Plasma cutting
Plasma cutting is often used in fabrication shops, automotive repair and restoration, industrial construction, and salvage and scrapping operations.
This is accomplished by a compressed gas (oxygen, air, inert and others depending on material being cut) which is blown through a focused nozzle at high speed toward the workpiece.
As electricity from the cutter torch travels down this plasma it delivers sufficient heat to melt through the workpiece.
At the same time, much of the high-velocity plasma and compressed gas blow the hot molten metal away, thereby separating, i.e. cutting through, the workpiece.
When the control system senses current flowing from the electrode to the work, it cuts the electrical connection to the nozzle.
Early plasma cutters were large, somewhat slow and expensive and, therefore, tended to be dedicated to repeating cutting patterns in a "mass production" mode.
"[3] Lincoln Electric, a manufacturer of plasma cutting equipment, says, "Typically a darkness shade of #7 to #9 is acceptable."
Longevity Global, Inc., another manufacturer, offers this more specific table for eye protection for plasma arc cutting at lower amperages:[citation needed]
Leather gloves, an apron and a jacket are also recommended to prevent burns from sparks and hot metal.
Sparks and hot metal from a plasma cutter can quickly cause fires if they are not isolated from flammable objects.
This method has a number of disadvantages, including risk of electrocution, difficulty of repair, spark gap maintenance, and the large amount of radio frequency emissions.
[6] Plasma cutters working near sensitive electronics, such as CNC hardware or computers, start the pilot arc by other means.
Higher switching frequencies allow smaller transformers resulting in overall size and weight reduction.
CNC tables allow a computer to control the torch head producing clean sharp cuts.
Modern CNC plasma equipment is capable of multi-axis cutting of thick material, allowing opportunities for complex welding seams that are not possible otherwise.
When the weld preparation is applied during the CNC plasma cutting process, secondary operations such as grinding or machining can be avoided,[citation needed] reducing cost.
The plasma cutting head usually remains stationary whilst the workpiece is fed through, and rotated around its longitudinal axis.
Several manufacturers have combined precision CNC control with these torches to allow fabricators to produce parts that require little or no finishing.
