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This article is written in British English, which has its own spelling conventions (colour, travelled, centre, defence, artefact, analyse) and some terms that are used in it may be different or absent from other varieties of English. According to the relevant style guide, this should not be changed without broad consensus. |
The transistors used were initially MOSFETs, but are now increasingly using IGBTs. With paralleled MOSFETs, if one of the transistors activates prematurely it can lead to a cascading failure of one quarter of the inverter. A later invention, IGBTs, are not as subject to this failure mode. IGBTs can be generally found in high current machines where it is not possible to parallel sufficient MOSFET transistors.
It would be awesome to have a picture of plasma cutting in action taken through welding glass, showing what the operator sees. ― BenFrantzDale 04:02, 10 February 2006 (UTC)
Actually you see very little. The fire blows right through the material and there is near nothing to see on the front side---but a great blast of fire on the back side.
Photographing the welding /cutting in action is very difficult because of the lighting issues but I'll look for a photo of some cutting that is completed it is interesting as well. —Preceding unsigned comment added by Rvannatta ( talk • contribs) 07:22, August 26, 2007 (UTC)
jlj.ko The article implies that the metal is turned to plasma. From watching the process it seems much more plausible that the metal is primarily liquified (and maybe also vaporized) but that it is primarily the inert gas which is the plasma. ― BenFrantzDale 05:32, 14 February 2006 (UTC)
In plasma cutting process, metal is often "burned" with oxygen. For example when cutting mild steel, oxygen is used as main plasma gas. Oxygen react with steel - steel simply burns and changes to dust of oxides. [1] 188.167.228.35 ( talk) 06:05, 2 July 2016 (UTC)mato
References
I'm skeptical of the 15,000 km/h flow rate quoted here and in some of the links. At very least it seems misleading. My sense is that one molecule of inert gas doesn't stay plasma for very long. The gas jet without plasma is fast, but ridiculously fast. My hunch, then, is that the heated gas and plasma may be ridiculously fast, but that the mass flow rate doesn't change when the arc is on versus off. In other words, if you heat flowing gas from ~300 K to ~30,000 K, it will move 100 times faster. ― BenFrantzDale 04:32, 16 February 2006 (UTC)
At 15,000 km/h, a flow with a 1 cm2 cross section would go through 14.7 cubic feet per second (i.e., you could empty a scuba tank in 5.4 seconds). ― BenFrantzDale 04:32, 16 February 2006 (UTC)
12 cm cross section? Most nozzles are .020-.090 inches (~.0026 cm2 to .041 cm2) Might yield more realistic calculations, plus the whole temperature thing. 71.252.248.7 03:50, 1 September 2006 (UTC)
It's not a pure plasma. Only a portion of the gas passing through the nozzle is ionized. The flow rate DOES change, as the plasma reacts to the electric field in the torch and on the workpiece. - Toastydeath 04:24, 5 December 2006 (UTC)
Can someone explain the following two apparently conflicting statements in the article: 1 "The HF Contact type typically found in budget machines uses a high-frequency, high-voltage spark to ionise the air through the torch head and initiate an arc. These require the torch to be in contact with the job material when starting, and so are not suitable for applications involving CNC cutting." 2 "Plasma cutters working near sensitive electronics, such as CNC hardware or computers, use the contact start method. The nozzle and electrode are in contact. The nozzle is the cathode, and the electrode is the anode. When the plasma gas begins to flow, the nozzle is blown forward." JSM Saudi Arabia —Preceding unsigned comment added by 212.118.128.246 ( talk) 11:20, 4 November 2009 (UTC)
I use two hand held plasma torches and an automated CNC plasma in my shop. I've never seen a hand held plasma torch that can cut 2" thick steel plate. My cutting table is 6' x 12' and uses a Hypertherm 130HSD. The dimensions on this unit are about 4' x 4' and it weighs more than 300', the maximum thickness it can cut with edge start is 1 1/2" steel. This Wikipedia article has already been disseminated throughout the internet claiming that a hand held plasma can usually cut 2" thick steel, and a automated table system can usually cut 6" thick steel. I believe the author confused plasma cutting with acetylene cutting. —Preceding unsigned comment added by 216.212.106.154 ( talk) 20:04, 3 February 2011 (UTC)
Not correct:
- Mechanised plasma http://www.kjellberg.de/Plasma-Cutting/Products/CNC-and-mechanised/FineFocus-series/FineFocus-1600.html cuts trough 160mm.
