What is a bolt tightening sequence?
Tightening sequence. The first pass, lightly tighten the first bolt then move directly across or 180 degrees for the second bolt, then move1/4 turn around the circle or 90 degrees for the third bolt and directly across for the fourth. Continue this sequence until all bolts are tightened.
Why do we use a sequence of tightening?
A good tightening sequence ensures that an even preload distribution is achieved in the joint (See Dia. A). Since joints containing conventional gaskets have a comparatively low compressive stiffness, bolt preloads in such joints are particularly sensitive to the tightening sequence.
What are the factors that determine a torque?
1. What are the factors determine the torque to a body? ο‚·There are several factors namely: the DISTANCE, FORCE and ANGLE. Distance, because, the further you place the force from the axis of rotation, the easier it is to rotate around that point.
Is there a way to measure the tightening torque?
The problem is that there is no practical way to measure the clamping force in normal production situations. Consequently the value of the clamping force is usually referred to as the tightening torque.
How is the tightening torque related to the clamping force?
Consequently the value of the clamping force is usually referred to as the tightening torque. As the clamping force is a linear function of both the turning angle of the screw and the pitch of the thread, there is a direct relation between the clamping force and the tightening torque within the elastic range of the screw elongation.
How does lubrication affect the tightening of a screw?
EFFECT OF LUBRICATION If a screw is lubricated, the friction in the threads and under the head is decreased and the relation between tightening torque and clamping force is changed. If the same torque is applied as before lubrication, a lot more torque will be trans- formed into clamping force.
What happens to torque when a screw is loosened?
Torque will continue to increase but at a lower torque rate during the deformation above the yield point. The plastic deformation will result in a permanent elongation of the screw if the joint is loosened. For very accurate clamping force requirements this area is sometimes deliberately specified for the tightening process.