Expandable Diameter Fastener (EDF)
Expandable diameter fasteners (EDFs) utilize mechanical sleeves to increase functional capability and performance. The EDF has tapered sleeves or bushings that, when activated, expand to create a tight fit in a hole. These sleeves can be activated by various means, including the use of a nut or bolt for torque, or other mechanisms such as a wraparound cam handle.
The EDFs are composed of several parts: core bolt/pin, bushing assembly, actuation system and accessories. The bushing assembly is composed of several internally and externally threaded segments as well as spaces and locking options. The actuation system can be a single adjusting nut or as complex as a wraparound cam handle. Accessories that can be utilized are lanyards, lock rings and various locking nuts.
Bolt: This bolt design utilizes a core bolt and nut on the opposite end.
Shaft: This design tightens the product using nuts on both ends of the shaft.
Blind applications: These fasteners are used in applications where access is limited to only one side. Additionally, these blind EDFs can be installed using a cam or nut.
Wraparound cam handle: The wraparound cam handle has a spring clip that locks the handle in a closed position. The hole sizes range from 0.375 to 1.50 in.
Both the blind EDF and wraparound cam handle EDF – once adjusted for required radial tightness – don’t need tools if the installations or removals are in the same hole. All these EDFs are available in a variety of materials and finishes for extreme corrosive or high-temperature environments.
How the EDF works
Step 1: EDF is inserted into the joint.
Step 2: EDF’s nut is tightened.
Step 3: Bushing expands into the joint, providing a tight radial fit.
The radial tightness of these EDFs results in minimized vibration, cyclic fatigue loads and shock-load resistance.
The expandable diameter allows EDFs to create a tight, zero clearance, radial fit.
These EDFs provide superior hole alignment compared to traditional nut and bolt systems. As a result, they can reduce substantial bolt damage and installation errors.
Installation of an EDF is simple and quick because of its secure fit capabilities. In addition, any operator can install this fastener with minimal instruction. Therefore, these installations can be repeated with ease.