Thread strength
Thread strength
Nut threads are designed to support the rated clamp load of their respective bolts. If tapped threads are used instead of a nut, then their strength needs to be calculated. Steel hardware into tapped steel threads require a depth of 1.5× thread diameter to support the full clamp load.
If an appropriate depth of threads are not available, or they are in a weaker material than the cap screw, then the clamp load (and torque) needs to be de-rated appropriately.
Threads are usually created on a thread rolling machine. They may also be cut with a lathe, tap or die. Rolled threads are about 40% stronger than cut threads.