PM45 Cut Quality

[MajorMetal]

I am having issues with the cut quality on my PM45. I have cut hundreds of 24 gauge 4 x 8 sheets with this plasma with no issues. I installed a downdraft on my Dynatorch SuperBee 4x8 and it seems like this is when the issues began. I previously cut on a water table and never had any problems with these 3 things. I am having issues with my torch height control, issues cutting 7/32 to 1/4 holes and issues with very sharp dross. The first two issues are sporadic - the THC will be working fine and then all the sudden it will quit working and the torch will crash. It will cut one hole perfect and then the hole right next to it will have some jagged edges and maybe a slightly different size. Dross is minimal on the 24 gauge but I am now getting some razor sharp spike like protrusions on the back side.

I spoke with Dynatorch and they seem to think it may be with the PM45 since since the issues do not occur all the time. He suggested a DC clamp on meter around the work lead but I do not have a DC meter. Any thoughts or suggestions before I go purchase a meter? Thank you in advance.

[Gamelord]

First things first. Have you tried new consumables? Is your air pure and constant, no drop in psi? Is your material properly and securely grounded?

You say this started when you switched to a downdraft, have you tried cutting with the downdraft turned off?

Just things to start at. Hope it helps.

[MajorMetal]

I change consumables more often with the downdraft as I seem to go through them quicker on the downdraft. I use twice as many shields on the downdraft as I did on the water table. I am running my air thru a water separator into a Quincy refrigerated dryer and then thru a Motogard M60 air filter. The PM45 shows the air to be fairly constant and I have recently switched to actually putting the ground clamp on the sheet itself. I used to have the ground just clamped to one of the slats and never had an issue. It is a fairly new clamp as well.

I have not tried cutting without the downdraft. I will try that.

Everything I have read has said the cut quality should be better with a downdraft but I have experienced the opposite.

Thank you for the suggestions.

[jimcolt]

Generally downdraft applications will produce longer consumable life as compared to water table use. Can you post some close up pics of a used nozzle orifice and the face of the nozzle, as well as the shield orifice and the inside of the shield? these may indicate to me what could be happening. I use a downdraft with my Powermax85......I am on the second shield after 6 years of cutting, I would estimate that I have used about 120 nozzle and about 80 electrodes in that period of time. When pierce height, pierce delay and cut height are all operating correctly there should be very good shield and nozzle life. I have never attached the work clamp to the material, mine is bolted to the machine frame. Jim Colt Hypertherm

[MajorMetal]

Yes, I will post some pics in the day or two. Thank you Jim

[MajorMetal]

Jim - Here are some photos. I emailed these to you last week but it must not have gone through. Please let me know if you have any questions. Thank you.

Nozzle.JPG (58.32 KiB) Viewed 987 times

Nozzle2.JPG (61.68 KiB) Viewed 987 times

Nozzle3.JPG (56.03 KiB) Viewed 987 times

Electrode.JPG (70.77 KiB) Viewed 987 times

Shield.JPG (64.05 KiB) Viewed 987 times

Shield2.JPG (59.76 KiB) Viewed 987 times

[jimcolt]

The nozzle is severely cratered on the arc exit side...this indicates that the pilot arc is staying on too long which is most often caused by having the mode switch in the "expanded metal"cutting position, but can also be caused by the pierce height being too high or pierce delay being too long.

I suspect some kind of air contamination as indicated by the heavy black swirl marks inside the nozzle and on the face of the electrode. Light gray swirls are normal, yours are very dark, which could indicate some oil in the air system. Look for signs of oil or water in the plastic onboard filter bowl.

It looks like the shield has some blocked vent holes...this causes dross and edge angularity. If you can pick the dross out of the holes usually they can be reused, however drilling the holes will affect performance.

How many starts, how many inches (guess is ok) on these parts? Jim Colt Hypertherm

[gamble]

Jim,
what's the best way to clean the vent holes on the shield?

[muzza]

Jim,
what's the best way to clean the vent holes on the shield?

I have had great success by just soaking them in my Hydarochloric (muriatic) acid mix for about half an hour an then blow out with compressed air. I have shield that have done thousands of hours cutting and been soaked many times.
Murray

[motoguy]

I clean mine in muriatic acid as well.

