WINTER 2021

128
THE DISTRIBUTOR’S LINK
ANTHONY Di MAIO SELECTING THE CORRECT BLIND RIVET from page 50
¤ Under-Grip
FIGURE 2 - RIVET BODY LENGTH IS TOO LONG
TOO LONG
When a blind rivet is used in a grip range that is smaller
than the minimum specification for this blind rivet, the extra
length rivet body will form a curve when setting the blind rivet.
This curved rivet body can apply resistance to the mandrel
when setting and can cause pre-mature mandrel break. This
pre-mature mandrel break will reduce the clamping load on
the riveted joint and give you a loose assembly.
¤ ProperGrip
FIGURE 3 - RIVET BODY LENGTH IS CORRECT
diameter is given by all blind rivet manufacturers. It is
necessary to stay within the specified hole diameter on
the upset side of the application because the mandrel
head will stop at the upset side. If a larger hole is
necessary because of hole line-up, the large hole should
be on the flange side of the blind rivet.
FIGURE 4
If oversized holes are used on both the upset and
flange side of the blind rivet, the mandrel head will
entre the rivet body and will not meet resistance until it
contacts the flange of the blind rivet and the mandrel will
than break. When this occurs the area where the mandrel
breaks it is now protruding outside from the flange of the
set blind rivet. This condition is dangerous and someone
could injure themselves.
FIGURE 5
Burr
CORRECT LENGTH
When the proper length blind rivet is used in the
correct specified work thickness, you will have a captured
mandrel head and a low profile on the upset side of the
riveted joint.
Material To Be Riveted
Some applications are may up of dissimilar material,
such as plastic to aluminum. The hardest of the material
should be on the upset side because the mandrel head
should stop at the work thickness when setting the
blind rivet. If the softer material is on the upset side the
mandrel head will travel down into the rivet body until it
contacts a resistance greater than the mandrel tensile
strength and break. When soft material is used it on the
upset side of the riveting application, a blind rivet washer
is used for the blind rivet to upset against. Blind rivet
washers are 1/16 inch thick, so the blind rivet grip range
must be 1/16 inch longer than the total work thickness to
accommodate the thickness of the washer.
Hole Size
The recommended hole size for each blind rivet
Open-end
blind rivet
with mandrel
in place
Mandrel being
removed after
setting rivet
Mandrel
breaks free
As the illustration shows, it is the pulling of the
mandrel that sets the blind rivet. The tensile strength of
the mandrel is critical to achieve a tight riveted assembly.
This is why the Industrial Fasteners Institute (IFI) list in
their blind rivet specifications the minimum and maximum
tensile values of all mandrels for all diameter blind rivets
and in all alloys. If the IFI did not have minimum mandrel
tensile requirements, the mandrel will have pre-mature
breaks resulting in a loose assembly. If IFI did not have
maximum mandrel tensile requirements, the mandrel
head will pass through and out the flange of the blind rivet
when the blind rivet is set.
ANTHONY Di MAIO