786 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
only and must penetrate through the entire depth of
the joint. Sometimes a backing plate, or narrow strip
of material, is used in combination with a wider initial
gap. This enables the welder to more easily penetrate
the plates when welding from the bottom of the groove
up to the surface.
T-Joint
A T-joint is made between two metal parts
located approximately at right angles to each other
in the form of a T. A gap may or may not be present
at the start of a T weld. The welded bead is positioned
at the intersection of the two parts. This is referred to
as a fi llet weld. See Figure 29-14. Like butt joints,
T-joints sometimes are only accessible to weld from
a single side.
Corner Joint
A corner joint is created between two members located perpendicular
or at an angle to each other. Welded containers such as toolboxes, fuel tanks,
and loader buckets usually have corner joints. The inside of a corner joint, if
accessible, can be welded with a fi llet weld similar to that used on a T-joint.
Welding the outside of a corner joint requires precise control of the heat
input and the deposition rate of the electrode. On thin metals, care must be
taken to avoid the overapplication of heat, which could lead to melting holes
in the base metal. A skillfully welded outside corner is rounded slightly from
the contour of the weld and requires little effort to clean the welded bead.
Edge Joint
An edge joint is formed when the edges of two or more parallel (or
almost parallel) members are welded along one of the fl ush edges. Precise
STEM STEM Connection Connection
Heat and Temperature
Heat and temperature are related but are
separate concepts. A material can contain a large
amount of heat energy but have a low temperature.
A material with high temperature can contain little
heat. An acetylene flame burns at a very high
temperature, but it must remain in contact with the
metal long enough to transfer adequate heat for
bending, welding, or cutting.
Heat is energy that is transferred by the
movement of molecules in a substance. The transfer
of energy results from a temperature difference—the
energy moves from a high-temperature material
to a low-temperature material. Temperature is a
measurement of the level of kinetic energy (energy
resulting from motion) in a material.
Goodheart-Willcox Publisher
Figure 29-14. A fillet weld. Note the concave form
of the bead.