Why is it necessary to tighten the bolt initially?

Tightening the bolt puts the shank in tension, counteracted by compressive forces on the contact surfaces of the head and the nut, transferred from the parts. … Bolted joints generally withstand fatigue loading well, especially if the parts joined together are much stiffer than the bolt itself.

Why is it important to tighten nuts and bolts in the correct order?

A good tightening sequence ensures that an even preload distribution is achieved in the joint. Since joints containing conventional gaskets have a comparatively low compressive stiffness, bolt preloads in such joints are particularly sensitive to the tightening sequence.

Why is bolt preload important?

Bolt preload ultimately allows a fully tightened bolt to survive in an application where an untightened or loose assembly would fail very quickly. When tight, the joint provides a conduit for the force to flow through into the assembly materials themselves.

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Why is it important to tighten the bolts to the specified torque values?

Each bolt or nut you tighten on your car has calculated torque values specifically designed for assembly. … Both under torquing and over-torquing a bolt can have a catastrophic failure, therefore it is important to tighten each bolt or nut to the manufacturer’s specified values.

What could happen if you do not tighten bolts enough?

If the screws are not tight enough, they can come loose whilst driving. If the wheel bolts are too tight, the threads might get stripped or damaged. And this is where the torque wrench comes in. Using a torque wrench enables you to tighten up the wheel bolts to a specified torque.

Why do we torque bolts?

Torque is used to create tension. Bolts are used to affix two components so that they can resist tensile (pulling apart) and shearing (sliding apart) forces. After the nut has been turned onto the bolt, additional torque causes the nut to turn and stretch the bolt.

Does it matter if you tighten the nut or bolt?

There is no simple answer to this as in some instances, it is perfectly acceptable to tighten the bolt head while holding the nut in place. In other situations, it’s acceptable to tighten the nut.

What happens when a bolt is tightened?

What happens as a bolt is tightened? … When the joint members within the grip resist, the bolt begins to stretch like a stiff spring, developing tension and simultaneously compressing the components together creating the all-important clamp force.

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Why do we preload?

The purpose of preload in a bearing system is to eliminate clearance that is designed into standard ball bearings. … This space, if not taken up by a preload can allow the rolling elements to slide rather than roll, or even allow for races to misalign.

What is preload and tightening torque?

Preload from Torque Difference

Using torque–tension data, tightening torque is typically specified and applied with a torque wrench to achieve desired preload. … This removal torque is the torque required to overcome thread and nut friction minus the torque from bolt stretch.

Why is torque sequence important?

Because the joint surfaces compress, tightening one bolt in the vicinity of another will affect the preload generated by the first bolt tightened. A good tightening sequence ensures that an even preload distribution is achieved in the joint (See Dia. A).

What is torque and why is it important?

Torque is a crucial part of generating power from a car’s engine, as it represents the load an engine can handle to generate a certain amount of power to rotate the engine on its axis. The force is measured in pounds (lb) per foot (ft) of rotation around one point.

How is bolt torque required?


The general equation for bolt load based on applied torque is T = KFiDb where K = torque coefficient. K is a function of the coefficients of friction and collar friction in the joint, and these are based on variables such as surface finish, coatings, and so on.

What happens if you don’t torque a bolt?

In the case of insufficient torque, it’s the stud or the bolt itself that suffers all the impact, causing it to shear. Alternatively, the engine’s vibrations can cause the bolt or nut to come undone, displacing the tensioner.

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How do bolts tighten?

Tightening is done by turning the bolt with a certain torque, with 80% to 90% of this torque being carried away by friction in the thread and under the head.

What are the possible effects of over torquing or under torquing?

When the joint in question is over-torqued, the flange load can become uneven and weaken the effectiveness of the flange/bolt load. This in turn leads to an increase in blow-out pressure and hydrostatic force, which can cause joint failure.