CUTMASTER 10MM, 12MM INTRODUCTION
Introduction 2T-2 Manual 0-5230
2T.03 Introduction to Plasma
A. Plasma Gas Flow
Plasma is a gas which has been heated to an extremely high
temperature and ionized so that it becomes electrically con-
ductive. The plasma arc cutting and gouging processes use
this plasma to transfer an electrical arc to the workpiece. 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 material,
plasma arc gouging is used to remove metals to a controlled
depth and width.
In a Plasma Cutting Torch a cool gas enters Zone B, where a
arc between the electrode and the torch tip heats and ionizes
the gas. The main cutting arc then transfers to the workpiece
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, constricted plasma arc is shown in Zone
C. Direct current (DC) straight polarity is used for plasma cut-
ting, 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.
A-00002
Workpiece
Power
Supply
+
_
C
B
A
Typical Torch Head Detail
B. Gas Distribution
The single gas used is internally split into plasma and second-
ary gases.
The plasma gas flows into the torch through the negative lead,
through the starter cartridge, around the electrode, and out
through the tip orifice.
The secondary gas flows down around the outside of the torch
starter cartridge, and out between the tip and shield cup around
the plasma arc.
C. Pilot Arc
When the torch is started a pilot arc is established between the
electrode and cutting tip. This pilot arc creates a path for the
main arc to transfer to the work.
D. Main Cutting Arc
DC power is also used for the main cutting arc. The negative
output is connected to the torch electrode through the torch
lead. The positive output is connected to the workpiece via the
work cable and to the torch through a pilot wire.
E. Parts - In - Place (PIP)
The torch includes a 'Parts - In - Place' (PIP) circuit. When
the shield cup is properly installed, it closes a switch. The
torch will not operate if this switch is open.
To Next Page
Loading...
Need help?
General
