Fasteners and Fixings Methods of Tightening Threaded Bolts

The following article includes pertinent information that may cause you to reconsider what you thought you understood. The most important thing is to study with an open mind and be willing to revise your understanding if necessary.

The best time to learn about bolts is before you're in the thick of things. Wise readers will keep reading to earn some valuable bolts experience while it's still free.

When dealing with fasteners and fixings, such as threaded bolts, you may have found that you have a hard time when you are preloading. This is to be expected, especially if you don't understand how to tighten the bolts correctly. The problem is, if you don't tighten the threaded bolts the right way, you end up with a lot of scatter and a failed bolt. So how do you avoid these problems?

Tightening Your Threaded Bolts
If you want to prevent bolt failure and reduce scatter, you must understand how to correctly tighten the bolts. There are six popular methods for doing so, and each one can be used to control the preload.

    * Torque Control Tightening- With this method, the torque that is needed to tighten the bolt is either calculated or pre-determined with a chart. Torque control tightening overcomes the friction that is normally associated with bolt tightening and calculating the amount of pressure that will be placed on the threads.
    * Angle Control Tightening-This method involves the use of pre-determined angles that are used to tighten bolts.
    * Yield Control Tightening-Unlike other types of tightening for fasteners and fixings, this method is generally determined by feeling. You feel where the yield point is while you are tightening the bolt, which allows you to reduce the amount of friction and reduce scatter. Electronic methods have been developed to assimilate this process, and they involve sensors which determine the yield point.
    * Bolt Stretch Method-The bolt stretch method involves the use a hydraulic device that causes an extension of the threaded bolt. If the pressure on the hydraulic device accurately controlled, the preload of the bolt will be controlled.
    * Heat Tightening-With this method, the bolt is heated slowly either under fired, with the use of carbon elements, or with the use of a heating coil so it will expand. The nuts is placed using angle control, and as the bolt cools, it is forced to remain extended.
    * Tension Indicating Method-To correctly tighten threaded bolts, a number of different tension indicating methods can be used. In general, though, this method of tightening relies on the measurement of the extension of a bolt and bolts and washers that indicate how they should be loaded.

Now you can be a confident expert on bolts. OK, maybe not an expert. But you should have something to bring to the table next time you join a discussion on bolts.

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