The reason we use a bolt tightening sequence is to reduce the loss of pre-load in the bolt. If pre-load is lost, the bolt will relax, potentially leading to detrimental failure. A loss of preload can result from differences in thermal expansions between the bolt and the joint, along with other mechanisms.
Why do we need to measure the torque required to tighten a bolt?
When you are tightening a threaded fastener a significant amount of torque is needed to overcome friction in the threads and under the nut face (or the bolt head, if the bolt is rotated).
What is the tightening torque?
Torque tightening is the accurate application of torque to a nut so that a bolt can hold its load securely without breaking. … When you apply the right amount of torque, the bolt is properly stretched so that it can act as a solid spring to clamp the two materials together.
What is the tightening sequence?
Bolt tightening sequence, or torque sequence, is defined in the torque tightening procedure. Flange joints are torqued tight with the help of a torque wrench (manual or hydraulic). The clamp load produced during tightening is higher than 75% of the fastener’s proof load.
What is star pattern for tightening bolts?
For all 5-bolt parts, you’ll want to tighten them down using a “star” pattern. Starting at top-dead-center, tighten the first bolt until it’s just begun to tighten. Going clockwise or counterclockwise, skip the next bolt, and repeat the process. Keep tightening every-other bolt until all five are slightly tight.
What is a bolt tightening sequence?
There are many different things that determine whether a new flange connection will be secure and leak-free. One of the most important is the bolt tightening sequence. … The order in which you tighten the bolts and the load applied has a huge effect on the integrity of the joint.
What is the formula to calculate torque?
Mathematically, torque can be written as T = F * r * sin(theta), and it has units of Newton-meters. When the sum of all torques acting on an object equals zero, it is in rotational equilibrium.
How tight is hand tight torque?
Hand tight is on average about 2ft-lb.
What is torque Turning?
‘Torque to turn’ is what it takes to overcome friction and inertia in a rotating system. Breakaway torque is the turning force required to initiate rotation (similar to static friction), and running torque is the turning force required to keep a system in rotation (similar to kinetic friction). …
What is the difference between bolt tensioning and torquing?
Bolt torque and bolt tensioning are both legitimate ways to seal a joint. Bolt torquing exerts a rotational force on the fastener, while bolt tensioning involves stretching a fastener with what looks like a hydraulic load cell.
How does torque wrench work?
How Torque Wrenches work. These tools are calibrated to apply a certain amount of torque to a fastener. The amount of torque that is applied depends on the amount of force on the tool’s handle and the length of the wrench. … When the indicator determines the desired torque has been reached, stop twisting the bolt.
Is there a tightening pattern when tightening the lug nuts?
Tightening them in a cross pattern reduces the likelihood of things shifting and flexing, which means that your lugs will stay tight after you torque them. Using the above diagram, tighten your lug nuts in the correct order that corresponds with the number of lug bolts your wheel has.
Do you have to tighten lug nuts in a star pattern?
Tighten the lug nuts in a star pattern, not a circle pattern, so the wheel gets seated snugly. This assures the wheel isn’t askew, and doesn’t then pop into the proper place while you’re going down the road, loosening some of the bolts and causing wobbling or worse — like the nuts breaking and the wheel coming off.
What is the torque specification?
When attaching a wheel to a vehicle, torque specifications are the amount of force recommended on the hardware to ensure proper installation. … It can damage the wheel, strip the bolts and even cause the brake rotors to warp. Too much torque also can damage brake rotors.
Why is it important to torque critical fasteners to specific tightness?
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.
Why do we need torque?
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. … Multiply this torque force (in lb-ft.) by the axis’s rotational speed per minute (RPM) and you get the engine’s power output.
What is a prevailing torque?
Prevailing torque is defined as the driving torque required to overcome friction in a threaded fastening application, which produces no clamp load, or bolt stretch.
What happens if you don’t torque to spec?
Engines that are running, tend to vibrate. … 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.
What is the difference between torque and tensioning?
However, they use different means to accomplish it. “Torque” is simply a measurement of the twisting force required to spin the nut up along the threads of a bolt, whereas “Tension” is the stretch or elongation of a bolt that provides the clamping force of a joint. … The finish used on the bolts.