A Bolt is an important fastener usually made of different metals such as regular grades and stainless steel and come with different plating of zinc, hot-dip galvanized, etc. These are not only available in different material grades but also with different heads. Yes, it's true that the head of each and every bolt is not the same. However, its head is the important factor that helps to identify its type easily. Lack of knowledge about their head may confuse the buyer and to make the selection and identification easier, here we highlighted some of the common types of bolt heads that you should know to make a wise decision. So, let's get started.

Pan Head Bolt: These are slightly curved with a very low, large diameter and high outer edge. You can easily tranquil it with the help of appropriate tools. These are very popular and widely demanded than the truss, round or binding heads.
Truss Head Bolt: These are the one that has an extra wide peak and slight rounded surface or top. These are most probably used in securing thin membrane. Moreover, these are ideal to use with any of the material that has large diameter holes.
Round Head Bolt: These are used in wood coections are mostly get confused with the carriage DIN934 hex nut . They have great strength to maintain a better grip on the application, it is joint with. It's a universally used design that has great demand in the market than any other of its kind.
Oval Heads Bolt: These are probably used in all such applications that require a fine finish and glossy surface. These are designed to fit perfectly in the counter bored holes and work well with aluminum and soft plastics. Because of their smooth surface, they also considered as Flat Head Bolt.
Hexagon Head Bolt: These may usually have six heads and probably get used in a tapped hole. These are perfect to use in construction, repairs as well as automotive projects.
Binding Head Bolt: It looks like the pan head bolt but the only difference is that it has a thicker head with a deeper slot. These are ideal to use in any kind of radio and electric work.

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 hexagonal nut , 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.