PRO-POINT ARC 170 Manuel D'utilisation page 29

V1.0 ARC 170 DUAL VOLTAGE ARC/TIG WELDER 8611295
keep the correct arc length at all times. Excessive travel speeds
lead to poor fusion, lack of penetration etc., while too slow a
rate of travel will frequently lead to arc instability, slag
inclusions and poor mechanical properties.
MATERIAL AND JOINT PREPARATION
The material to be welded should be clean and free of any
moisture, paint, oil, grease, mill scale, rust or any other material
that will hinder the arc and contaminate the weld material.
Joint preparation will depend on the method used include
sawing, punching, shearing, machining, flame cutting and
others. In all cases edges should be clean and free of any
contaminates. The type of joint will be determined by the
chosen application.
DC TIG WELDING
The DC power source uses what is known as DC (direct current)
in which the main electrical component known as electrons flow
in only one direction from the negative pole (terminal) to the
positive pole (terminal). In the DC
electrical circuit there is an electrical
principle at work which should always
be taken into account when using any
DC circuit. With a DC circuit 70% of the
energy (heat) is always on the positive
side (Fig. 13). This needs to be
understood because it determines what
terminal the TIG torch will be connected
to (this rule applies to all the other
forms of DC welding as well).
Fig. 13
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