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Hi-Shear's threaded fastener systems are designed for

  • single use

  • high strength

  • controlled preload

  • permanent airframe assembly

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.



  • 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")


  • 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



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