[SeanP]

Great tip Murray, I must say using the mig tip dip on the shield is really helping me, I use a brush and actually apply it right up the retaining cap as well when its warmed up, the retaining cap I'm using now is still perfect and it's done a lot of cutting, prior to using this the area where the ceramic meets the black would soon start to break down, perhaps from the splashing water as well.
It's so much easier cleaning the cap now, just a wipe, quick touch with the fingernail or scotchbrite at worst and away again.
Not seen any evidence of holes blocking from using it at all, well worth using.

[jimcolt]

The holes actually should never get plugged. When pierce height and pierce delay times are set right....no material will hit the part of the shield where the vent holes are. The stuff plugging the holes is usually steel, which does not stick to copper. I suggest picking the material out with a dental pick. If the holes get plugged, expect that you also will find steel down on the bottom inside of the shield as well....this can short the nozzle to the shield which will cause varying cut angularity....and must be cleaned out. Best bet is to be sure your pierce height and pierce delay times are as suggested in the cut charts in the operators manual.... Jim Colt Hypertherm

[MajorMetal]

It definitely is not in expanded metal mode as I have made that mistake before and always check when turning on the machine. My pierce height is 0.15 (according to the Dynatorch software) and there is no delay as i am cutting 24 gauge. I will pull the cover off and check the onboard filter bowl. I have never checked it before and it has cut for hundreds of hours. I am running my air thru a water separator into a Quincy refrigerated dryer into a MotorGuard (toilet paper roll style) filter. I also have a small MotorGuard filter right before the air enters the PM45. I will try the mirror trick to check the air.

Yes, the shield gets blocked vent holes very often. Each time before i start cutting I attempt to clean them with a acy/oxy torch tip cleaner. If they are plugged then i usually cant get them unplugged and have to get a new shield. On the rare occasions that i cut anything bigger than 16 gauge the shield vent holes really plug up quick. I will try the muractic acid. After each sheet I cut i take a piece of steel wool and clean the shield and that seems to help.

I would guess around 500 pierces and 15,000 to 20,000 inches on these consumables. All on 24 gauge.

Would this also explain the torch height control not working consistently?

Thank you

[muzza]

Yes, the shield gets blocked vent holes very often. Each time before i start cutting I attempt to clean them with a acy/oxy torch tip cleaner. If they are plugged then i usually cant get them unplugged and have to get a new shield. On the rare occasions that i cut anything bigger than 16 gauge the shield vent holes really plug up quick. I will try the muractic acid. After each sheet I cut i take a piece of steel wool and clean the shield and that seems to help.

Have you physically stopped the machine and manually checked that it is acutually running at these heights? Actual height is far more important than set volts.
I would think that going by this statement and your shield photos that you are piercing too close. Also the oxy cleaners can damage the holes, I think you will find the mauratic less savage strangely enough.

I would guess around 500 pierces and 15,000 to 20,000 inches on these consumables. All on 24 gauge.

Generally on light gauge as in 16 to 12, I would get at least 4 times that amount of pierces using book heights and zero delay. I don't cut much 24 gauge but when I do I run at 30 amps and pierce at cut height with zero delay.

Would this also explain the torch height control not working consistently?

I would suggest the opposite, it is more than likely your height control not working properly or accurately that is causing the nozzle wear/ damage

Just my thoughts,
Murray

[MajorMetal]

I will try those things. Thank you for the response Muzza.

[muzza]

Just to update on pierce count, I run Neuron THC which gives me a count of pierces so I asked my guy on the table to reset and write down the pierce count since I posted this last week. He has changed out two nozzles and electrodes and been cutting mostly 16 and 14 gauge but some 1/8" and 3/16". First set 4868 pierces before being changed, second set done today at 3724. Both were still cutting at that point but kerf width was growing so they were changed out.
Murray

[MajorMetal]

I am still having problems with these issues. I previously failed to mention that I am cutting galvannealed. Could the zinc coating on the galvannealed be causing these issues? These issues came up when I switched from a water table to downdraft. Could the water have been somehow trapping the zinc coating? And if so why wouldn't the downdraft pull the coating down thru the fan?