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Cutting-torchEquipment and MaterialsSOLUTIONS with Effective, Powerful AdviceCutting-torch, steel cutting, acetylene, propane, gasoline, hydrogen, demolition, scrap metal, rail cutting, underwater cutting, salvage, cutting torches, arc cutting, arc cutting torch, plasma arc cutting-torch, cutting tip, cutting kit, lasers, industrial lasers, CO2 laser, high power lasers, high power CO2 lasers, laser cutting, laser cutting machinery, cutting tips, cutting links, cutting problems needing answers: these are some of the items presented here for the benefit of interested readers. What is in here for me? Why a Cutting torch is a useful tool for metal construction preparation or for demolition? Because its principle of operation is simple, the technique can be learnt quickly, and its implementation is inexpensive if compared to mechanical cutting. Why some metals do not lend themselves to torch cutting? Because they are rich in elements that prevent ready oxidation.
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Several techniques, derived from those developed for welding, permit using a Cutting-torch for cutting metals, even of considerable thickness, as needed in preparation for further construction or, at the other end, for demolition. In a sense it could be said that the process of cutting is the exact opposite of welding: while welding consists in uniting together two separate metal pieces by progressive local melting, cutting is the progressive severing (in two or more sections) of one piece by local heating and burning away the metal. In this presentation the main aspects of metal cutting with a Cutting-torch will be addressed for three most important methods, that is cutting using oxyacetylene flame, arc-cutting (with its variant, namely plasma-cutting) and laser cutting. Tip!: Metal cutting by Cutting-torch is made possible by the tendency of certain metals to become readily oxidized under certain local conditions and burnt away by a powerful stream of oxygen gas. Torch-cutting. The Cutting-torch using the oxyacetylene flame is a special piece of equipment designed to implement a process whereby the chemical reaction of a pure oxygen stream with steel at elevated temperature produces local separation along the line of advancement. A small area must first be heated to the temperature of self sustained ignition (less than iron melting point), then a concentrated stream of high purity oxygen is directed on the same spot rapidly changing the metal into its oxides which melt and are removed by the force of the impinging stream along with any present molten metal drops. Tip!: For best quality cutting effects it is most important that the oxygen used be of high purity, at least 99.5%. It should be noted that not all materials are easily sectioned by these methods: outstanding in this group are aluminum and copper which cannot be cut. However, for most of the constructional steels, these may be the most economical ways to perform manual or automated cutting according to lines or patterns as needed. Special variations can be used with special powders for stainless steels or other difficult to cut materials. The Cutting-torch used is different from the customary welding torch (see Gas Welding Equipment): in one design the tip presents a crown of ports that supply the gas mixture employed to obtain the preheating flame, and a central channel through which the powerful pure oxygen stream is made to impinge on the heated spot to provide rapid oxidation and removal of oxides and metal drops. Once started the exothermic chemical reaction is self sustaining along the thickness of the metal (if the advancement speed of the Cutting-torch is not excessive), while the preheating flame is needed to bring new surfaces to ignition temperature. Critical to the success of the operation is the fact that iron oxides melt at lower temperature than the metal itself. If you are looking for Oxy-Acetylene Equipment including Welding and Cutting-torch you may wish to consider the following suggestions. At the time of this writing the products are sorted per increasing price. Compare descriptions to make sure that the product you consider meets your requirements. New Oxy/Acetylene cutting/welding torch kit
Victor Type Oxygen Acetylene Gas Cutting & Welding Torch Kit
Complete Light Duty Oxy-Acetylene Kit
Hobart Oxy-Acetylene Torch Kit #770282
Astro Pneumatic OxyAcetylene WeldingCutting Kit
Lincoln Electric (LE KH656) Medium Duty Oxygen-Acetylene Cutting, Welding,
Schumacher Medium Duty Oxy/Acetylene Cutting and Welding Kit
ProWeld Heavy-Duty Welding/Cutting Torch Set - Model# 7130BPW
Victor Journeyman II (510) Torch Kit For other products not listed above, print your request in the following Search Box and Go.
