Plasma? filling in behind the cut

Tue, 31 Aug 2021 15:44:06 GMT

go to see Welding Machine for Plasma? filling in behind the cut

Cutting 12 gauge steel (old oil tanks).  Wow, kicks the snot out of a sawsallI can't be to far off with my settings and travel speed because most of the cuts are clean but in some areas it is filling in behind the cut.drag tip40 amps80 lbs air pressureabout 2-1/2" per second travel speed
Reply:Originally Posted by stefuelCutting 12 gauge steel (old oil tanks).  Wow, kicks the snot out of a sawsallI can't be to far off with my settings and travel speed because most of the cuts are clean but in some areas it is filling in behind the cut.drag tip40 amps80 lbs air pressureabout 2-1/2" per second travel speed
Reply:GreenI'll bump up the pressureDrop the amps to what 25-30???I'll try to move faster like 3-4 in per second???Now I want a small cnc rig to play with
Reply:Give yourself a slight "push" angle to blow the slag out of your kerf. It is not un common for me to hold my OA torch at a 75 degree angle on thin stock to blow the slag out.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Your settings are good, Air should be 65/75psi  no more then that. I have seen this on some old steel, slow your speed down a tad and it will be fineIts scap not a need for clean cutswww.georgesplasmacuttershop.comPlasma Cutter and Welder Sales and Repairs--Ebay storeTec.Mo. Dealer Consumables for the PT and IPT torch's
Reply:Originally Posted by mechanic416Your settings are good, Air should be 65/75psi  no more then that. I have seen this on some old steel, slow your speed down a tad and it will be fineIts scap not a need for clean cuts
Reply:I'd be taking tthe sugestions of Mechanic416 ( no offence Mondo ), but 90psi seems a little high for any plasma torch. He works with a lot of different plasma cutters and knows them very well.
Reply:One problem with a drag torch is that you can't really see what's happening. Have you checked the consumables... are you sure the cut is back filling vs not really cutting? Worn combustibles will be inconsistent on a cut. Speed sounds fine... unless the machine isn't really up to the 150 ipm. In ideal conditions you should be able to get 200 ipm on 12 gauge at 40 amps. Slow speed doesn't generally cause back fill as much was kerf growth and dross. Too fast and you skim the surface never making a complete cut. It's hard as a human to maintain 150 ipm (12.5 feet per minute). I doubt your running too fast. Air sounds a bit high. I normally run around 65 to 70. Too much air may cause the cut to cool abnormally quick. Is the metal clean? When we cut down tanks we generally run a score line down the cut with an angle grinder... exposing clean metal... the cut goes was faster and cleaner. Cutting through thick paint and rust can cause problems sometimes.Bottom line. Check your consumables.
Reply:OK...we still don't know what brand and model plasma...so offering advice is difficult.Also...there are two air pressures on every plasma cutter....the raw inlet pressure....which should always be between 90 and 135 psi (from your air compressor), and the torch pressure which should be set based on your plasma systems operators manual. Each brand / model will be different. Most are set at 65 to 70 psi with air flow at the torch, and some have fully automatic setting.If the kerf is filling in behind the cut...and you have more power....turn the power up. Generally idf you are just scrapping something (dismantling) more power means more speed. If you are trying for best cut quality...then you would match the power to the material...and control your speed accurately.Jim Colt  Hypertherm
Reply:Originally Posted by LarryOI'd be taking tthe sugestions of Mechanic416 ( no offence Mondo ), but 90psi seems a little high for any plasma torch. He works with a lot of different plasma cutters and knows them very well.
Reply:Originally Posted by MondoI stand corrected.   In review my PowerMax 30 manual calls for 65psi mininmum to 80 psi maximum.  https://www.hypertherm.com/Xnet/libr...file=HYP104525  Page 2-3 (English).  I cannot explain why I was thinking 90 psi minimum.I guess I will need to turn down my air input regulator.  - Mondo
Reply:Yes  Mondo, the supply air can be as high as 135 to 150psi depending on the machine. But I have found that around 120psi seems to work best. Knowing that most air compressors drop to 90psi before restarting I tell my customers to run at least 1/2" main air line to get the volume needed. Because you need volume as well as pressure.      I have found that almost all the plasma cutters on the market will do the best cutting ( if you can adjust air pressure )between 55 and 75psi at the torch and that also depends on the amps you are cutting at.  50 amps and above likes 75 psi, 30 to 45 amps likes 60 to 70psi and below 30 amps try 40 to 55psi.   .www.georgesplasmacuttershop.comPlasma Cutter and Welder Sales and Repairs--Ebay storeTec.Mo. Dealer Consumables for the PT and IPT torch's
Reply:Originally Posted by mechanic416Yes  Mondo, the supply air can be as high as 135 to 150psi depending on the machine. But I have found that around 120psi seems to work best. Knowing that most air compressors drop to 90psi before restarting I tell my customers to run at least 1/2" main air line to get the volume needed. Because you need volume as well as pressure.      I have found that almost all the plasma cutters on the market will do the best cutting ( if you can adjust air pressure )between 55 and 75psi at the torch and that also depends on the amps you are cutting at.  50 amps and above likes 75 psi, 30 to 45 amps likes 60 to 70psi and below 30 amps try 40 to 55psi.  .