Plasma Cutter Solenoid

admin

I have a Chinese 80 amp IGBT plasma cutting machine with an annoying problem: the air solenoid in the unit takes too long to shut off (minutes), and it wastes too much compressed air.  Is there a potentiometer inside the unit to control the timing? There is nothing on the outside controls to adjust this.
Reply:Congratulations on your post that lacks any and all relevant information. Welding/Fab Pics: www.UtahWeld.com
Reply:Do you mean this is the wrong subforum?  I figured as much.The unit is a LTP8000 from Lotos.  Surely someone here must have some experience with the Chinese plasma internals.
Reply:No. Surely you're aware that you're asking questions that cannot be answered w/o us at least knowing what make/model the machine is... think maybe that would be pertinent information to include? lolLast edited by MikeGyver; 08-01-2011 at 02:03 AM.Welding/Fab Pics: www.UtahWeld.com
Reply:Well one of the first things you should do is pop the cover off and pull the solenoid out and either replace it or hook it up to a DMM to test whether it is the electrical current that is causing it to continue to run on after the cut has finished or whether their is a problem with the mechanism inside the unit holding the solenoid open.If your machine does not have a post flow timer to adjust then their would have to be a potentiometer on the inside, follow the wiring back from the soleniod to the circuit board.If their isn't a pot then their would have to be a simple resistor-cap timer circuit w/relay.Where did you buy it aqnd do you not have warrantee coverage?Their is usaully foru screws or rivets holding the solenoid together, Remove them and clean the unit, replace o-ring.alsoGet over to Simon at Longevity-inc.com, maybe he can help you as they are very generous with his time advising on other import machines.One of the problems with this import welding machines is that they work very well but alot of problems occur because quality control is not the same as with domestics welding equipment.
Reply:Keep in mind that the air continues to run after you have finished, to cool the torch and consumables. Shortening this time may save you air, but at the cost of the consumable life. Not realy a good trade off. I'd be surprised if the machine was "broken" and acted this way. Usually when something like this fails electronically, it either doesn't work at all, or it just stays on full time. If the machine is functioning properly, then there's a reason the designer set it up to run this long..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thanks, DSW I am aware of the postcooling function of the air similar to the way argon is used to cool (and also post-shield) a Tig torch.  However in this case, the post-flow is simply uselessly long.  We're talking at least 60-90 seconds for a pretty short cut.  I'd say there must be some adjustment pot somewhere but I don't want to open the unit and void the warranty unless I'm darn sure it's going to do some good.It works great, just the postcooling is too long.  What I'm really asking is if there is anyone out there who has toyed with Chinese plasma PCBs enough to have experience with the solenoid timing controls (if there is a control in the unit or not).Last edited by Tester0; 08-01-2011 at 10:20 PM.
Reply:On some units post flow is a function of amps used not cut time. I believe thats the case with Hypertherm units but I could be wrong. I know mine will take the same length of time for post flow if I strike an arc but don't cut or if I cut for 3 or 4 minutes straight. If you are cutting at max amps like many do, that would equate to longer post flow. Does the flow time change if you decrease the amps? The machine may also simply be set up for worst case senario..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Don't have it hooked up right now to check, but last I was using it, it was running only 30-35 amps, and it was still taking a damn long time to cut the postflow out.  It has an 100 amp torch, it should not need that kind of postflow time.
Reply:It might be dirt in the solenoid or it could be rust from moisture.   Do you have a dryer on the line?  I'd also consider the fact the solenoid may have a wrong spring, or too short of one.  Try stretching it an 1/8" or slightly less.  I don't think its on the PCB.  Try tapping on the machine or the solenoid when the cover is off with a screw driver after the arc is activated and post flow begins and see if it cuts off.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:No dirt in the solenoid, no rust.  Machine is pretty new actually.  Have a small Wilkerson ~6CFM dryer on the line with a filter-regulator combo right before it.  Air is already reasonably dehumidified, and not much water is coming out of my compressor when I drain it.  Nothing really reaches the filter or the dryer, I think we can totally write-off moisture as a problem.  In fact, you seem to be moving me further away from my instincts.  I am telling you this is a timing problem.  The solenoid is energized too long, that has to be it.  The solenoid is inside the unit by the way, I have not opened it yet, but I am pondering opening it now although the warranty is at stake.
Reply:how much input air pressure are you running?tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:60-65 PSI.  The American units are supposed to demand 70+ PSI but I'm not too sure why they say that.  Usually Chinese units are supposed to be happy with pressure from about 60-75 psi from what I've read.