The Cutting-torch severed surface presents striations whose appearance indicates the quality of the cutting process. Ideally the surface should be as smooth as possible, with square edge and limited drag (curving in the direction opposite to advancement), absence of molten metal drops and minimum adhering slag. Accurate examination permits to improve the aspect through appropriate selection of parameters. The use of hydrogen instead of acetylene as a flammable gas in the Cutting-torch has found natural application in underwater cutting, where hydrogen can be compressed without danger to balance the hydrostatic pressure (which cannot be said of acetylene). The equipment is designed to provide an additional air bubble around the cutting tip, by supplying a continuous flow of compressed air. Tip!: A relatively new development, commercialized as a self contained unit, uses regular gasoline as fuel, with a special Cutting-torch and is claimed to have economic advantages over normal oxyacetylene cutting torch, within its range of applicability. ANSI/AWS C4.2:2002 ANSI/AWS F4.1-99 AWS FSW
Safety issues should be addressed by anyone involved in the practice of metal cutting using these Cutting-torch and other techniques. In another page on SAFETY we provided some useful links to information and codes pertaining to this important subject. The importance of thorough study and application of safe practices cannot be overemphasized. Arc-cutting. First arc Cutting-torch devices were developed without external compressed gas or air to assist with the disposal of molten metal produced by the heat of an electric arc. In modern operations, oxygen-arc cutting generally includes a special Cutting-torch with application of a jet of oxygen to promote cutting by the chemical reactions at the elevated temperature initiated by an arc between electrode and base metal. For oxidation resistant materials, cutting is obtained mainly by local melting with auxiliary means for helping with a fluxing action. The oxygen jet is sometimes conveyed through a hollow electrode in the Cutting-torch, covered with a special formulation of shielding material to aid in the disposal of molten metal, or as a parallel stream very near to the arc. Other applications, in steelmaking or foundry casting defect removal and conditioning, make use of compressed air instead of oxygen. The metallurgical effects on the cut surface are similar to those obtained during welding, and depend on the chemical composition of the base metal. Effects like hardening by quenching can be expected. Also sensitization of austenitic stainless steels can occur along and around the sectioned surface. A special development of Gas Metal Arc Welding (GMAW or Mig) By this method it was possible with the Cutting-torch to cut aluminum and stainless steel plates at high speed with a steel wire, using an inert shielding gas to protect the newly formed surfaces from contamination. The change from welding to cutting is only a matter of finding the proper parameters, wire diameter, wire feed speed and amperage. AWS A5.12/A5.12M-98 ANSI/AWS C5.3-2000 An Article on Air-Carbon Arc Cutting was published in the November 2005 Issue No. 27 of Practical Welding Letter. Click on PWL#027. Plasma Arc Cutting. Further development of the GMAW technique above brought about the process now known as Plasma Arc Cutting that use a specially made Cutting-torch. Among its advantages is instant startup without preheating, important for interrupted cutting. The process is versatile permitting cutting of all commercial metals. Its limitations, when compared to oxyacetylene cutting, are the limited thickness that can be cut, a wider kerf or gap produced, and the edge that can not be square to the surface. Plasma Arc Cutting (PAC) provides a stream of very hot plasma at 28000 oC (50000 oF) produced by a constricted arc between an electrode and the workpiece. The molten metal is removed by a continuous jet of high speed auxiliary gas provided by the Cutting-torch. By this process it is possible to cut at high speed any material conducting electricity. Current Cutting-torch equipment uses compressed air. In the past other gases were used, both inert and active (nitrogen, argon-hydrogen, oxygen etc.). Simplicity, efficiency and productivity (cutting speed) make Plasma Arc Cutting-torch an increasing popular choice.
If you are looking for a Plasma Cutting-torch, you can see a Data Summary Page for the following three Plasma Cutters you may wish to consider at
Hobart Airforce 250ci Light Weight Plasma Cutter With Air Compressor #500534 Cutting applicable to all electrically conductive metals,
The maximum thickness depends on current, speed, workmanship and required quality. Mild Steel Cutting Capability: Rated 1/8" (3.2 mm) - Quality 3/16" (4.2 mm).
Operating from 120 V outlet with 20 Amp single phase at rated output.
Rated output 12 A with 110 VDC, 35% Duty Cycle. Brochure downloadable from http://www.hobartwelders.com/products/pdf/spec_sheets/211798_AirForce250A.pdf For a complete description see the Owner's Guide downloadable from Hobart Airforce 400 Plasma Cutter #500474 Cutting applicable to all electrically conductive metals. Mild Steel Cutting Capability: Rated 3/8" (10 mm) - Quality 1/2" (13 mm). Operating from either 115 V (30 Amp) or 230 V (14 Amp) single phase at rated output or from engine driven welder with 240 VAC receptacle.
