PLASMA CUTTER

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PLASMA CUTTER

• WELDING
• JANUARY 2006

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PLASMA CUTTER

• Industry standards to replace Oxy-Acetylene
  torches.
• Also a cleaner cut.
• Uses electricity and compress air. The
  electricity is used for cutting and the air blows
  away the sparks and melted metal.
• Use Safety glasses to protect your eyes from the
  rays coming off the machine
• Make sure air lines are water free. Plasma
  cutter hates water.
• The Plasma cutter should cut up to 1/2" thick
  metal.

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A. Plasma Gas Flow.

• Plasma is a gas which has been heated to an
  extremely high temperature and ionized so that it
  becomes electrically conductive.
• The plasma arc cutting and gouging processes use
  this plasma to transfer an electrical arc to the
  workplace. The metal to be cut or removed is
  melted by the heat of the arc and then blown
  away.
• While the goal of plasma arc cutting is
  separation of the materials, plasma arc gouging
  is used to remove metals to a controlled depth
  and width.

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Plasma Basics

• Plasma looks and behaves like a high-temperature
  gas, but with an important difference it
  conducts electricity and cuts any electrically
  conductive metal.
• The plasma arc results from electrically heating
  a gas, typically air, to a very high temperature.
  This ionizes its atoms and enables them to
  conduct electricity.
• A plasma arc torch uses a "swirl ring" that
  spins the gas around an electrode. The gas is
  heated in the chamber between the electrode and
  torch tip, ionizing the gas and creating plasma.
  This causes the plasma gas to greatly expand in
  volume and pressure. The small, narrow opening of
  the torch tip constricts the plasma and
  accelerates it toward the work piece at very high
  speeds (20,000 ft./s) and temperatures (up to
  30,000 F).
• The high-intensity plasma jet melts a very
  localized area.
• The force of the jet (or arc) pushes through the
  work piece and removes the molten metal.
• This jet easily cuts through metals with poor
  heat conductivity (stainless steel) or excellent
  conductivity (aluminum).
• The flame created by an oxy-fuel torch lacks
  plasma's concentration and cuts stainless steel
  or aluminum so poorly (excess warping or dross)
  that professionals don't bother to use it they
  consider plasma arc cutting the standard process
  for these metals.

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• Cool gas enters Zone B, where a pilot arc between
  the electrode and the torch tip heats and ionizes
  the gas.
• The main cutting arc then transfers to the work
  piece through the column of plasma gas in Zone C
• By forcing the plasma gas and electric arc
  through a small orifice, the torch delivers a
  high concentration of heat to a small area. The
  stiff, constrict plasma arc is shown in Zone C.
  Direct current (DC) straight polarity is used for
  plasma cutting, as shown in the illustration.
• Zone A channels a secondary gas that cools the
  torch. This gas also assists the high velocity
  plasma gas in blowing the molten metal out of the
  cut allowing for a fast, slag free cut.

B
B
A
C
C
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Operation of Plasma Cutter

• Plug in plasma cutter to 220 volt circuit. (same
  as the welder)
• Connect air line--check gages to make sure you
  have about 60 of line pressure
• Adjust heat knob to the correct setting for the
  metal. The higher the setting the more heat.
• Connect ground clamp to work.
• Turn on--Red light should appear when ready.
• With eye protection "hit" the black top knob and
  red bottom knob on handle.
• Make sure your are at the right distance with
  handle
• Cut.

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 Problems Using the Plasma Cutter

• Make sure ground clamp is connected to metal
• You have 60 of air pressure
• If plasma cutter does not work--check and change
  cutting tip and nozzle.
• Check to make sure there is no water in the line
• Check for voltage drop.

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