03 Introduction To Plasma - ESAB CIGWELD CutSkill 60 Operating Manual

CutSkill 60
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 conductive. The plasma arc
cutting process uses 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.
In a Plasma Cutting Torch a cool gas enters Zone B,
where an 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 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.
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Power
Supply
+
C
Figure 2T-2: Typical Torch Head Detail
INTRODUCTION
OPERATING MANUAL
B. Gas Distribution
C. Main Cutting Arc
A
B
Workpiece
A-00002
2T-2
The single gas used is internally split into plasma
and secondary 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.
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 con-
nected to the workpiece via the work cable.
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