How to measure the torque on bolts?
The torque value of a bolt can be checked in 3 ways:
- The movement check:
- The loosening check:
- The marking check:
How do you measure the torque of a tightened bolt?
The torque value of a bolt can be checked in 3 ways: The movement check: After fastening the bolt, make use of a torque measuring tool to mark off the tightened bolt and the product/workpiece. Apply additional force in the tightening direction until movement is noticed. Recording the reading will indicate the residual torque originally applied ...
How to calculate the stress on a bolt?
The resultant axial load on a bolt depends upon the following factors :
- The initial tension due to tightening of the bolt,
- The extenal load, and
- The relative elastic yielding (springiness) of the bolt and the connected members.
How do you calculate bolt tension?
- Tension due to gravity (T g) = 98cos (15) = 98 (0.96) = 94.08 Newtons
- Centripetal force (F c) = 10 × 1.5 2 /1.5 = 10 × 1.5 = 15 Newtons
- Total tension = T g + F c = 94.08 + 15 = 109.08 Newtons.
How is bolt torque calculated?
1:054:38how to calculate bolt tightening torque - YouTubeYouTubeStart of suggested clipEnd of suggested clipMean value of nut factor is 0.2. Now we will calculate preload which is basically tensile load inMoreMean value of nut factor is 0.2. Now we will calculate preload which is basically tensile load in the bolt. If we load the bolt up to its yield strength then bolt will have permanent deformation.
How do you torque a torque to yield a bolt?
0:374:34How to Install Torque-To-Yield Head Bolts With a Torque Angle Gauge ...YouTubeStart of suggested clipEnd of suggested clipYou're going to need a torque wrench a torque angle gauge a socket. And adapter if necessary.MoreYou're going to need a torque wrench a torque angle gauge a socket. And adapter if necessary.
What is a torque to yield bolt?
What is a torque-to-yield bolt? It is a one-time-use fastener that is designed to stretch during the torquing process (installation). Because of this stretching, the integrity of the bolt is compromised. These bolts cannot and should not be reused due to the stress caused to the bolt during its first installation.
How do you calculate torque formula?
The magnitude of torque is equal to the product of the magnitude of the force and the lever arm. The dimensional formula for force is [M¹L¹T⁻²] while for a lever arm it is [L]. Hence, the dimensional formula for torque is [M¹L²T⁻²].
How do you adjust torque to yield?
8:1624:00Torque to yield bolts & angle tightening explained - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe more tension there is they're clamping the thing down the harder. It is to move the head and theMoreThe more tension there is they're clamping the thing down the harder. It is to move the head and the face of the nut.
What is yield point torque?
A torque to yield fastener (TTY) or stretch bolt is a fastener which is torqued beyond the state of elasticity and therefore undergoes plastic deformation, causing it to become permanently elongated.
Why are bolts torque to yield?
First, it overcomes friction between the threads in the block and the bolt as well as friction between the cylinder head the underside of the bolt head. Secondly, the torque stretches the fastener slightly to establish and maintain the desired clamp load on the gasket.
What happens if you over torque a torque to yield bolt?
3:0912:42What happens when you over torque a bolt? - YouTubeYouTubeStart of suggested clipEnd of suggested clipOr torque to yield bolts beyond the yield point the bulk can still be stretched a bit and hold up toMoreOr torque to yield bolts beyond the yield point the bulk can still be stretched a bit and hold up to higher tensile load but eventually that tensile strength will plateau.
How does a torque to yield bolt differ from a standard bolt?
The torque to yield bolt has a smaller shaft diameter and can adapt to the expansion of the aluminum cylinder head, applying a more constant clamping force. As a result, they are popular in modern vehicles. Many vehicles have these bolts in the engine and even the suspension.
How do you solve torque problems?
7:349:05How to Solve Torque Problems Easily - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo that we reach our rotational equilibrium. So now all that we have to do is we have to realizeMoreSo that we reach our rotational equilibrium. So now all that we have to do is we have to realize that the counterclockwise torque is equal to ten times M times the lever arm of two.
What is the right hand rule torque?
To use the right hand rule in torque problems, take your right hand and point it in the direction of the position vector (r or d), then turn your fingers in the direction of the force and your thumb will point toward the direction of the torque.
How do you convert torque to load?
To calculate load torque, multiply the force (F) by the distance away from the rotational axis, which is the radius of the pulley (r). If the mass of the load (blue box) is 20 Newtons, and the radius of the pulley is 5 cm away, then the required torque for the application is 20 N x 0.05 m = 1 Nm.
What is torque reduction due to lubrication?
torque reduction due to lubrication (%) Note that standard dry torques are normally calculated to produce a tensile stress - or axial force or clamp load - in the bolt that equals to 70% of minimum tensile strength or 75% of proof strength.
What is the proof load for a M30 bolt grad 8.8?
The proof load for a M30 metric bolt grad 8.8 is 337000 N. The torque required to achieve this tension with a dry bolt with 0% lubrication can be calculated as
What is torque in a bolt?
What is Torque? Torque is a twisting force measuring force multiplied by distance. It is the application of force acting at a radial distance to create tension in threaded fasteners. When the nut and bolt are tightened, the thread converts the applied torque into tension, which is converted into a clamping force.
What is the k factor of a bolt?
