2024-01-23
Coatings and Clamp Load
When a bolt is tightened into a mating threaded part, the two components interact by pulling each other together. This force is called clamp load and is what keeps the joint from coming apart. Provided that the force pulling it together is greater than the outside forces (service loads) that are trying to pull it apart, no problem will result with the attachment. Unfortunately, friction plays a large part in this system. Of the 100% of torque applied to fasteners to pull them together, 50% is lost in underhead bearing face friction and 40% is lost through friction between the mating threads.