PRO-POINT MIG-ARC-TIG 145A Manuel De L'utilisateur page 23

V1.0
WIRE TYPES AND SIZES
Use the correct wire type for
the base metal being welded.
Use stainless steel or silicon
bronze wire for stainless steel,
aluminum wires for aluminum
and steel wires for steel.
Use a smaller diameter wire
for thin base metals. For
thicker materials use a larger
wire diameter and larger
machine, check the
recommended welding
capability of your machine.
As a guide, refer to the
Welding Wire Thickness Chart
in Table 3.
GAS SELECTION
The purpose of the gas in the
MIG process is to protect/shield
the wire, the arc and the molten weld metal from the atmosphere. Most metals when heated to a
molten state will react with the air. Without the protection of the shielding gas, the weld produced
would contain defects like porosity, lack of fusion and slag inclusions. Additionally some of the gas
becomes ionized (electrically charged) and helps the current flow smoothly.
The correct gas flow is also very important in protecting the welding zone from the atmosphere. Too
low of a flow will give inadequate coverage and result in weld defects and unstable arc conditions.
Too high of a flow can cause air to be drawn into the gas column and contaminate the weld zone.
USE THE CORRECT SHIELDING GAS
Co2 is good for steel and offers good penetration characteristics;
the weld profile is narrower and slightly raised than the weld profile
obtained from an Argon/Co2 mixed gas. Argon/Co2 mix gas offers
better weld ability for thin metals and has a wider range of setting
tolerance on the machine. Argon 75%/Co2 25% is a good all round
mix suitable for most applications (Fig. 46).
DC TIG WELDING
WARNING! Disconnect the Electrode Holder cable from the machine before using TIG function. If
the cable is not disconnected, welding voltage is present and can cause arcing or flash.
The power source uses direct current (DC). 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. 47). 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).
DC TIG welding is a process in which an arc is
struck between a TUNGSTEN electrode and the
metal workpiece. The weld area is shielded by an
inert gas flow to prevent contamination of the
tungsten, molten pool and weld area (Fig. 48).
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145A MULTI-PROCESS MIG-ARC-TIG WELDER
WELDING WIRE THICKNESS CHART
MATERIAL
THICKNESS
24 Gauge (.60 mm)
22 Gauge (.75 mm)
20 Gauge (.90 mm)
18 Gauge (1.0 mm)
16 Gauge (1.2 mm)
14 Gauge (1.9 mm)
0.118 in. / 3 mm
0.196 in. / 5 mm
0.236 in. / 6 mm
0.314 in. / 8 mm
0.393 in. / 10 mm
0.472 in. / 12 mm
RECOMMENDED WIRE DIAMETERS
MIG SOLID WIRE
0.025 in. 0.030 in. 0.035 in. 0.040 in. 0.30 in. 0.035 in. 0.045 in.
For material thickness of 0.196 in. (5.0 mm) and greater, multi-pass
runs or a beveled joint design may be required depending on the
amperage capability of your machine.
Fig. 47
8619470
GASLESS FLUX-
CORED WIRE
Table 3
Fig. 46
Fig. 48
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