What is the prevailing torque?

Prevailing torque is the turning resistance encountered when driving in a fastener such as a self tapping screw. The initial resistance required to cut the thread can sometimes be higher than the torque required to clamp two mating parts together.

How is prevailing torque measured?

So, the maximum locking (prevailing) torque going into the bolt is measured, as is the minimum torque required to remove the bolt. Semantically speaking, the torque value table measures the maximum torque for installation, and the minimum torque for removal. Not, a range for installation.

What is minimum prevailing torque?

The torque required to run a nut down a thread on certain types of nuts designed to resist vibration loosening. The resistance can be provided by a plastic insert or a noncircular head. PREVAILING TORQUE NUT.

What is prevailing torque type nut?

A locknut, also known as a lock nut, locking nut, self-locking nut, prevailing torque nut, stiff nut or elastic stop nut, is a nut that resists loosening under vibrations and torque. Prevailing torque nuts have some portion of the nut that deforms elastically to provide a locking action.

How do you measure a locknut?

No vernier caliper? No Problem a ruler will do the job. If you measured at 50mm the size is 50 divided by 5, this gives us an 10 sized lock nut , 30mm would give us an 6 sized lock nut (30/5=6). To measure a lock nut simply measure it’s bore and then divide the measurement by 5.

What is Breakloose torque?

Breakaway Torque. The minimum torque required to start rotation into a nut (in the case of a bolt) or into a pre-tapped hole (in case of a screw).

How do you do torque marks?

Mark the tightened fastener and surrounding application. In the tightening direction, begin to slowly apply force to the tool until the first movement in the fastener is noted. The reading recorded is a good indication of the original torque applied to the joint. This is the best way to determine residual torque.

What does breakaway torque mean?

Remember that breakaway torque is that moment in time when the previously torqued (static) fastener begins to move again (dynamic torque). Once that movement happens, it cannot be created or captured again. If you loosen the fastener, you’ve just changed the joint that someone worked so hard to create.

What is Max breakaway torque?

Breakaway torque is the maximum initial force applied when busting a fastener loose.

How do you measure break away torque?

To conduct this test, take a screw or bolt that is tightened down and begin to loosen it. When the fastener breaks loose, record the torque reading. The torque value to loosen the fastener is the approximate torque that was applied to the joint.

What is prevailing torque?

Prevailing torque is the amount of torque needed to run a nut down a thread on nuts that are designed to resist self-loosening under vibratory forces. These types of nuts are known as locknuts or prevailing torque nuts, as opposed to free-spinning nuts.

How do you measure prevailing torque?

To understand prevailing torque, first, you need to understand your breakaway value. After you apply your thread locker, hand tighten your screw. Let it sit for a day to properly cure. When you unscrew it, the force (measured in torque) that it takes to overcome the static friction is your breakaway value.

What is the purpose of the torque zone?

This zone monitors the initial peak prevailing or diving torque to ensure that it falls between expected limits. It is used to identify poor quality conditions of a bolted joint (e.g. undersized hole, tightening obstruction). A failure (High torque) in the Cut In zone stops the tightening step with a fault.

What is seating torque?

Note: Seating torque is the torque at which the head of the bolt is “seated” against the work piece after rundown of the fastener or at which consolidation of joint components is achieved.