Lincoln Electric IM556 AC-235 - Manual (Page 14)

– 14 –
Tack the plates at both ends, otherwise the heat will cause
the plates to move apart. (See drawing):
Now weld the two plates together. Weld from left to right
(if right-handed). Point the electrode down in the crack
between the two plates, keeping the electrode slightly tilted
in the direction of travel.
Watch the molten metal to be sure it distributes itself even-
ly on both edges and in between the plates.
Penetration
Unless a weld penetrates close to 100%, a butt weld will be
weaker than the material welded together.
In this example, the total weld is only 1/2 (12.7mm)the
thickness of the material; thus the weld is only approxi-
mately half as strong as the metal.
In this example, the joint has been flame beveled or ground
prior to welding so that 100% penetration could be
achieved. The weld, if properly made, is as strong or
stronger than the original metal.
Fillet Welds
When welding fillet welds, it is very important to hold the
electrode at a 45° angle between the two sides, or the metal
will not distribute itself evenly.
To make it easy to get the 45° angle, it is best to put the
electrode in the holder at a 45° angle, as shown:
Multiple Pass Welds
Make multiple pass horizontal fillets as shown in the
sketch. Put the first bead in the corner with fairly high cur-
rent. Hold the electrode angle needed to deposit the filler
beads as shown putting the final bead against the vertical
plate.
Welding in the Vertical Position
Welding in the vertical position can be done either vertical-
up or vertical-down. Vertical-up is used whenever a large,
strong weld is desired. Vertical-down is used primarily on
sheet metal for fast, low penetrating welds.
Vertical-Up Welding
The problem, when welding vertical-up, is to put the
molten metal where it is wanted and make it stay there. If
too much molten metal is deposited, gravity will pull it
downwards and make it “drip.’’ Therefore a certain tech-
(12.7 mm)