How do you calculate nut torque?
DETERMINING TORQUE 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 is nut factor K?
The nut factor, K, consolidates all factors that affect clamp load, many of which are difficult to quantify without mechanical testing. The nut factor is, in reality, a fudge factor, not derived from engineering principles, but arrived at experimentally to make the short-form equation valid.
How do you determine torque for tightening bolts?
The basic formula T = K x D x P stated earlier takes these factors into account and provides users with a starting point for establishing an initial target tightening torque.
What is K factor in bolt torque?
The K factor is used to account for the energy lost to friction and other factors during the tightening process. The generally accepted K factors for this calculation are: 0.20 for assemblies with dry threads (no lubrication) 0.15 for assemblies with lubricated threads.
Can you torque the bolt instead of the nut?
In many situations you can apply torque to either the nut or the bolt head. Both will result in a tight connection and neither will avoid breakage more often (that occurrence can be avoided through other means). In certain circumstances, however, you will need to torque one and not the other.
Does length of bolt affect torque?
Tightening torque is not influenced by the bolt length so easy to standardize. The Bolt efficiency will be low due to wide tolerance of the tension.
How do I stop my bolts from vibrating loose?
How to stop bolts from vibrating loose
- Nyloc nuts: Provide extra friction to the bolt joint by using a type of nut called a nyloc.
- Flanged nuts: These have a washer-like base to evenly distribute pressure.
- Spring washers: Also known as split or split lock washers.
How much torque does a 1/2 inch bolt have?
ASTM A449 / SAE Grade 5*
| Bolt Size | TPI | Tightening Torque (ft lbs) |
|---|---|---|
| Plain | ||
| 1⁄2 | 13 | 75 |
| 9⁄16 | 12 | 109 |
| 5⁄8 | 11 | 150 |
What is k-factor in a torque equation?
Once you determine your k-factor, you can plug it into the equation: This is your input torque from your torque wrench determined by your specified torque. D = nominal diameter (bolt diameter) of the fastener (in.)
Is k-factor the same as nut factor?
The terms “k-factor” and “nut factor” are interchangeable. However, k-factor (a.k.a. nut factor) is not the same as coefficient of friction or friction factor. Those are different methods for calculating torque value, which we’ll discuss later in this article. Why is K-Factor Important?
Why is torque the only method of measuring bolt tension?
When torque is the only method of measurement, a change in one element, such as thread lubricant, will modify the nut factor and therefore the clamp force developed on a bolted joint. This is because torque is not directly measuring bolt tension.
Why do PTFE bolts have a low k-factor?
As a result, you have to test every manufacturer’s methods. The k-factor for PTFE bolts is typically lower, since the nut has been over tapped to accommodate the coating. This means there will be less contact surface for the nut on a threaded fastener. Here’s an article that explains how it works.