Plasma Cut Analysis

Tue, 31 Aug 2021 14:35:27 GMT

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I could use some help analyzing my plasma cuts. I have tried a lot of different settings and still don't seem to be getting an optimal cut. The images below were with the following settings:1/16 mild steel35 amps75 psi~ .5 ipmI can get the one side to look Ok, but the other side has a lot more dross than I would like. I have tried all the way from 10 amps to 50 without a big difference in results. Lowering the amps seems to make the cut smoother, but the dross buildup on the back is worse than in these images. I have also tried varying the speed, and this cut seemed to have the sparks flowing evenly down.The 1st photo is of the bottom, the 2nd of the top.Any thoughts on the quality of these and/or what to try next?Thanks,JoMo Attached Images
Reply:If that's only 1/16" thick steel and you are hitting it at 50 amps, .5" per minute is moving the torch WAY too slow.  At that thickness and amperage, you should be moving about 3 or 4 inches per second.  I would knock the amps down and move the torch about 2 inches per second and see if the dross on the backside improves.  Also, clamp a board or straightedge to guide your torch for a better looking cut.  You might also ask Jim Colt at the Hypertherm subforum what he thinks.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Replyefinately way too slow.  The spark stream should just start to deflect a little when you are approaching the correct speed.  Also watch the torch to tip distance, but speed it up a bunch and most of it will go away.  Ditto on Jim Colt, he is the acknowledged guru when it comes to settings and dialing in you set up.BobI'm spending my Kids inheritance, I dont like him that much anyway!!!!!!Enuff tools to do the job, enough sense to use em.Anybody got a spare set of kidneys?  Trade?
Reply:You do not say what type of plasma and consumables your are using.....that is very important as plasma systems do not cut the same....ebnergy density at the arc is different, arc diameters are different, nozzle designs are different.Regardless of the above... your cut speed is way too slow as indicated by the huge heat shadow on the parts as well as the dross. A typical plasma cut speed on 1/16" sheet steel at 35 amps (assuming you have a nozzle in the torch that is designed for somewhere near 35 amps.....not 100 amps!) will be in the 200 to 300 inch per minute range......you have listed .5 ipm (did you mean 5 ipm?)There also are shielded consumables (designed for drag or template cutting at any power level), unshielded consumables (can drag these at 30 amps or less, above 30 amps you should maintain a 1/16" to 1/8" standoff)Attached pics. A Powermax45 torch with shielded consumables that can drag directly on the plate, a Powermax30 torch with a piece of 18 gauge steel cut at approx. 250 ipm at 30 amps....notice no heat shadow on the plate, and virtually no dross.Jim Attached Images
Reply:Thanks for the suggestions and information! Doug, that one was with 35 amps and using a straight edge with 1/16 inch gap from the work (or less). My guess was .5 ips (not ipm!). It took about 2 seconds to cut the 2x6 in half. I will try to complete it in a second and see what happens. Bob, thanks for the confirmation on that.Jim, I went with an Everlast Supercut 50P. Right now I am just using it to cut coupons while I learn to TIG weld. I spent a lot on the welder (Miller) and decided to go a little cheaper on the plasma. I noticed that some cutters have "fine" consumables, but I haven't seen any for the Everlast. One of the downsides is minimal operating doc, so I have been trying different settings. It actually produces a cleaner/thinner cut (on top) at 10-15 amps, but then the dross it thick on the right and left sides on the back. With 35, I can eliminate the dross on the right/back side, and the left/back side has a lot of it, but it is "stretched" out and should be easy to chip off. I should add that I am using 110 v - that may cut the amps in 1/2. Your notes on the heat signature are very helpful - something that I can monitor. Do you have any other things to think about? Some kind of chart that includes thickness, amps, psi and ipm seems like a must for a beginner, but I can't seem to find anything.JoeLast edited by JoMo; 12-05-2010 at 09:55 AM.
