Plasma cutting and rusty metal

admin

I have a Hypertherm 45 plasma cutter (I just bought it today) & am trying to find out just how clean the metal needs to be. Havent tried it out yet, want to start out properly.Will it cut at the same level as what o/a cuts? (as to how clean the metal is)Most of the metal I have is not terribly rusty, (stored outside) how clean does it need to be exactly? On the dvd that came with the package, some of the metal appears to be pretty 'brown'. Obviously, the cleaner the better, Ive not been able to find any threads addressing this issue. Nothing about this on Hyper's web page either.We'll see what ya'll have to say, thanks.  -corne-
Reply:ive cut threw some pretty rusted material with a plasma at work all the time and also threw paint
Reply:My Chinese plasma does fine on rusty metal even small rust scale. If its really scaly it sputters like a torch.Fireman BillHH 210 MVPMM 211 Spoolmate 100Lotas LTP5000D PlasmaOxy/Accet (Victor)Wards AC/DC buzz box30 ton old hyd pressA few brand name toolsA bunch of cheap toolsA wife to worry me and4 dogs to supervise me
Reply:If you can conduct current through it it will cut. Rusty metal is also hard on consumables, so sometimes cleanup will help. I have cut thru crap with layers of scale and rustholes, but I change to an old set of consumables to do it.Miller xmt304,  Miller S22 p12, Miier Maxstar SD, Miller 252 w 30A, Miller super32p12, Lincoln Ranger 9, Thermal Arc 181I with spoolgun, Hypertherm 10000 ,Smith torches. Esab 161lts miniarc.
Reply:I have used my PM45 to cut up some big 1/4" steel plate boxes.  They were scaly rusty on one side and multiple layers of paint/rust on the other.  Cut just fine and much faster than O/A.  It will affect cut quality and consumable life  though.  I keep a few sets of old consumables around just for cutting stuff like that.  Sent from my C811 4G using Tapatalk
Reply:Unless it is out of a pond with big flakes just grind off a corner to clamp your ground to and let the sparks fly. No problem.
Reply:Just grind a spot for the ground, then grind a small spot for the initial cut. Complete the circuit when you pull the trigger and cut away.  This is what I do when I cut through painted steel.  Once that plasma arc gets going, it will cut.  As someone else said however, heavy rust (and paint) is harder on the consumables life span. "Hey I didn't come to look and learn, I came to turn and burn.... If I can't light up, I'm gonna light out!"-JodyIdealarc 250 "Fatman"MM 252MM 211 "Little boy" Victor Torches
Reply:Mine makes clean cuts right through paint and light rust.  As long as the ground area is clean.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:http://www.trucutcnc.com/downloads/PM45.pdf
Reply:Rusty metal cutting with plasma:- Clean off a small area with a grinder for a good electrical connection with a ground clamp.-If you are using a Hypertherm torch with shielded consumables (Powermax45), then cut the rusty metal just as you would cut clean metal. Use proper technique (tipping the torch to allow pierce blowback to not damage nozzle and shield) or edge start.....then drag the shield directly on the material. Contrary to other posts here....there is no effect on consumable life when using Hypertherm's shielded consumables. With non shielded there will be shorter life.-If your material has more rust or dirt or paint on one side as compared to the other.....put the rusty side on the bottom as this will produce less dross...or resolidified metal. Rust, dirt, paint on the bottom gives the molten metal nothing to grip.....so no dross!In short, using the best plasma technology (shielded, conical flow technology) rust can actually cut better than clean steel.Jim Colt   Hypertherm Originally Posted by cornemuseI have a Hypertherm 45 plasma cutter (I just bought it today) & am trying to find out just how clean the metal needs to be. Havent tried it out yet, want to start out properly.Will it cut at the same level as what o/a cuts? (as to how clean the metal is)Most of the metal I have is not terribly rusty, (stored outside) how clean does it need to be exactly? On the dvd that came with the package, some of the metal appears to be pretty 'brown'. Obviously, the cleaner the better, Ive not been able to find any threads addressing this issue. Nothing about this on Hyper's web page either.We'll see what ya'll have to say, thanks.  -corne-
Reply:Originally Posted by jimcoltRusty metal cutting with plasma:-If your material has more rust or dirt or paint on one side as compared to the other.....put the rusty side on the bottom as this will produce less dross...or resolidified metal. Rust, dirt, paint on the bottom gives the molten metal nothing to grip.....so no dross!Jim Colt   Hypertherm
Reply:Thanks for all the replies, I ,was gonna ask about paint also, but thats covered too.Happy New Year!!!
Reply:I hooked it up yesterday after coffee,  ,  , totally awsome, so much better than gas. Next project will be a cutting table, somewhat portable, maybe collapsable, Any ideas?
Reply:Originally Posted by cornemuseI hooked it up yesterday after coffee,  ,  , totally awsome, so much better than gas. Next project will be a cutting table, somewhat portable, maybe collapsable, Any ideas?
Reply:As others have mentioned, generally the plasma cutter doesn't care too much about rust, but if it's heavy I'll wire brush it off. When cutting down sander boxes that have heavy paint I've found that scoring a line through the paint with a cutoff wheel prior to plasma cutting leaves a cleaner cut. I suspect the arc prefers the clean line so there is less arc wander. I also use the score line trick when free handing as it gives me a nice line to follow... easier to see than chalk.
Reply:I have been 'learning' procedures for cutting. And over the weekend, I noticed when I stop or end the cut, the machine does NOT shut off the air through the torch for sometimes 15-20 seconds. Couldnt find anything in the manual about this. Is this normal? It cuts fine, tho. The local welding store (Matheson), where I got it isnt open yet, so I'll ask them later, but they are salespeople, not necessarially users. -c-
Reply:Yes post flow is normal.  Cools the torch extending life of consumables etc.
Reply:To stop the post-flow, briefly squeeze the trigger. That is NOT explained in the manual, I had to call Hypertherm to find it out.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:The post flow is necessary for consumable life......so try not to make a habit of stopping it by brief trigger squeezes!Jim Colt  Hypertherm Originally Posted by Silicon-basedTo stop the post-flow, briefly squeeze the trigger. That is NOT explained in the manual, I had to call Hypertherm to find it out.John
Reply:I realize the purpose of the post-flow, but to have 15 seconds of post-flow after a 2 second cut is annoying and wastes energy. I always let it run after a long cut.Perhaps your engineers could make the post-flow time dependent on cut time and current, rather than a fixed 15 seconds.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:The post flow is to optimize consumable life. I guess the trade off is to pay for more air (with postflow) or pay for more consumables, (without postflow) on short cuts at low amperage.....shortening the post flow probably has minimal effect. Keep in mind that when you retrigger tha torch...and hold the trigger it will stop postflow and refire immediately.Jim Colt Originally Posted by Silicon-basedI realize the purpose of the post-flow, but to have 15 seconds of post-flow after a 2 second cut is annoying and wastes energy. I always let it run after a long cut.Perhaps your engineers could make the post-flow time dependent on cut time and current, rather than a fixed 15 seconds.John