# Screw types, characteristics and applications!

Do you know what is the main difference between self-tapping screws and ordinary screws? Do you know where to use each screw? In this article, we will show you how to use the screws correctly.

# Screw – Features

The screw is a piece in a conical or cylindrical shape, made of resistant materials such as metals, PVC, plastic, etc. The screw structure is made in a continuous spiral rod with openings along its external part and an upper base (head) for fixing (there are screws without head), which is adapted to various fixing tools such as screwdriver, Phillips , pozidriv, Torx, Allen, English, etc. The screw is used to fix or join two pieces that can be easily assembled and disassembled, being able to associate the use of nuts or through the combined effect of rotation and pressure.

# Screw – History

The screw has some different versions of its creation and one of these poses as the inventor, the Greek Arquitas de Taranto around 400 BC when he developed the screw to be used in presses for the extraction of olive oil from olives.

Another personality who developed applications to the screw was Arquimedes, when he developed the thread principle around 250 BC, using it in the construction of devices for the transport of water in irrigation.

Leonardo Da Vinci designed some machines for making screws, but it was only in 1568 that his drawings took shape when Jacques Besson, a French mathematician, developed the equipment.

# Types – Screw

The screws are differentiated because of the shape of the head, the thread, the stem and the type of drive of the object. Thus creating four different categories: through and non-through screws, captive screws and pressure screws:

• Stud screws: they have no head and have threads on both screw limits. This screw is used in structures that require constant assembly and disassembly.
• Through bolts: they cross the total area that will be fixed, passing through the point where there will be the connection. Through bolts require the use of nuts and washers, thus ensuring the firmness and stability of the joining of the parts.
• Non-through screws: they do not get through the place where they are being fixed, so there is no need for washers or nuts, but need an area that is prepared to receive it, that is, the place must have a support to the screw thread to be used.
• Pressure screws: ensures the fixation of objects only with the force used when tightening the screw.

# Self-tapping and common screw

Now that we’ve explained a little bit about the screw, let’s go to a simple screw tip. Self-tapping and common screws have the same function as fixing parts. However, the correct way to use the screws and screws is quite different.

The self-tapping screw, there is no need for a thread in the hole. To perform the fixing screw self atarraxaste first make a hole in guide with a drill and the thin part that desired to fix screw. When screwing the screw against the workpiece, the screw itself threads the workpiece.

Self-tapping screw, no need to thread in the hole.

This screw is mainly used on wood, but it can be used on any soft material like plastic or resin. In the case of metal, use the self-tapping screw only on very thin sheets, but care must be taken because when more tightening is necessary, the self-tapping screw ends up bursting the thread and is not properly fixed on the plate. use the self-tapping screw without the guide hole, but it is more difficult and this is only possible on soft materials such as wood.

The common screw, different from the self-tapping screw, needs a thread in the hole where it will be fixed. The common screw does not have a thin point like the self-tapping screw and the thread shape is different, which does not provide the possibility of self-tapping on the part being fastened.

To use the common screw we have two very common alternatives, the first alternative is to drill the hole with the drill in the approximate diameter of the screw and make a thread using a threaded male. The thread tap has the function of making internal threads in holes to thread screws. Generally made of tempered and ground high-speed steel with standard thread threads on its body.