Reply:Joe,The biggest issue with your unit is that the only nozzle that is available is designed for 60 Amps output. 60 Amps is just plain too much power for cutting 16 ga steel unless you could move the torch at about 650 inches per minute....not too practical! When you turn the amperage down to anything less than the design nozzle orifice size...then you are lowering the plasma jets energy density.....which makes for a softer arc with a pretty wide kerf. I'm not on here to knock your plasma system....so I won't, but the Hypertherm units do have a choice of nozzles designed for cutting from thin gauge to the heaviest materials so you can maintain arc energy density (necessary for best cuts) on all materials.That being said....I would increase the air pressure 5 to 10 psi (this will help improve energy density in the arc) and turn the amperage level to 30 Amps. At 30 amps you should be able to drag the nozzle on the material.....above 30 amps you will experience "stiction", which is the nozzle trying to weld itself to the plate!Use a non conductive (carboard or plywood) straightedge, pierce the plate with a little standoff, then lay the nozzle right on the plate and pull the torch toward you....increasing the speed until you see the shadow get smaller. At a certain point the dross will disappear, and if you keep increasing speed the cut will not fully penetrate. My experinec with the system you are using (and yes I have done some cutting with a system just like yours) is that it will have a real, narrow dross free speed range.....but there is one.The nozzle (tip) that your system uses will work best on thicknesses from 3/16" to about 3/8". The above technique do develop the best cut should work on all materials. Above 30 amps you should hold a standoff....or you will experience stiction and short nozzle (tip) life.Good luck.....and remember this is a Hyperthem guy helping!   Jim Colt Originally Posted by JoMoThanks for the suggestions and information! Doug, that one was with 35 amps and using a straight edge with 1/16 inch gap from the work (or less). My guess was .5 ips (not ipm!). It took about 2 seconds to cut the 2x6 in half. I will try to complete it in a second and see what happens.Bob, thanks for the confirmation on that.Jim, I went with an Everlast Supercut 50P. Right now I am just using it to cut coupons while I learn to TIG weld. I spent a lot on the welder (Miller) and decided to go a little cheaper on the plasma. I noticed that some cutters have "fine" consumables, but I haven't seen any for the Everlast. One of the downsides is minimal operating doc, so I have been trying different settings. It actually produces a cleaner/thinner cut (on top) at 10-15 amps, but then the dross it thick on the right and left sides on the back. With 35, I can eliminate the dross on the right/back side, and the left/back side has a lot of it, but it is "stretched" out and should be easy to chip off. Your notes on the heat signature are very helpful - something that I can monitor. Do you have any other things to think about? Some kind of chart that includes thickness, amps, psi and ipm seems like a must for a beginner, but I can't seem to find anything.Joe
Reply:Thanks Jim, I really appreciate it (and will consider Hypertherm in the future). The pictures were really helpful as well, I am not even close to that. I might be able to get a 40/45 amp torch for it (not sure on pilot arc) - do you think that would be worth looking into? As expected, I will mostly be cutting UNDER the range that the torch is good for (less than 3/8th).I will re-post after trying some of these things and practicing a little more.JoeLast edited by JoMo; 12-05-2010 at 10:42 AM.
Reply:Joe,Make sure you have downloaded the online new Powerplasma/Supercut manual. From a couple of things you said, it sounds as if you don't have it.  Also dry air is key. What type additional dryer do you have?That unit should cut that at the minimum setting with no problem...But I suggest 25 or 30 amps with about 50-60 psi.  75 is way too much for this torch configuration.  Even at max output, you should not set it more than about 65 psi. The nozzle size is tuned to your 50 amp range...no worries there. Jim isn't aware of changes that have been made in both the torch design and the unit itself. We have customers making sheet metal cuts all the time that are fully satisfied. It is a 60 amp torch at full rating, but the nozzle diameter has been down rated for this unit.  Kerf is very small with this torch.  At this amperage, you can drag the torch.  The SuperCut with Pilot arc is a basic machine, and there is a much better 50 amp unit available from Everlast, but you shouldn't have any problem getting a good cut with this.  Keep moving at a steady speed. It should take little effort to Zip this in half.   With this thickness, you shouldn't be getting much heat transfer at all. A straight edge is a good idea...In a cut like this, I acutally use a plastic speed square as my guide.  You will get a square, smooth cut. And it will actually last a long time on something like this.   They are cheap and accurate.   It looks like your hand is unstable...If you aren't able to get a guide, brace your hands and arms against the table or cut surface so that it isn't wiggling around....Remember, the torch will cut no smoother than the movement of your hands. If your hand flinches, the torch will too...Last edited by lugweld; 12-05-2010 at 01:45 PM.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Reply:Ok, after thinking about your input, and some trial and error, I figured out a few things so far and thought I would post them in case they are helpful to someone else in this situation:1. Using 110, you do have to read the amps as 1/2 the indicated. I can't actually get 30, the best I can do is 26.5 based on the LED display (indicated 53). It may be even less than that?2. 65psi is about the best pressure - 75-80 seems to kill the arc3. Traveling faster is the key, as everyone said. Setting the machine to full power (53) is the only way to do that with my current setup.4. I tried cutting 1/8th inch and I am not sure that 26.5 will be enough. I may need to upgrade my circuit before tackling that.Below are some new images. I cut most of the sides. The inside two are a little worse than the average, but the little bit of dross seems to clean up easily. The width of the cuts is a little larger than I would like - probably due to Jim's thoughts on the 60 amp torch. I would be curious to see what a 30 and 26 amp cut looks like on 1/16th with this machine and a 220 circuit (if anyone has a similar setup). I suspect that I am getting somewhat less than 26.5. Attached ImagesLast edited by JoMo; 12-05-2010 at 01:54 PM.
