20
(-)
Plasma cutting t orch
Work piece
Negative t erminal
Cutting m achine
R
Arc m aintenance cabl e
Electrode
S
Nozzle
Positive term inal
Work pie ce
7 - BASIC CUTTING TECHNIQUE
Note!
This section being general welding technique guide is for reference only.
Specific functions of your machine please refer to previous chapters.
Air plasma cutting is a cutting method using plasma arc thermal energy. When cutting, use
plasma arc to melt work piece, blow molten metal by jet stream to form cut. Air plasma cutting
can cut almost all metal materials, especially for high alloy steel and nonferrous metal which
cannot be cut by flame cutting. Advantages are as follows: highly centralized arc energy, good
stability, strong cutting ability; high cutting speed (3~5 times of gas cutting); low cost; arrow,
burnished, clean and almost vertical cutting edge; less work piece deformation.
Fig. 7-1: Cutting process
1.
Plasma arc type
According to power source connecting method, there are two kinds: transferred arc and non-
transferred arc.
(1)
Transferred type
Power source negative output terminal is connected with electrode; positive terminal is
connected with work piece. Plasma arc is generated between electrode and work piece. First,
it needs to ignite plasma flame flow between electrode and nozzle, and plasma airflow makes
plasma flame flow contact with work piece to form plasma arc. Plasma arc formed by this
transferred method is called transferred arc. Transferred arc can reduce nozzle burning
caused by arc starting or liquid metal spatter.
Fig. 7-2: Transferred type
