What is rundown torque?
What is rundown torque?
If the threads are damaged or covered with dirt, you can feel some resistance before the fastener actually pulls the parts together. This is called “run-down” torque. Then, as you apply more torque, the nut does NOT move until you reach a higher value of torque.
What do torque values mean?
The measure of torque equals force multiplied by distance. A lug nut, for example, may have a torque value of 75 foot-pounds. Imagine having a wrench 1 foot in length with a 75-pound weight at the end, this resulting force is equal to a torque of 75 ft-lbs.
How do you determine running torque?
Begin with the formula T = K x U x D x P, where T is the torque, K is a standard representing 1.33, U is the coefficient of friction, D is the diameter of the fasteners, and P is the necessary preload.
What is rundown angle?
When tightening and measuring Torque, ‘Angle’ is the degrees of rotation that a fastener turns during its rundown process. For example, if a Torque Wrench was to turn and tighten a bolt in one full rotation, this would be 360 degrees.
Is torque a friction?
The torque can be affected by an opposing force that results from a resistant surface. This opposing force is referred to as friction. The frictional torque, therefore, is calculated as the difference between the applied torque and the resulting net, or observed, torque.
What is drag torque for a self-locking nut?
Free running, prevailing, or friction drag torque is the amount of torque it takes to turn the nut on the threads. This value will be very small for a plain nut and somewhat higher for a self-locking nut. Regardless of the number, this torque value must be added to the desired torque to achieve final torque.
What is torque in quality control?
If the torque is too low, the bolt tension won’t meet functional requirements. Either outcome can cause significant problems. The most common method of bolt tightening in a controlled fashion is to tighten to a specific torque, otherwise known as torque control.
Which occurs first clamping force or torque?
Designers typically qualify clamp force of a bolted joint by the amount of torque applied to fasteners holding it, either as they’re tightened or after the fact. This is because torque must first overcome under-head and thread friction before clamp loads build.
What percentage does clamping force contribute to overall torque level?
However, only about 10% of the torque applied is transferred into clamping force. The remaining tightening force is consumed in friction in the screw joint – 40% of the torque to overcome the friction in the thread and 50% in friction under the screw head.
What does the phrase ” running torque ” mean?
I would like to know the meaning of the phrase and especially the meaning of “running torque”: Torque the inner plug to between 75 and 85lbf.in. Loosen half a turn and RETORQUE to between 15 and 20lbf.in more than the running torque.
What’s the proper torque to run a wrench to?
So if you measure 30 inlb while spinning the nut down before it clamps down, you add that to the 100 inlb value, and run the wrench to 130 and will have the proper 100 inlb application to the bolt or stud. The proper procedure is to run the nut or bolt down to maybe half a turn to contact (washer still loose).
What does break away mean on a torque wrench?
The break away represents that torque available as a self locking feature that prevents the screw from vibrating out once tightened. But as you are turning the fastener to tighten it, some of the torque measured by the torque wrench is wasted in run on torque.
When to use running torque on an aircraft?
On aircraft cylinders, where a precise torque application is vital, it’s standard procedure to use lots of the recommended oil on the nut and threads to get the thread friction, and the nut to flange friction, as low as possible.
What is rundown torque? If the threads are damaged or covered with dirt, you can feel some resistance before the fastener actually pulls the parts together. This is called “run-down” torque. Then, as you apply more torque, the nut does NOT move until you reach a higher value of torque. What do torque values mean?…