The high-shear pin rivet family includes fasteners, such as  the Hi-Lok$^{®}$, Hi-Tigue$^{®}$, and Hi-Lite$^{®}$ made by Hi-Shear  Corporation and the CherryBUCK$^{®}$ 95 KSI One-Piece Shear  Pin and Cherry E-Z Buck$^{®}$ Shear Pin made by Cherry$^{®}$  Aerospace. The threaded end of the Hi-Lok$^{®}$ two-piece fastener contains  a hexagonal shaped recess.  [Figure 4-104]  The hex tip of an  Allen wrench engages the recess to prevent rotation of the  pin while the collar is being installed. The pin is designed  in two basic head styles. For shear applications, the pin is  made in countersunk style and in a compact protruding head  style. For tension applications, the MS24694 countersunk and  regular protruding head styles are available. The self-locking, threaded Hi-Lok$^{®}$ collar has an internal  counterbore at the base to accommodate variations in  material thickness. At the opposite end of the collar is a  wrenching device that is torqued by the driving tool until it  shears off during installation, leaving the lower portion of  the collar seated with the proper torque without additional  torque inspection. This shear-off point occurs when a  predetermined preload or clamp-up is attained in the fastener  during installation. flats to shear when the proper torque has been reached. The  threads match the threads of the pins and have been formed  into an ellipse that is distorted to provide the locking action.  The recess serves as a built-in washer. This area contains a  portion of the shank and the transition area of the fastener. The hole shall be prepared so that the maximum interference  fit does not exceed 0.002-inch. This avoids build up of  excessive internal stresses in the work adjacent to the hole.  The Hi-Lok$^{®}$ pin has a slight radius under its head to increase  fatigue life. After drilling, deburr the edge of the hole to allow  the head to seat fully in the hole. The Hi-Lok$^{®}$ is installed in  interference fit holes for aluminum structure and a clearance  fit for steel, titanium, and composite materials. The Hi-Tigue$^{®}$ fastener offers all of the benefits of the Hi- Lok$^{®}$ fastening system along with a unique bead design that  enhances the fatigue performance of the structure making  it ideal for situations that require a controlled interference  fit. The Hi-Tigue$^{®}$ fastener assembly consists of a pin and  collar. These pin rivets have a radius at the transition area.  During installation in an interference fit hole, the radius area  will “cold work” the hole. These fastening systems can be  easily confused, and visual reference should not be used for  identification. Use part numbers to identify these fasteners. The Hi-Lite$^{®}$ fastener is similar in design and principle to  the Hi-Lok$^{®}$ fastener, but the Hi-Lite$^{®}$ fastener has a shorter  transition area between the shank and the first load-bearing  thread. Hi-Lite$^{®}$ has approximately one less thread. All Hi- Lite$^{®}$ fasteners are made of titanium. The advantages of Hi-Lok$^{®}$ two-piece fastener include its  lightweight, high fatigue resistance, high strength, and its  inability to be overtorqued. The pins, made from alloy steel,  corrosion-resistant steel, or titanium alloy, come in many  standard and oversized shank diameters. The collars are made  of aluminum alloy, corrosion-resistant steel, or alloy steel.  The collars have wrenching flats, fracture point, threads, and  a recess. The wrenching flats are used to install the collar.  The fracture point has been designed to allow the wrenching  These differences reduce the weight of the Hi-Lite$^{®}$ fastener  without lessening the shear strength, but the Hi-Lite$^{®}$  clamping forces are less than that of a Hi-Lok$^{®}$ fastener.  The Hi-Lite$^{®}$ collars are also different and thus are not  interchangeable with Hi-Lok$^{®}$ collars. Hi-Lite$^{®}$ fasteners can  be replaced with Hi-Lok$^{®}$ fasteners for most applications, but  Hi-Loks$^{®}$ cannot be replaced with Hi-Lites$^{®}$.  The CherryBUCK$^{®}$ is a bimetallic, one-piece fastener that  combines a 95 KSI shear strength shank with a ductile,  titanium-columbium tail. Theses fasteners are functionally  interchangeable with comparable 6AI-4V titanium alloy  two-piece shear fasteners, but with a number of advantages.  Their one piece design means no foreign object damage  (FOD), it has a 600 °F allowable temperature, and a very  low backside profile. Hi-Lite$^{®}$ Fastening System CherryBUCK$^{®}$ 95 KSI One-Piece Shear Pin  Figure 4-104.  Hi-Lok®. 4-51 •  A hollow-mill collar cutter can be used in a power hand  drill to cut away enough collar material to permit the  rivet to be tapped out of the work. Hi-Tigue$^{®}$ Fastening System Hi-Lok$^{®}$ Fastening System