WELDTECH WT200MP - MIG Welding Best Practices; Nozzle Angle Techniques; Establishing the Arc and Making Beads; Setting Power Source Controls

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WT200MP Welding Machine
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ing (pushing).Whether the operatoris left handed
or right handed has to be considered to realize the
eects of each angle in relation to the direction of
travel.
Nozzle Angle, Right Handed Operator
(Fig 1-10)
Direction of Travel
Leadingor“Pushing”
Angle(ForwardPointing)
Trailingor“Pulling”
Angle(BackwardPointing)
90
o
Establishing the Arc and Making Weld Beads
Before attempting to weld on a nished piece of
work, it is recommended that practice welds be
made on a sample metal of the same material as that
of the nished piece.
The easiest welding procedure for the beginner to
experimentwithMIGweldingistheatposition.The
equipment is capable of at, vertical and overhead
positions.
ForpracticingMIGwelding,securesomepiecesof16
or18gauge(1.5mmor2.0mm)mildsteelplate(150
x150mm).Use(0.8mm)uxcoredgaslesswireora
solid wire with shielding gas.
Setting of the Power Source
Power source and Current (WireSpeed) setting re-
quires some practice by the operator, as the welding
plant has two control settings that have to balance.
ThesearetheCurrent(WireSpeed)controlandthe
weldingVoltageControl.
The welding current is determined by the Current
(WireSpeed)control,the current willincrease with
increasedCurrent(WireSpeed),resultinginashorter
arc.LessCurrent(WireSpeed)willreducethecurrent
and lengthen the arc. Increasing the welding voltage
hardly alters the current level, but lengthens the arc.
Bydecreasingthevoltage,ashorterarcisobtained
with a little change in current level.
When changing to a dierent electrode wire dia
eter, dierent control settings are required. A thinner
electrodewireneedsmoreCurrent(WireSpeed)to
achieve the same current level.
A satisfactory weld cannot be obtained if the Current
(WireSpeed)andVoltagesettingsarenotadjustedto
suit the electrode wire diameter and the dimensions
of the work piece.
IftheCurrent(WireSpeed)istoohighfortheweld-
ingvoltage,“stubbing”willoccurasthewiredipsinto
the molten pool and does not melt. Welding in these
conditions normally produces a poor weld due to
lack of fusion. If, however, the welding voltage is too
high, large drops will form on the end of the wire,
causing spatter. The correct setting of voltage and
Current (Wire Speed) can be seen in the shape of
the weld deposit and heard by a smooth regular arc
sound.
Electrode Wire Size Selection
The choice of Electrode wire size and shielding gas
used depends on the following:
 • Thicknessofthemetaltobewelded
 • Typeofjoint
 • Capacityofthewirefeedunitandpowersource
 • Theamountofpenetrationrequired
 • Thedepositionraterequired
 • Thebeadproledesired
 • Thepositionofwelding
 • Costofthewire