Choosing between manual and mechanized plasma cutters

Using a beam of pressurized ionized gas (plasma) to pass through electrically conductive metals to cut them using thermal (heat) cutting process is the technology used in plasma cutters.

The pressurized gas is taut and released through a nozzle at high temperatures thus producing an electric arc in between the electrode(negative potential) of the cutter and the metal to be cut(positive potential).

The arc produced is hot enough to cut the metal beyond its melting point. A plasma arc is produced that melts and severs metals of varied thickness.

The molten metal is flushed through the kerf of the cut.

This is the working principle for both manual and mechanized plasma cutters.Metals conducting electricity like copper, iron, aluminium, cobalt, titanium, nickel alloys, stainless steel, carbon steel and magnesium can be cut using this method.​

Preferences-Manual or mechanized?​

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​The preference of the consumer depends upon the nature of work involved. Manual plasma cutters use a hand-held plasma torch for working. They are used by fabricating shops, construction work, and repair workshops, in ship building industry where the thickness of the metal is less and in metal art workshops.

​The power supply used in this method is lower in amperage when compared to mechanized plasma cutters. The maximum amperage suggested would not be more than 100 amperes considering safety issues. The least amperage on which it works is 7amperes.

Compressed shop air is usually used for ionized gas in this system. The input voltage can be in between 120 to 600 and therefore, it uses one-phase and three-phase power supply. With an improved technology, these are easily portable as they are less bulky than their older counterparts.

However, they lag back in their ability to cut metals of higher thickness. The maximum thickness of the metal they can cut with 100 ampere power is one and quarter inch at an estimated 20 inches per minute (IPM). When the power input increases, the cutting speed also increases, but, the quality of the cut suffers because of lower controlling ability.

Mechanized plasma cutters are larger in comparison to manual system of cutting as they are used along with cutting tables which either have a water table or a downdraft table with a supporting system that runs on different mechanisms like laser cutting, robotic cutting or punch press. This method also includes a CNC, torch height control (THC) and are therefore bulky and not portable.​

​Therefore, precise site planning has to be done before its installation in a place allowing for the various components to be set along with it.

Here, power supply that is used normally for oxygen cutting ranges between 100 amperes and 400 amperes. It ranges in between 100 and 6oo amperes for nitrogen cutting.

The power could be as low as 15 to 50 amps for some specific functions, but, the voltage input has to be in between 200v and 600v with a three phase power supply.​

Here, a variety of gases are used in the torch depending upon the nature of the metal that is being cut. Nitrogen gas, compressed air, oxygen, a mixture of argon/ hydrogen is used to deliver precision. Gas tanks are available for rent or purchase. For installing these gas tanks in the site, wiring and plumbing work should also be undertaken.

Therefore, if the nature of work is repetitive with absolute meticulousness or is for metals with greater thicknesses, mechanized system should be opted for.​

Cost involved in the setup:​

The cost involved in setting up a mechanized plasma cutter is significantly higher than manual plasma cutter. Also, the place for setting it up should be large enough to include storage options for gas tanks along with the main machine and its components.

There is a good deal of wiring and plumbing for the purposes of gas and coolant involved in the installation of a mechanized system.

Although a mechanized system will increase the life of the consumables and also increase cutting speed and efficiency, budget is an important consideration here.

Therefore, consider cost effectiveness along with quality of the work needed, the quantity to be produced, the speed required, cost involved in procuring materials, production cost and overheads and whether it is profitable to you before coming to a final choice.​

  • April 3, 2017
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