Lincoln Electric IM348 AC-225-GLM - Manual (Page 12)

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Do the following:
1. Learn to strike the arc by scratching the electrode over
the plate. Be sure the angle of the electrode is correct. If
you have a headshield use both hands.
2. When you can strike an arc without sticking, practice the
correct arc length. Learn to distinguish it by its sound.
3. When you are sure that you can hold a short, crackling
arc, start moving. Look at the molten puddle constantly,
and look for the ridge where the metal solidifies.
4. Run beads on a flat plate. Run them parallel to the top
edge (the edge farthest away from you). This gives you
practice in running straight welds, and also, it gives you
an easy way to check your progress. The 10th weld will
look considerably better than the first weld. By con-
stantly checking on your mistakes and your progress,
welding will soon be a matter of routine.
Common Metals
Most metals found around the farm or small shop are low
carbon steel, sometimes referred to as mild steel. Typical
items made with this type of steel include most sheet metal,
plate, pipe and rolled shapes such as channels, angle irons
and “I’’ beams. This type of steel can usually be easily
welded without special precautions. Some steel, however,
contains higher carbon. Typical applications include wear
plates, axles, connecting rods, shafts, plowshares and
scraper blades. These higher carbon steels can be welded
successfully in most cases; however, care must be taken to
follow proper procedures, including preheating the metal to
be welded and, in some cases, carefully controlling the
temperature during and after the welding process. For fur-
ther information on identifying various types of steels and
other metals, and for proper procedures for welding them,
we again suggest you purchase a copy of “New Lessons in
Arc Welding” (see page 23).
Regardless of the type of metal being welded, it is impor-
tant in order to get a quality weld that it be free of oil, paint,
rust or other contaminants.
Types of Welds
Five types of welding joints are: Butt Welds, Fillet Welds,
Lap Welds, Edge Welds and Corner Welds.
Of these, the Butt Weld and Fillet Weld are the two most
common welds.
Butt Weld
Butt Welds are the most widely used welds. Place two
plates side by side, leaving 1/16” (for thin metal) to 1/8”
(for heavy metal) space between them in order to get deep
penetration .
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 the thickness of
the material; thus the weld is only approximately 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.