HT Electrodes

[Largemouthlou]

Jim, can a worn electrode still cause angularity in a cut even if there is a new nozzel installed ?

Seem to really be going through electrodes lately, one or 2 short cuts and then the anularity starts.. checked cut hieght and all, next will be the air supply,, But even if some moisture in air shouldn't I get more life out of them??

Been having a few faults when tourch was told to fire, actually had one electrode with black on the back of it (only one to date) see pics of front and back of it below.
HT1250 T80

[jimcolt]

A worn electrode will affect angularity because it can alter the torch to work distance. The plasma arc starts at the electrode....and ends at the plate. As the electrode wears...a pit develops that makes the arc attachment point further away from the plate...which makes the arc longer (higher arc voltage). If you have a height control that references arc voltage to control the distance to the plate....as the electrode wears the torch will start cutting closer and closer to the plate. If the electrode has a 1/32" pit depth, the torch will run 1/32 closer to the plate...and this will affect the bevel. A good operator will increase the arc voltage as the consumables wear to maintain the correct torch to work distance.

If you see black marks on the upper end of the electrode...either there is a lot of moisture /oil getting in your torch....and/or you have some damage occuring to the silver plated plunger inside your torch. There should be no signs of arcing on the plunger or the top of the electrode. Arcing here is 99% of the time caused by moisture/oil/particulates in your air system. If there is arcing here...expect poor cut quality and height control issues as well.

Moisture in the air:
-changes the physics inside the torch. The cutting process is designed to use clean, dry air...which is essentially 78% nitrogen and 22% oxygen. Add moisture (water) and it breaks down into oxygen and hydrogen inside the torch....the water usually carries some particulates and oil from the compressor. Now the arc acts totally differently than an air arc....cut quality gets worse and the electrode wears quickly.

-causes arcing inside the torch where arcing should not occur...such as at the plunger/electrode interface where the amperage from the power supply connects to the electrode.

-Changes the torch height/arc voltage relationship....expect the torch height to oscilate as slugs of moisture get into the arc.

Our tech service department (Hypertherm) sees a 50 to 60% increase in cut quality and consumable life related calls during humid summer months.

Hope this helps. Jim Colt

[Largemouthlou]

Jim, sorry for the delayed reply!! Yes your answer as always helps a lot!! It reminds me that I still have a whole lot to learn

Working on cleaning up the air and going to get a bigger compressor so I don't have to hook two in tandum to keep up with the cutting.. they are constantly running durring the cuts and I think that is causing extra moisture in the air.. I do have several motor guard filters and water seperators on them,, also adding a few more drops and traps on the air lines..

Gonna give your bud Bob Ballard a call this week as well.