5/8 inch plate cut problems

[grindergary]

Cut a job with PM 105 at 65 amp with book cut speed and pierce height and delay. Seems like the plasma doesn't want to pierce thru the metal as quickly as it should. I start the cut and the pierce will blow thru right away and other times it seems like it will not go thru right away causing the shield and nozzles to be completely damaged by the blow back of the slag.Change out all the consumables and start again and same thing. Tried wiggle in Sheetcam and it helped a little.
Switched to edge start and seemed to help but still not right. Cut everything down to 16 gauge and pierce works fine.

CandCNC system on 4X8 Precision plasma set up. THC works properly on all sizes of metal down to 16 ga. Doesn't mater if THC is on or not as it is with the pierce. Air is clean, pressure at inlet on plasma 120 and doesn't drop much when running.

Any suggestions as to what may be causing this to happen? This customer is talking about some more work in the next few weeks.

Thanks

Gary

[I Lean]

Just a shot in the dark, but try a higher amp process? Seems like if you cut with 85A parts it would pierce faster.

[mdwalker]

Sounds like you may be getting slag on the shield and when it moves to the next pierce you get an inaccurate pierce height.

[jimcolt]

For piercing 5/8" steel with the Powermax using 65 amp shielded consumables you need to be 100% sure that the proper pierce height (manual suggests .18", I suggest .22") never gets closer than the book setting, and that the pierce delay time is (book setting 2 seconds) always correct as well. On that thickness if there is one pierce too close...you will damage the nozzle orifice as well as the shield. The pierce delay....meaning the torch stays at pierce height and does not move in x , y or z during the entire 2 seconds is critical as well. If the torch indexes down or starts moving in x and y before the pierce is complete. similar damage will occur.

The Hypertherm specs for piercing are correct, although I like to play it safe with a bit higher pierce height....as most height control systems on low cost machines are not especially repeatable in regards to pierce height. The specs are tested at Hypertherm to ensure at least 300 pierces will occur with no damge to the consumables.

A few other things to check:

-The Powermax 65, 85 and 105 have auto or manual air pressure.....set it to auto!
-Ensure your air has no moisture. Drain compressor tank at least daily...and if you ever see water when you drain it you likely need a moisture trap or filter inline before the plasma.
-Make sure you are using genuine Hypertherm consumables. There are Chinese companies selling consumables in original looking packages for Hypertherm systems....they do not perform well, and have damaged some torches. If you got them online from a non-Hypertherm distributor, and got a "real good price"....be suspect!
-5/8" is the max pierce thickness for 65 amp shielded consumables. You could go to the 85 amp consumables and pierce faster, keep in mind that all of my suggestions above apply there as well.

I recently did a cutting job with my Powermax85 at 65 amps on 1/2" steel, had more than 1200 starts on one set of consumables. My machine has a very accurate pierce height.

Jim Colt

Cut a job with PM 105 at 65 amp with book cut speed and pierce height and delay. Seems like the plasma doesn't want to pierce thru the metal as quickly as it should. I start the cut and the pierce will blow thru right away and other times it seems like it will not go thru right away causing the shield and nozzles to be completely damaged by the blow back of the slag.Change out all the consumables and start again and same thing. Tried wiggle in Sheetcam and it helped a little.
Switched to edge start and seemed to help but still not right. Cut everything down to 16 gauge and pierce works fine.

CandCNC system on 4X8 Precision plasma set up. THC works properly on all sizes of metal down to 16 ga. Doesn't mater if THC is on or not as it is with the pierce. Air is clean, pressure at inlet on plasma 120 and doesn't drop much when running.

Any suggestions as to what may be causing this to happen? This customer is talking about some more work in the next few weeks.

Thanks

Gary

[grindergary]

Thank you for the reply. I will try the 85 amp set up next time. I have 2 sets of filters set up, one up at the wall where the line comes thru wall and another at the plasma machine.
I have checked for water and oil and all seems to be good.

I cut some 1/4" yesterday and everything worked out well. I cut a small amount of 5/8" last night and increased pierce hight to Jim's suggestion and makes a difference but still blew a shield and nozzle on second try. Just had to try it

Thanks for the help.

Gary

[vmax549]

You MAY have too much pressure drop across 2 sets of filters. Put a gauge at teh machine after the filters to check the pressure drop while running.

Just a thought, (;-)TP

[grindergary]

You MAY have too much pressure drop across 2 sets of filters. Put a gauge at teh machine after the filters to check the pressure drop while running.

Just a thought, (;-)TP

Thanks TP, I will give it a try but first I have a new compressor coming. 120 gallon 2 stage compressor. The other one the motor went for crap and they said they would replace the whole compressor and credit me for the cost so I bought a bigger one since the old one seemed to run all the time. Installing new lines. Hopefully be up in a few days. Electrician will be here soon.

I have installed the tee and a gauge, so as soon as I get up and running again I will check out your suggestion.

Thanks

Gary

[grindergary]

You MAY have too much pressure drop across 2 sets of filters. Put a gauge at teh machine after the filters to check the pressure drop while running.

Just a thought, (;-)TP

I put a gauge on the plasma and when I fire the unit it shows 120 psi on gauge and when running full out it shows me 110 psi steady. I also noticed that there seems to be no water in the compressor tank and it runs intermittently now. the old one ran pretty much steady after starting a cut. Also had about half a cup of moisture in the tank when I drained it every morning.

I have ordered a new head assembly. The long sleeve is square to the plate on the table but the head itself looks out.

Thanks for all the suggestions. I will get it yet.

Thanks

Gary