Crown CT33125 Manual Original página 21

Scale marking is done such that turning of control 4 for
one mark will change the welding current on 10%� If con-
trol 4 set in position 0 - function hot start switched off� If
control 4 set in position 10 - increase of the welding cur-
rent at the moment of ignition of the welding arc on 100%�
Arc force ("ARC FORCE" control)
The arc force function allows the sticking of the elec-
trode to a piece to be welded to be prevented�
When reducing the distance between the electrode
and the piece to be welded, the welding current is in-
creased for a short time which allows the metal of the
electrode and a work piece to be fused immediately,
thus increasing the arc gap�
[CT33139, CT33127, CT33126]
Control 9 can change the arc dynamics - lesser values
provide for smaller metal splashing while bigger values
provide for deeper fusion penetration�
Easy start
The easy start function (increased voltage of idle run-
ning) facilitates the lighting up of the welding arc�
Recommendations on the machine op-
eration
Preliminary works (see fig. 3)
• Finish the edges of work pieces to be welded is rec-
ommended�
• Angle of flare (a, see fig. 3.1) - is carried out
when metal is more than 3mm thick� Absence of
grooving can result in spilling on section of weld, and
also in overheating and burning of metal; atabsence
of grooving, for maintenance of weld penetration al-
ways try to increase size of a welding current�
• Backlash (b, see fig. 3.2) - correctly fixed before
welding, allows full weld penetration on section of
weld at imposing the priming layer of a seam�
• The length of a sheet bevel (c, see fig. 3.3) -
adjusts smooth transition from thicker welded detail
to more thin, thus stress concentrators in welded
structures are eliminated�
• Clean welding surfaces from rust and paint coatings�
• Please remember that a large quantity of heat is
released during welding which can damage the sur-
rounding items, therefore, carefully choose the site
and take appropriate actions to prevent fire.
Electrodes
The right choice of electrodes, to a great extent, pre-
determines the welding seam quality and the opera-
tion speed� Before purchasing electrodes, carefully
examine the recommendations of their use� Consult a
specialist if necessary� It is also important to observe
the electrode storage conditions�
General operation recommendations (see fig. 3)
The recommendations below apply to all
machines connected through a socket
connector. In the case of stationary con-
nection the machine assembly and net-
work connection will be done beforehand.
• Place the machine in an even, dry, not vibrating
surface observing all above-mentioned safety proce-
dures�
• Connect the ground wire�
• Connect the welding cables to the machine� Weld-
ing can be performed with direct and reverse polarity�
The selection of polarity depends on the materials to
be welded and the recommendations on how to use
electrodes�
• Direct polarity - connect electrode holder 14
to socket "-" 10, connect earth clamp 13 to sock-
et "+" 11� In such a mode the electrode heats less
than the basic metal, the electrodes get fused slow-
er, the welding joint is completed with a deeper pen-
etration�
• Reverse polarity - connect electrode holder 14
to socket "+" 11, connect earth clamp 13 to sock-
et "-" 10� In such a mode the work piece is heated
less than the electrode which can be used for weld-
ing high-carbon, alloy and special steels sensitive to
overheat as well as for welding sheet metal�
• Press the lever of the electrode holder 14 and install
the electrode end (the end free from coating) into elec-
trode holder 14 and then release the lever�
• Fix earth clamp 13 on one of the parts to be welded�
• Connect the machine to the mains and switch it on�
• Set the welding current value using control 5� The
selection of welding current depends on the electrode
to be used, thickness of material to be welded, spatial
position of a seam etc�
• Choose additional welding parameters (arc force
etc), if your machine has these functions�
• Ignite the welding arc in one of two ways: ignition
by touching (see fig. 3.4); ignition by scratching (see
fig. 3.5).
• The main practices of welding electrode handling
are described below:
• usually welding is carried out with vertically po-
sitioned electrode or at its inclination concerning a
seam, in a corner forward or back� When welding by
a corner back, it is provided better fusion and smaller
width of a seam (but performance of work in this case
demands the certain skill);
• progressive
fig. 3.6) - on a direction of an axis of the electrode, for
maintenance of necessary arch length which should
make 0,5-1,1 of electrode diameter� The length of an
arch renders the serious influence on quality of a weld-
ed seam and its form� A long arch causes intensive oxi-
dation and nitration of the fused metal, and increased
splashing of it;
• longitudinal movement of an electrode (see
fig. 3.7) - for formation of a welded seam� Speed of
movement of an electrode depends on electric cur-
rent, electrode's diameter, type and spatial position of
a seam;
at the high speed of an electrode the basic metal
has no time for fusion, what results in insufficient
depth of weld fusion spill is formed;
insufficient speed of moving of an electrode re-
sults in overheating and arc burn (through fusion)
of metal;
correctly chosen speed of longitudinal movement
along an axis of a welded seam allows obtaining its
width on 2-3mm more than diameter of an electrode;
• lateral movement of an electrode (see fig. 3.8) -
for formation of the widened welded seam� An elec-
trode is moved in lateral oscillatory movements more
often with constant frequency and the amplitude,
combined with progressive motion of an electrode
English
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motion of an electrode (see