Hex flange bolts are used on vehicle frames, especially truck frames, and anywhere a hex washer head bolt is needed. The large bearing surface distributes clamping force over a large area, allowing them to be used with irregular and oversized holes.hey are also known as: hex frame flange bolts, hex washer frame bolts, hex flange screws. Serrated hex flange bolts have teeth under their head that grip the mating surface to resist loosening. 12 point flange bolts, also called counterbore cap screws, are used in aircraft and aftermarket automotive applications because they are easily installed using a 12 point socket and pneumatic impact wrench, while motorcycle enthusiasts like the small, externally wrenched decorative head.
SERRATED FLANGE BOLT
A Serrated Hex Flange Bolt is an unslotted hex head screw with a unified thread pitch and a flange that has serrations under the head or on the bearing surface side.
Serrated hex flange bolts are designed for use in applications where loosening forces are present, such as vibration. The serrations grip to the bearing surface so that significantly more torque is needed to loosen than to tighten the screw. The flange provides more strength than a standard machine screw and eliminates the need for a lockwasher or locknut in certain applications.