- Handheld plasma http://awp-p.com/awp2/pdf/prospekt_pas25-70w_en.pdf cuts trough 70mm.
You can actually cut trough any thickness with custom made torches. A FineFocus 1600 is actually two FineFocus 800 added together, if you add more you can increse the amperage and thus the thickness you can cut. Torches and consumables can be custom made for higher amperage. All you have to do is increase the cooling flow and increase diameter of the hole in the nozzle and shield. 195.26.2.117 ( talk) 10:57, 25 February 2011 (UTC)
This article states that a hand held plasma can USUALLY cut 2" thick steel. And that a typical mechanized system can cut through 6" steel. What I am saying is that neither of those scenarios are usual or typical from the myriad of shops I've worked in. The handheld torch that cuts through 2" steel would be unwieldy. We can talk about custom plasma torches all day, but that is not how the article is worded. Usually means commonly and a hand held that cuts 2" steel is not common. The link you provided for the handheld that cuts 70mm is not working, so I cannot verify it. I am only talking from years of personal experience, however important that may be for Wikipedia. — Preceding unsigned comment added by 216.212.106.154 ( talk) 18:52, 2 June 2011 (UTC)
Please post pictures or video of a hand held plasma torch cutting 2" thick steel. Also post some CNC plasmas cutting 6" thick steel. If it is typical and usual, you should have no problem locating some photographs.. — Preceding
unsigned comment added by
64.139.81.85 (
talk) 23:22, 16 June 2011 (UTC)
The article at present claims that the eye, and face, safety hazard for plasma cutting is the same as for arc welding. This is unsourced, and plasma equipment manufacturers do not claim this. The goggle tint is lighter and there is no requirement for a face shield. No doubt someone will now find a "source" in Google that the KillerTron 2000 50MW plasma-cutting deathray requires a tinfoil hat to be worn at all time. Yet in the general case, and where encylopedic coverage is so needed, for the type of hand-held plasma cutters used in industry it is wrong to describe them as equivalent to arc welding protection. Andy Dingley ( talk) 19:35, 15 May 2016 (UTC)
Anyone knows why they were so expensive just few years ago, and are much cheaper now? Nestashi ( talk) 16:36, 15 September 2019 (UTC)
This article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||
|
This article is written in British English, which has its own spelling conventions (colour, travelled, centre, defence, artefact, analyse) and some terms that are used in it may be different or absent from other varieties of English. According to the relevant style guide, this should not be changed without broad consensus. |
The transistors used were initially MOSFETs, but are now increasingly using IGBTs. With paralleled MOSFETs, if one of the transistors activates prematurely it can lead to a cascading failure of one quarter of the inverter. A later invention, IGBTs, are not as subject to this failure mode. IGBTs can be generally found in high current machines where it is not possible to parallel sufficient MOSFET transistors.
It would be awesome to have a picture of plasma cutting in action taken through welding glass, showing what the operator sees. ― BenFrantzDale 04:02, 10 February 2006 (UTC)
Actually you see very little. The fire blows right through the material and there is near nothing to see on the front side---but a great blast of fire on the back side.
Photographing the welding /cutting in action is very difficult because of the lighting issues but I'll look for a photo of some cutting that is completed it is interesting as well. —Preceding unsigned comment added by Rvannatta ( talk • contribs) 07:22, August 26, 2007 (UTC)
jlj.ko The article implies that the metal is turned to plasma. From watching the process it seems much more plausible that the metal is primarily liquified (and maybe also vaporized) but that it is primarily the inert gas which is the plasma. ― BenFrantzDale 05:32, 14 February 2006 (UTC)
In plasma cutting process, metal is often "burned" with oxygen. For example when cutting mild steel, oxygen is used as main plasma gas. Oxygen react with steel - steel simply burns and changes to dust of oxides. [1] 188.167.228.35 ( talk) 06:05, 2 July 2016 (UTC)mato
References
I'm skeptical of the 15,000 km/h flow rate quoted here and in some of the links. At very least it seems misleading. My sense is that one molecule of inert gas doesn't stay plasma for very long. The gas jet without plasma is fast, but ridiculously fast. My hunch, then, is that the heated gas and plasma may be ridiculously fast, but that the mass flow rate doesn't change when the arc is on versus off. In other words, if you heat flowing gas from ~300 K to ~30,000 K, it will move 100 times faster. ― BenFrantzDale 04:32, 16 February 2006 (UTC)
