Figure 2-3.—Self-plugging rivet (mechanical lock).
2017-T4 rivet is identified by the raised teat on the
head, while the 2024-T4 has two raised dashes on the
head.
ALLOY 5056 RIVETS.—These rivets are used
primarily for joining magnesium alloy structures
because of their corrosion-resistant qualities. They
are supplied in the H32 temper (strain-hardened and
then stabilized). These rivets are identified by a
raised cross on the head. The 5056-H32 rivet may be
stored indefinitely with no change in its driving
characteristics.
Blind Rivets
In places accessible from only one side or where
space on one side is too restricted to properly use a
bucking bar, blind rivets are usually used. Blind
rivets may also be used to secure nonstructural parts
to the airframe.
Figure 2-3 shows a blind rivet that uses a mechanical
lock between the head of the rivet and the pull stem. Note
in view B that the collar that is attached to the head has
been driven into the head and has assumed a wedge or
cone shape around the groove in the pin. This holds the
shank firmly in place from the head side.
The self-plugging rivet is made of 5056-H14
aluminum alloy and includes the conical recess and
locking collar in the rivet head. The stem is made of
2024-T36 aluminum alloy. Pull grooves that fit into
the jaws of the rivet gun are provided on the stem end
that protrudes above the rivet head. The blind end
portion of the stem incorporates a head and a land (the
raised portion of the grooved surface) with an
extruding angle that expands the rivet shank.
Applied loads for self-plugging rivets are
comparable to those for solid shank rivets of the same
shear strength, regardless of sheet thickness. The
composite shear strength of the 5056-H14 shank and
the 2024-T36 pin exceeds 38,000 psi. Their tensile
strength is in excess of 28,000 psi, Pin retention
characteristics are excellent in these rivets. The
possibility of the pin working out is minimized by the
lock formed in the rivet head.
Hi-Shear Rivets
Hi-shear (pin) rivets are essentially threadless
bolts. The pin is headed at one end and is grooved
about the circumference at the other. A metal collar is
swaged onto the grooved end. They are available in
two head styles—the flat protruding head and the
flush 100-degree countersunk head. Hi-shear rivets
are made in a variety of materials, and are used only
in shear applications. Because the shear strength of
the rivet is greater than either the shear or bearing
strength of sheet aluminum alloys, they are used
primarily to rivet thick gauge sheets together. They
are never used where the grip length is less than
the shank diameter. Hi-shear rivets are shown in
figure 2-4.
Figure 2-4.—Hi-shear rivet.
2-3