Rated output 27 A with 90 VDC, 35% Duty Cycle.
Brochure downloadable from
http://www.hobartwelders.com/products/pdf/spec_sheets/ For a complete description see the Owner's Guide downloadable from
Hobart Airforce 625 Plasma Cutter #500493 Suitable for light and heavy industrial users. Automated operations are also well within its range. Cutting applicable to all electrically conductive metals. The maximum thickness depends on current, speed, workmanship and required quality. Mild Steel Cutting Capability: Rated 1/2" (13 mm) - Quality 5/8" (16 mm).
Operating from either 208 V (33 Amp) or 230 V (30 Amp) single phase, or from engine-driven welders with a 240 V generator power outlet of 8 kW or more.
Rated output 40A at 140 VDC, 50% Duty Cycle.
Brochure downloadable from http://www.hobartwelders.com/products/pdf/spec_sheets/AirForce_625.pdf For a complete description see the Owner's Guide downloadable from A search page showing 7 ESAB plasma cutters with cutting capability on carbon steel up to 1/8 in. (3.18mm) thick for HandyPlasma 125 to 1-1/2 in. (38mm) manually for PowerCut® 1500 Plasmarc™ is available by clicking on
ESAB Cutters Tip!: This process permits cutting of materials not readily susceptible of being sectioned by other processes and, by virtue of its high speed attainable, has the added gain of very shallow influence on the properties, that is of a thin heat affected zone. ANSI/AWS C5.2-2001 ANSI/AWS C5.10/C5.10M-2003
A detailed Article on how to select your Plasma Cutter was published in the November 2003 issue #03 of Practical Welding Letter. To reach it, just click on PWL#003. An Article on Thermal Cutting Processes with secondary Water was published in the Issue 25 of September 2005 of Practical Welding Letter. To read the article Click on PWL#025.
To get all the issues of PWL as they are published, please subscribe. Plasmatron. A relatively new process, called Plasmatron, whose practical applications should be closely watched, results from an invention by Russian scientists. A special Cutting-torch, containing water, generates plasma through water steaming. An electric arc struck inside the torch, vaporizes the water and then ionizes the steam under self produced pressure to provide a plasma of 8000 0C that is used for cutting and related processes. The relatively simple equipment includes a special power supply of 2.5 kW and a water filled torch. There is no need for auxiliary gases or compressed air. It is claimed to cut steel up to about 10 mm and also any non combustible materials including stainless steel, high alloy steel, aluminum, titanium, brick, concrete and ceramic. Quality of cuts is said to be comparable to that of laser devices. No noxious gases are generated so that the process is ecologically safe even for operation in an enclosed space. A brief overview of laser processing and useful links were shown in High Energy Processes and the equipment was presented in High Energy Welding Equipment. Here we are going to introduce a few details on applications developed to cut through diverse materials, even nonmetals, using the powerful light beam called laser although not a Cutting-torch. This technique has known a large spread in various industries because of its natural adaptation to computer controlled automated systems. The extremely high power intensity at the focal spot can produce localized melting, vaporization and material removal in a very short time. By providing relative movement between the laser beam focus and the workpiece, the method permits rapid cutting of sheet metal in various shapes and dimensions and also drilling of precise holes. The method may make use of accessory gas (either inert or oxidizing) blowing activity to further speed up the removal of molten material. Most of the common metals, usually in sheet form, can be processed by laser cutting, except that the most reactive ones should be protected with a shielding atmosphere while locally at elevated temperature. Tip!: The heat affected zone near the laser cut is minimal in depth and usually of no consequence, except that for highly sophisticated applications even a very thin "recast layer" might be considered unacceptable. For a description of laser beam equipment and procedures, process basics, parameters and applications, see ANSI/AWS C7.2-98 We should add for completeness that holes drilling can be performed also using the electron beam, usually on dedicated machines: obviously these operate in vacuum, without assistance from gas streams. Waterjet Cutting An Article on Abrasive Water Jet Cutting was published (7) in Issue No. 47 of Practical Welding Letter for July 2007. Click on PWL#047 to read it.
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