The “D” represents the bolt’s diameter, the “F” is the axial bolt force, and the “K” represents “k-factor” or “nut factor” which is a variable based on the use or absence of lubrication. The k-factor for a non-lubricated joint is 0.2.
What is torque audit wrench?
After you’ve tightened your fastener, use a torque audit wrench to slowly apply force in the tightening direction until you notice the first movement in the fastener. The reading is a reliable indication of the originally-applied torque. This is the most trusted measure of torque after tightening.
How accurate are torque wrenches?
When calculating torque, always remember that torque wrenches are not perfectly accurate. If you’d prefer, please contact us regarding the optimal torque for various combinations of bolt diameter, thread type, and grade or class.
How to mark a bolt after tightening?
Mark the surface of the fastener after tightening the bolt or nut, and continue that mark to the surface that it’s being fastened to. Now loosen the fastener, wait a moment, and re-tighten until the marks you just made align. The torque required to get to that point is a good reference to the original torque used.
What happens when a bolt stretches?
When the bolt stretches, it becomes a solid spring that clamps the components together. The components won’t be pulled apart if the clamp load is not exceeded by the tensile load. Under shear loads, the increased friction prevents relative motion of the components, preventing material failure.
Can an under torqued bolt break?
Having the wrong materials, or an incorrect torque calculation can be potentially hazardous. An under-torqued bolt will deform and won’t be able to provide as much clamping force as needed, while an over-torqued bolt will break.
Why use torque on bolts?
Many vehicle manufacturers use torque to yield bolts; especially on engines with aluminum heads and or in conjunction with (MLS) head gaskets. They provide more consistent clamping loads, across the entire head-to-block mating surface. When a shop manual indicates that a bolt is to be discarded and new ones used;
Does lubricant affect torque?
Starting the bolt turning takes more force than keeping it turning. The tighter the bolt, the more stiction can affect torque readings. Lubrication helps the threads slide easier but, one lubricant differs from another in their lubricating qualities. Manufacturers will specify what type of lubricant, if any to use on a bolt when torquing it. Using the wrong lubricant will affect the clamping load.
Do bolts stretch?
Bolts are elastic by nature, meaning that within their elastic range; they’ll stretch as load on the bolt increases. Typical bolts can be an issue when you use them on aluminum heads and; with a gasket that doesn’t relax, like an (MLS) gasket. The expansion rate of aluminum heads will stretch typical bolts, past their yield point and can snap them.
What is the coefficient of torque?
The coefficient of torque can be estimated as 0.2 if the condition is unknown. Example:
What is a bolted joint?
A bolted joint is the joining of two pieces of material using a bolt (or other threaded fastener) and a nut or threaded/tapped hole. It is expected that the bolted joint will be able to withstand the maximum applied forces to the joint over its lifetime. When designing a bolted joint, it is important to consider the type ...
What is preload in a bolted joint?
The preload of a bolted joint is the initial axial force applied by the fasteners across the joint. The preload should be equal to or larger than the maximum expected applied axial forces to the bolted joint in order to avoid separation of material. Preload. The general rule of thumb for bolted joint design ...
What is the yield point of a bolt?
A bolt’s yield point is where the stress placed on a fastener surpasses its ability to recover its elasticity. Remember: Steel may seem firm, but it’s actually an elastic material. That means when you fasten a bolt, you are actually stretching the material. The stress applied to a bolt is known as “tensile stress” or “preload.”.
What does it mean when a fastener is a plastic deformation?
When a fastener reaches a point of plastic deformation, in simple terms, this means the fastener won’t go back to its original shape. (Technically, this means the bolt won’t go back to being within .02% of its original shape.)
Can you tighten a bolt past the yield point?
It’s easy to tighten the bolt past the yield point and not know you are past permanent deformation. And notice how even after the steel bolt has surpassed minimum tensile strength, a nut will still run up and down the threads just fine.
What is a torque turn to tighten?
It’s called Torque Turn to Tighten (TTT), often referred to as angle turn. With this method, you use a relative low torque to run down and align the fastener (Illustration 5), then rely solely on a measured turn to tighten the fastener to the desired level.
Where is the root diameter of a fastener located?
This occurs in the threaded area (the root diameter of a fastener is smallest in the threaded area), usually about one thread above where the fastener is engaged in the threads of the nut or the block (the threads of the nut or engine block support the fastener resisting yield).
Why are critical fasteners identified?
Critical fasteners can be identified because the repair procedure for the engine details exact tightening information. Pan bolts, timing cover bolts and valve cover bolts are examples of non-critical fasteners having no detailed fastening procedures. Here, we’ll focus on critical fasteners.
What happens when a fastener is stretched?
When a fastener is stretched into the yield zone, some of the elasticity is permanently lost, and the fastener will remain somewhat elongated when the load is removed.
What happens when you stretch a fastener into the yield zone?
When a fastener is stretched into the yield zone, some of the elasticity is permanently lost, and the fastener will remain somewhat elongated when the load is removed. The further we stretch the fastener into the yield zone, the more elongation we get.
What are the two categories of threaded fasteners?
Threaded fasteners in an engine can be divided into two general categories: critical and non-critical.
What is the function of a fastener?
Fasteners function in an engine to hold parts together. For example, a rod bolt and nut hold the rod and cap together. Fasteners are also, in the case of head gaskets, used to load the gasket with the necessary force to seal the gasket under the forces of combustion as well as thermal expansion and contraction.