At 15,000 km/h, a flow with a 1 cm2 cross section would go through 14.7 cubic feet per second (i.e., you could empty a scuba tank in 5.4 seconds). ― BenFrantzDale 04:32, 16 February 2006 (UTC)
12 cm cross section? Most nozzles are .020-.090 inches (~.0026 cm2 to .041 cm2) Might yield more realistic calculations, plus the whole temperature thing. 71.252.248.7 03:50, 1 September 2006 (UTC)
It's not a pure plasma. Only a portion of the gas passing through the nozzle is ionized. The flow rate DOES change, as the plasma reacts to the electric field in the torch and on the workpiece. - Toastydeath 04:24, 5 December 2006 (UTC)
Can someone explain the following two apparently conflicting statements in the article: 1 "The HF Contact type typically found in budget machines uses a high-frequency, high-voltage spark to ionise the air through the torch head and initiate an arc. These require the torch to be in contact with the job material when starting, and so are not suitable for applications involving CNC cutting." 2 "Plasma cutters working near sensitive electronics, such as CNC hardware or computers, use the contact start method. The nozzle and electrode are in contact. The nozzle is the cathode, and the electrode is the anode. When the plasma gas begins to flow, the nozzle is blown forward." JSM Saudi Arabia —Preceding unsigned comment added by 212.118.128.246 ( talk) 11:20, 4 November 2009 (UTC)
I use two hand held plasma torches and an automated CNC plasma in my shop. I've never seen a hand held plasma torch that can cut 2" thick steel plate. My cutting table is 6' x 12' and uses a Hypertherm 130HSD. The dimensions on this unit are about 4' x 4' and it weighs more than 300', the maximum thickness it can cut with edge start is 1 1/2" steel. This Wikipedia article has already been disseminated throughout the internet claiming that a hand held plasma can usually cut 2" thick steel, and a automated table system can usually cut 6" thick steel. I believe the author confused plasma cutting with acetylene cutting. —Preceding unsigned comment added by 216.212.106.154 ( talk) 20:04, 3 February 2011 (UTC)
Not correct:
- Mechanised plasma http://www.kjellberg.de/Plasma-Cutting/Products/CNC-and-mechanised/FineFocus-series/FineFocus-1600.html cuts trough 160mm.
- Handheld plasma http://awp-p.com/awp2/pdf/prospekt_pas25-70w_en.pdf cuts trough 70mm.
You can actually cut trough any thickness with custom made torches. A FineFocus 1600 is actually two FineFocus 800 added together, if you add more you can increse the amperage and thus the thickness you can cut. Torches and consumables can be custom made for higher amperage. All you have to do is increase the cooling flow and increase diameter of the hole in the nozzle and shield. 195.26.2.117 ( talk) 10:57, 25 February 2011 (UTC)
This article states that a hand held plasma can USUALLY cut 2" thick steel. And that a typical mechanized system can cut through 6" steel. What I am saying is that neither of those scenarios are usual or typical from the myriad of shops I've worked in. The handheld torch that cuts through 2" steel would be unwieldy. We can talk about custom plasma torches all day, but that is not how the article is worded. Usually means commonly and a hand held that cuts 2" steel is not common. The link you provided for the handheld that cuts 70mm is not working, so I cannot verify it. I am only talking from years of personal experience, however important that may be for Wikipedia. — Preceding unsigned comment added by 216.212.106.154 ( talk) 18:52, 2 June 2011 (UTC)
Please post pictures or video of a hand held plasma torch cutting 2" thick steel. Also post some CNC plasmas cutting 6" thick steel. If it is typical and usual, you should have no problem locating some photographs.. — Preceding
unsigned comment added by
64.139.81.85 (
talk) 23:22, 16 June 2011 (UTC)
The article at present claims that the eye, and face, safety hazard for plasma cutting is the same as for arc welding. This is unsourced, and plasma equipment manufacturers do not claim this. The goggle tint is lighter and there is no requirement for a face shield. No doubt someone will now find a "source" in Google that the KillerTron 2000 50MW plasma-cutting deathray requires a tinfoil hat to be worn at all time. Yet in the general case, and where encylopedic coverage is so needed, for the type of hand-held plasma cutters used in industry it is wrong to describe them as equivalent to arc welding protection. Andy Dingley ( talk) 19:35, 15 May 2016 (UTC)
Anyone knows why they were so expensive just few years ago, and are much cheaper now? Nestashi ( talk) 16:36, 15 September 2019 (UTC)