Thermal Cutting is used for the shape cutting of steels and other metals that can be burned or displaced via thermal methods such as Steel, Stainless Steels, Copper, Brass.  At Southern Fabricating Machinery Sales, Inc. we offer a wide variety of Plasma, Oxy Fuel and Hi-Definition Plasma and Burning Systems.  These thermal or “burning” machines are probably one of the oldest forms of  metal shape cutting, short of the physical hammering/sawing/hacking methods. Either an Oxy-Fuel (typically O2 mixed with Propane) mix or the newer Plasma Technology is employed to burn/melt materials up to and even over 6” thick. This machining method is a thermal method and thus the material being cut must yield to high temperatures. The machines' motion system is controlled via a computer controller or CNC however older machines utilized an optical tracer eye and some even used physical template tracer methods. Machines can be configured with one or more of either Oxy/Fuel or Plasma and can even include a combination of both methods for the most flexibility in shape cutting.

The two types of thermal cutting are Oxy/Fuel and Plasma with one sub category of “Hi-Definition” or “Fine Plasma”  Both process are described in detail below.

Oxy/Fuel – Torches, much like a welders oxy/acetylene torch, are used to mix gases for high temperature cutting. These gases can be any flammable gas but is typically a mixture of Propane to burn and Oxygen to intensify.  This method of thermal cutting is typically the most efficient shape cutting method however it is much slower than plasma cutting and is typically of very little use on materials thinner than 1/2” - 3/8” due the high heat resulting in warpage of the material  Oxy/Fuel is best applied to steels 1/2” and thicker.

Plasma – In the 1960's scientists discovered that by increasing the speed of gases coming out of a small hole they could force a very high and direct thermal process called PLASMA.  This process allowed parts that were thermally cut to now have almost “saw like” finishes versus the older molten rough edges that Oxy Acetylene provided.  The plasma torch is a specially designed torch that forces gases through an extremely small hole where a current of power is applied and thus the plasma process begins.  Plasma requires large amounts of high pressure clean dry air and oxygen for the process to work correctly and the consumables to have an acceptable life.   Plasma cutters are available in both hand held and machine mounted power supply.

Ranges: Typically plasma power sources are rated at ½ their amperage for the overall cutting capacity in steels.  As an example a 100 AMP power supply is typically rated to both pierce and cut 1/2” thick of steel and can cut from an existing hole or part edge up to 5/8” – 3/4” .  Whereas a 200Amp Plasma Power Source is rated to both pierce and cut up to 1” thick of steel continuously and can be used from a start hole at thicknesses up to 1-7/8”

“Hi Definition / Fine Plasma” – In the 1990's further development of electronics and the plasma process resulted in very finely tuned power sources and newer precise cutting torches.  These systems are only found on machinery and are not available for handheld applications as to achieve the best results the stand – off distance and traverse speed must be greatly controlled.  These power sources can provide the best surface finishes, part accuracies and detail but must be used in conjunction with an accurate machine to produce an accurate part.

Pick a Table
Thermal processing requires a table to support the material resist the high temperature and to absorb or ventilate the smoke and fumes from the cutting process. In most cases the table is not part of the initial system quoted and must be calculated for. The tables are very commonly fabricated right onsite by the burning tabel purchaser in order to fit the custom configuration they desire. There are several popular options for tables but all must be conductive to allow for the Plasma Process (if used) and they are described as follows: 

Material Supports: This can be anything that is non-flammable that supports the weight of the workpiece. Metal Saw Horses, Pillars etc can all be used

Dry Table: This is a table manufactured for the explicit use of thermal cutting and is typically fashioned high enough off of the floor to allow for the cleaning of slag and other molten material from underneath the table. This table provides no fume or smoke control method and is best suited for out-door applications.

Water Table: Applicable only to plasma cutting this is best described as a water tank. This table is typically made of replaceable slats of steel supported on each edge of a tank filled with water.  The material surface is typically below the water line which somewhat controls the smoke, dust and fumes associated with plasma cutting. The water does cause some problems with the molten slag quickly cooling and re-adhering to the material as well as rust and cleanup problems.

Downdraft Table: This table is similar to the water table described above however instead of being filled with water the table or tank is exhausted by high capacity fans to pull the smoke and fumes from the cutting process down into the tank and ducted to either outside of the machining area or through a dust collector.  This type of table can have ducted “zones” in the table which are controlled by the location of the cutting torch which improves the efficiency of the table greatly.

At Southern Fabricating Machinery Sales we are not only experts in Plasma and Oxy/Fuel cutting technologies, but also in the newer Laser Cutting technology and other shape cutting processes such as Waterjet and CNC Punching. We can not only offer you the right system for your application, but for your budget as well. Call us today at 813-444-4555 or visit us online at