regulator would work correctly. 🙂
In the second picture, what is wrong with the first and third consumables? They appear fine. In fact the third one (nozzle tip) looks brand new.
Could you shine a little insight on extended tips and nozzles? Theres not alot of info on this. Thanks!
Matt — How do I prevent slag/molten metal from back-filling the cut? What am I doing wrong?
Good tips, perhaps you can answer my question. Why is it on all the car shows when they are using a plasma to skin a quarter etc. the cut always comes out clean, tight and no bleeding edges and requires minimal grinding..I have an Eastwood 40 and no matter what the setup is my edges are jagged, slaggy and the cut is wide..requiring either cleaning up with a cutoff wheel or excessive grinding ?
Great tips on plasma cutting….I have just learned a lot about consumable damage!!
I have both your 40 & 60 amp plasmas.
They work great as do your mig175 and 250amp!! Spool guns are a dream to use also.
Thanks for all the great info on your products.
Ed
BC Canada
I like y plasma cutter. it works well. I dint have to buy gas for my tor my torch.
Hi Mark,
This means that the plasma cutter can “jump” the arc and does not require you to drag the tip to initiate an arc. This high frequency start also allows you to start an arc on metal that isn’t perfectly bare, clean metal (for instance cutting out an old rusty floor). I generally like to make an “entrance path” cut if it’s something that you want to cut a shape out of the middle of a panel. Starting directly on your pattern can cause that first cut to be a little larger than needed. I start just to the side of the piece and once I have the cut started and controlled I work over to my shape and cut it out, always worked well for me!
Hi Tom, which plasma cutter do you have, we can happily send you a set of instructions if you’d like more info on where the internal separator is.
Good point, the tips we include can withstand dragging, but the point I’m making is that dragging them for long cuts, especially on dirty metal, or on thick materials where the plasma stream may not cut all the way through instantly can cause premature wear of the nozzles, electrodes, and diffusors. There are times when dragging is necessary but doing it 100% of the time can cause the parts to wear out faster. Good point, I’m glad we could clarify better for other readers!
Helpful hints are always greatly appreciated.Thanks and keep up the great work.
Eastwood is an awesome company..
IN the answer to bill, you mention that your plasma cutters have a ‘high frequency start’. What is this? What is the best way to start a cut from the middle of a piece of 1/8 hot roll steel?
Thank you
3. Dragging the Torch Nozzle on work piece- This is a common mistake beginners make. It can overheat the nozzle and it also exposes the nozzle to an abundance of slag which can wear it out extremely quick.
This statement is not TRUE as the tips sold by Eastwood are made to DRAG on the metal being cut.
I have an eastwood Plasma cutter it came with a small water separator but it did not tell me were to put it , Can you help me with this . Thanks Tom
Generally holding the torch tip just above the workpiece is more ideal and will double to triple your tips lifespan. Our plasma cutters have a high-frequency start and do not require “scratch starting” or dragging the nozzle like some others on the market. Hope that helps!
You say “dragging the nozzle on the work piece” is incorrect; I thought that is how it is used. What am I missing?
Very informative and helpful. I have a used plasma and have had limited success from it eating my tips like candy. I now know a little better what I should be doing. Thanks and keep the info coming. I’m a long time Eastwood customer and fan, Trevor in Alsip is THE man.