Engineering
Hi-Shear's threaded fastener systems
are designed for
In most cases, the system consists of
a threaded pin and collar assembly. The threaded end of the pin has a hexagonal
shaped recess, to allow for one-sided installation and to reduce weight. The pin comes in a variety of head styles, to accommodate
flush or protruding requirements, and shear or tension
applications. Strength requirements are listed on the appropriate
standard pages.
|
Flush
Shear |
Protruding
Shear |
Flush
Tension |
Protruding
Tension |
|
 |
 |
 |
 |
The
threaded collar includes a mechanical locking device for vibration
resistance, and is designed with a frangible driving portion, which
shears off at a specified torque. The torque at which the driving
portion shears off (torque-off) determines the level of preload induced
in the pin and collar assembly. Torque-off ranges can be selected for
shear, tension and special applications. The torque-off and
strength requirements can be found on the applicable collar standard
pages. Locking torque values and preload requirements can be found
in the appropriate product specification.
Assembly
of the pin and collar system involves inserting the pin into a prepared
hole, engaging the hex socket in the pin (to prevent relative rotation
between the pin and the structure), and driving the collar until the
frangible portion shears off. Tension preload in the joint is
controlled through the torque-off value designed into the collar,
thereby eliminating the need for torque-controlled tooling.
Hi-Shear
recommends using hole sizes per NAS618. For Hi-Lok (HL) pins the holes
should be close tolerance, clearance-fit or transition-fit. If the
application would benefit from interference-fit (or transition-fit), the
user should select a Hi-Tigue ("HLT") pin. Hi-Lite (HST)
pins may be used in interference fit, transition fit or clearance fit
holes.
The majority of Hi-Shear's threaded fastener
systems use the following nomenclature conventions:
Basic Product Information,
such as the type of product (pin or collar), material, strength rating,
applicable usage, etc. is is indicated by the basic part number.
This consists of an alphabetic code to indicate the product line (HL for
Hi-Lok for example), and a number. A standard page is available
for each basic part number.
Finishes
for both pins and collars are indicated by code letters after the basic
part number. Available finishes are shown on the appropriate
standard pages.
Nominal thread size, in
1/32" increments, is indicated by the first dash number.
Maximum
grip length (for pins), in 1/16" increments, is indicated by the
second
dash number. Fasteners of a specific grip length can be used up to
1/16" below maximum grip (1/16" grip variation). Grip gages and protrusion gages
are available to help determine proper usage.
Examples:
HL11VAP6-4
-
HL11 (Basic part number):
100° flush shear head, Titanium, 1/16" grip variation, standard shank, Hi-Lok pin.
-
VAP (finish code): Hi-Kote 1
aluminum coating per Hi-Shear Spec. 294, and cetyl alcohol lube
per Hi-Shear Spec. 305 (as indicated in HL11 standard page)
-
6 (first dash number): 6/32" or 3/16"
nominal thread size
-
4 (second dash number): 4/16" or 1/4"
maximum grip (grip range from 3/16" to 1/4")
HST73PB6
-
HST73 (Basic part number):
17-4PH Stainless steel, 1/16" grip variation,
tension-application,
standard and 1/64" oversize, Hi-Lite collar
-
PB (finish code): Cadmium
plate per QQ-P-416, Type II, Class 2, and
cetyl alcohol lube per Hi-shear spec. 305 (as indicated in HST73 standard page)
-
6 (first dash number): 6/32" or 3/16"
nominal thread size
Repair fasteners are available in
1/64" and 1/32" oversize shank diameters, with appropriate
mating collars.
For
system integrity, only collars and pins of the same product family
should be used in combination with one another. Never use a
tension-rated collar with a shear-rated pin. Please contact
us if you have a specific application issue you would like
additional assistance with.
Hi-Shear maintains an active research
and development group constantly working to create innovative fastener
and coating design solutions for the aerospace industry.
Please e-mail us (engineering@lisi-aerospace.us)
with any technical questions regarding Hi-Shear products.