Reply:Thanks lugweld, I did check their site earlier and see the issue with the manual now. The product entry points to the old manual, but under "Manuals", there is a new one. I still don't see a table, that would be helpful. I posted my last post while you were posting your's, I would really appreciate your thoughts on the conclusions that I came to. And any thoughts on the posted sample. I made it traveling as fast as I could on 53 - any faster and it doesn't cut all of the way through.Thanks,Joe
Reply:The unit is a 110V/220V...Now that you said you are cutting with 110V, it makes more sense.  220V will improve performance.   It is really adapted for 110V and "will work".  I don't recommend it for people looking for 110V only use.  I am not sure on the new 50P, as I haven't tested it yet, but on the old SuperCut 50, you'd could read your actual output while cutting, regardless of setting.  Yes, you will be very limited on output at 110V. If you drag cut this, your kerf will be much narrower.  About 1/16-3/32 is the best standoff distance for this unit.  PM me and I can tell you how to make a rolling guide for this unit that will make this easier.Edit:Just saw the pics....The little holes are made from inconsistent operation.  When dragging (to learn how), drag to you.  It is a more natural motion.  And just tilt the torch slightly so that the trailing face of the nozzle is about a hair or two's breadth off the metal. This will make sliding it more easy.Last edited by lugweld; 12-05-2010 at 01:57 PM.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Replyugweld, those aren't actually holes, they are dross, or slag on the bottom of the cut. I see now how they look like holes in the picture. They do chip right off, so I guess they are not a big deal. I don't always get them (see top cut), so I think with the above settings and some more practice, I will continue to improve. I am dragging it towards me as you suggest, but will try tilting it some to see if that helps.I will also PM you on the roller guide, I am interested.Joe
Reply:Ok, after some more adjustments and more practice, I am starting to get some results that I am really happy with. Here are the settings:1/16 mild steel50 amps (25 actual, I think, but still reads 50 when cutting)55 psi~2 ipsBelow is a picture of the bottom of my latest cut. There is literally no slag now. Tilting the head away a little bit seemed to be the last missing piece. Also, looking at the cut from the side is allowing me to see what is going on a lot better. I do still get a little bump on both sides just after where the cut starts (see top of picture). It does chip off easily. I am starting the arc about 1/4 inch ahead of the work, letting the arc smooth out and then starting to drag. It seems to be caused by the initial contact with the metal to be cut. Any thoughts on how to correct that? Attached Images
Reply:Sounds like you are making progress!  Keep working at it.Jim Colt
Reply:I also have a chinese plasma cutter w/ what looks like a really cheap torch head.  Please understand that I'm a novice and have never used one of the high-end machines....but my torch just looks cheap...ty-wraps holding the thumb switch to the torch head, vinyl tube cover over the hose/lead/signal wire...you know...cheap!Even then, the machine cuts pretty good.  It's just that the cut quality is a little suspect and the consumables don't last very long.  (Could practice improve this???)So here's the question.  To get better cut quality and longer lasting consumables, can you graft a better torch onto a cheap machine? Also, I've been playing with amp settings and travel speed and this seems to help but now I see in this thread that too much air pressure can effect cut quality.  I've been running about 85 psig for everything...is this too much?Miller 211 w/ spool gunMiller Dynasty 200DXLongevity 60i IGBT plasmaO/A w/ crappy chinese torch/gaugesSouth Bend 10K latheGrizzly 4029 10x54 millGrizzly 7x12 hor bandsawangle grnders, bench grnder, bench belt sndr7.5 hp 80gal cmprsor
Reply:What kind of air dryer are you using?  Yes the air pressure does sound high.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Reply:Originally Posted by lugweldWhat kind of air dryer are you using?  Yes the air pressure does sound high.