Figure 3-4.Gas tungsten arc welding (GTAW).
(GTAW) (fig. 3-4) and gas metal arc welding (GMAW)
(fig. 3-5). You will also hear these called TIG and
MIG. Gas shielded arc welding is extremely useful
because it can be used to weld all types of ferrous and
nonferrous metals of all thicknesses.
Now that we have discussed a few of the welding
processes available, which one should you choose?
There are no hard-and-fast rules. In general, the control-
ling factors are the types of metal you are joining, cost
involved, nature of the products you are fabricating, and
the techniques you use to fabricate them. Because of its
flexibility and mobility, gas welding is widely used for
maintenance and repair work in the field. On the other
hand, you should probably choose gas shielded metal
arc welding to repair a critical piece of equipment made
from aluminum or stainless steel.
No matter what welding process you use, there is
some basic information you need to know. The remain-
der of this chapter is devoted to this type of information.
Study this information carefully because it allows you
to follow welding instructions, read welding symbols,
and weld various types of joints using the proper weld-
Figure 3-5.Gas metal arc welding (GMAW).
To become a skilled welder, you first need to learn
the technical vocabulary (language) of welding. The
sections in this chapter introduce you to some of the
basic terms of the welding language. Once you under-
stand the language of welding, you will be prepared to
interpret and communicate welding information accu-
When welding two pieces of metal together, you
often have to leave a space between the joint. The
material that you add to fill this space during the welding
process is known as the filler metal, or material. Two
types of filler metals commonly used in welding are
welding rods and welding electrodes.
The term welding rod refers to a form of filler metal
that does not conduct an electric current during the
welding process. The only purpose of a welding rod is
to supply filler metal to the joint. This type of filler metal
is often used for gas welding.
In electric-arc welding, the term electrode refers to
the component that conducts the current from the elec-
trode holder to the metal being welded. Electrodes are