Meaning
Mechanical binding mechanism relying on surface resistance to prevent relative movement between components. Fasteners use this friction lock when the tension in the bolt creates enough clamping force to stop the nut from rotating. It is common in wedge anchors and interference fits where the components are pressed together.
Reliability depends entirely on the coefficient of friction and the normal force applied to the surfaces.
Interference Grip
Design specifications for a friction lock must account for the surface finish of the mating parts. Smooth surfaces provide less resistance than textured ones.
Fastener Security
Vibration often causes the clamping force to dissipate over time. When a friction lock is the only thing holding an assembly together, the loss of tension leads to a total failure of the joint.
Torque Retention
Installation procedures specify a target preload to ensure the lock remains effective under load. Mechanics use calibrated wrenches to apply the exact amount of rotation needed to stretch the bolt. If the friction lock is called into service before the full torque is reached, the assembly will likely slip.
This slip increases the wear on the contact surfaces and eventually destroys the capability of the joint to hold a load.
