Welding Discontinuities And Defects - Helvi 1357 Manual De Uso Y Manutención

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and the workpiece. The wire "Stick out" (sometimes
improperly called arc length) should remain in
the range 5mm ÷ 10 mm in order to obtain best
welding (and sound) performances.
• Position the voltage switch in the desired po-
sition (TAB. 1, 2). Select lower position for lo-
wer thickness and higher settings for higher
thickness.
• Adjust the wire speed. Start using a trial me-
tal sheet thoroughly cleaned from layers of
rust or paint. Connect the ground cable to
the workpiece. Adjust the wire speed at high
setting. Press the torch switch (note: The torch
switch must be pressed thoroughly in order
to perform its three functions, gas flow, wire
feed and welding current). Start welding and
decrease the wire speed gradually. Conti-
nue to decrease the wire speed and listen
to the sound. The sound will change from a
crackling noise to a regular and strong buz-
zing (similar to the sound of frying bacon).
This buzzing sound indicates the correct
wire speed for the workpiece being welded.
When the current regulation is changed set
again the wire speed. Start always from a
higher wire speed. This operation prevents
from damaging the contact tip during wel-
ding. During welding the torch should be
kept with the 45° angle from the workpiece.
Keep the top of the nozzle at 5-10mm from
the work-piece.
WELDING DISCONTINUITIES
AND DEFECTS
•Defect: The wire pushes the torch back from the
workpiece.
Cause: Excessive wire speed.
•Defect: The wire sticks on the contact tip.
Cause: Low wire feeding.
•Defect: Excessive welding spatters
Cause: Erratic wire feeding, improper torch position
(too inclined)
•Defect: Arc is unstable
Cause: Low voltage, erratic wire feeding, inade-
quate gas flow rate.
•Defect: Inadequate penetration.
Cause: Welding current too low, excessive travel
speed, torch travel direction should be reversed.
•Defect: Cracking
Cause: Base material dirty, welding current too low,
excessive welding voltage, rust on the electrode wire.
•Defect: Porosity
Cause: Cylinder of shielding gas empty, leaky gas
hoses, wrong adjustment of gas flow rate.
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