possibility of the pin working out is minimized by the
indefinitely with no change in its driving char-
lock formed in the rivet head.
acteristics.
Self-Plugging Friction Lock
Blind Rivets
Self-plugging friction lock rivets are available in
In places accessible from only one side or where
universal and flush head styles and are manufactured
space on one side is too restricted to properly use a
from 2117 and 5056 aluminum alloy and Monel.
bucking bar, blind rivets are usually used. Blind rivets
Self-plugging friction lock rivets cannot be substituted
may also be used to secure nonstructural parts to the
for solid rivets, nor can they be used in critical
airframe.
applications, such as control surface hinge brackets,
Self-Plugging Mechanical Lock
wing attachment fittings, landing gear fittings, and
fluid-tight joints. Figure 3-4 shows a self-plugging
Figure 3-3 shows a blind rivet that uses a
friction lock rivet and the proper installation procedure.
mechanical lock between the head of the rivet and the
pull stem. Note in view B that the collar that is attached
Hi-Shear Rivets
to the head has been driven into the head and has
Hi-shear (pin) rivets are essentially threadless
assumed a wedge or cone shape around the groove in
bolts. The pin is headed at one end and is grooved about
the pin. This holds the shank firmly in place from the
the circumference at the other. A metal collar is swaged
head side.
onto the grooved end. They are available in two head
The self-plugging rivet is made of 5056-H14
styles--the flat protruding head and the flush
aluminum alloy and includes the conical recess and
100-degree countersunk head. Hi-shear rivets are made
locking collar in the rivet head. The stem is made of
in a variety of materials, and are used only in shear
2024-T36 aluminum alloy. Pull grooves that fit into the
applications. Because the shear strength of the rivet is
jaws of the rivet gun are provided on the stem end that
greater than either the shear or bearing strength of sheet
protrudes above the rivet head. The blind end portion of
aluminum alloys, they are used primarily to rivet thick
the stem incorporates a head and a land (the raised
gauge sheets together. They are never used where the
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
Figure 3-3.--Self-plugging rivet (mechanical lock).
Figure 3-4.--Self-plugging rivet (friction lock).
3-3
