Plasma cutting

[Snaker]

I recently got myself a Chicago Electric Model 95136. I am happy with its performance and give it a thumbs up for the lighter duty projects that I do.

My question is about the proper way to cut with it, always dragging it making contact with the material or keeping a gap from the material. It is a design that produces a pilot arc without touching the material.
The manual states in part:"
12. This unit provides a pilot arc, so the torch does not need to contact the workpiece before the cutting arc ignites.
14. Bring the Electrode of the torch close to the starting point of the cut. The working indicator light will come on.
15. Slowly move the torch at a slight angle along the cutting line with the torch tip trailing."

I occasionally use a Hypertherm Powermax 85 at work and always make contact with the material as told although I have never seen a manual for that machine.

I have been trying both ways with mine without noticing much difference on the cut but the tip is wearing fairly fast. Will the tip last longer by keeping it off the material?

 

[FredH]

My brother has a pilot arc plasma also , not that brand but another . His has a " Standoff " attached to the outer cup that keeps it a set distance off the work piece , and I do think it will wear out electrodes faster by constantly touching , at least mine which is not a pilot arc type will .

Fred H.

 

[Ken45101]

Hypertherm has both shielded and unshielded consumables. "With unshielded consumables, maintain an approximate .08 inch standoff." When using the normal shielded consumables "drag the nozzle lightly across the workpiece to proceed with the cut." (From the Hypertherm Powermax 45 manual.)

I just got the Hypertherm 45 a couple of days ago. Very impressive

Ken

 

[J_J]

Lincoln has a drag nozzle to add on for drag. It is made out of copper, so it will also wear.

You would think a drag tip would be made of ceramic.

There is also this which will keep the tip off the surface.

http://www.flangewizard.com/products119.html

 

[longevity]

Stand offs do help non-drag tips. Generally, it prevents slag from attaching on to the consumable and helps prevent the deterioration of the consumable.

The recommended distance of cutting is 1/16th or 1/8th for LONGEVITY plasma cutters. I am sure its the same for other brands.

You can also take a steel brush and brush off the tip after cutting to get rid of the slag on there as well to help prolong the consumables life. On some of our torches, like the pt-31, you can flip the electrode inside as well and pro-long your life of the consumables.

Hope that helps..

Simon

 

[jimcolt]

All of the current Hypertherm air plasma systems are designed for dragging directly on the plate...at up to 200 amps (2 inch thickness). Shield technology, invented by Hypertherm to increase torch nozzle life, uses an electrically isolated copper shield in front of the nozzle. This shield provides for a good edge for template or straightedge guidance, and eliminates the double arcing that occurs with any unshielded plasma torch design.

Further, the same shield technology allows machine mounted torches to pierce thicker without blowback spatter affecting nozzle (tip) life. The latest shield designs on the newer powermax45, 65 and 85 systems use the shield to provide an extra squeeze (known from the patent as "conical flow") which provides squarer edges, faster speeds and even longer nozzle life.

Torch technology is perhaps more important in the plasma cutting process than the power supply.


Jim Colt

 

[Snaker]

Thanks for the responses. I was shown a way to download the Hypertherm operators manual. I see that the type of nozzle dictates: Shielded/ make contact, non-shielded/ keep a gap.
I just don't see that discussed in the Chicago Electric manual so I don't know if I have a shielded or non-shielded nozzle on mine. Is it a certain shape or design of the nozzle that would dictate?

 

[J_J]

jimcolt, You said this: uses an electrically isolated copper shield in front of the nozzle.

Lincoln has been using that isolated copper shield for a while now.

Did they borrow that idea from Hypertherm?

I use it on my Lincoln Pro-Cut 55, but they don't recommend it on the Pro-Cut 25 that I have also.

 

[jimcolt]

The Hypertherm shield patents (for isolation) expired a few years ago....T-D, Lincoln, Miller all use their own versions of the technology. The newest Hypertherm's have a newer technology called "conical flow" which uses the isolated shield to add a secondary squeeze to the arc...increasing energy density without sacrificing consumable life. Squarer, cleaner and faster cutting at the same power levels as others.....this cannot be copied for quite a few years without infringing on the patent.

Most of the low cost import plasma systems use older technology torches....such as copies of an old Esab (PT31) torch design....as well as some rough copies of 20 year old torches with blowback starting (non high frequency) that are produced by an italian torch producer, Trafimet. None that I have seen are shielded...rather, they use a wire standoff device so that the nozzle does not contact the plate.

The shield technology is not used on the lowest powered torches (like the Lincoln 25 or the Hypertherm Powermax30) as it requires a longer arc (higher arc voltage) to work well.....these low powered units are designed to operate on 120 VAC current....and are drawing all the power just to operate. The shield would make their performance a bit more sluggish!



Jim Colt

jimcolt, You said this: uses an electrically isolated copper shield in front of the nozzle.

Lincoln has been using that isolated copper shield for a while now.

Did they borrow that idea from Hypertherm?

I use it on my Lincoln Pro-Cut 55, but they don't recommend it on the Pro-Cut 25 that I have also.

 

[Haywire]

Jim, could a less expensive power supply be upgraded with a higher end torch?