Without such fasteners as screws and bolts, you can not do in any construction. For fastening various building structures, they are used everywhere. But how to understand where to use the bolt, and where is the screw? First of all, for this you need to know what these fasteners are.
Bolt and screw are called metal fasteners, fixing and connecting parts at one point. They can be used not only in construction, but also in the production of goods; they are responsible for connecting various mechanisms and structures. Interestingly, what is the difference between a bolt and a screw? Indeed, outwardly these products are very similar - made in the form of a metal rod with a thread and (most often) a head.
Difference between bolt and screw according to GOST
Standard interstate GOST 27017-86 "Fasteners. Terms and definitions, "in principle, should clarify what the difference between bolt and screw. To do this, you need to know more about the characteristics of each of the mounts, based on the standard.
What is a bolt?
From English, "bolt" is translated as "rod". According to GOST 27017-86:
A bolt is a fastener in the form of a rod with an external thread on one end, with a head on the other, forming a connection with a nut or threaded hole in one of the connected products.
Typically, the hexagonal tip has a bolt, although you can find it with a tetrahedral. The bolt is usually secured with a nut. A nut is a fastener having an internal thread. When working with bolts, washers are also often used. The washer, in turn, is a round product that is placed under the head of the bolt or under the nut, which allows you to increase the bearing surface or prevent them from unscrewing.
What is a screw
From the German gewinde comes the word "screw", it means "cutting, carving." By definition of GOST 27017-86:
A screw is a fastener for forming a connection or fixation, made in the form of a rod with an external thread at one end and a structural element for transmitting torque at the other.
A head with a slot for transmitting torque can be a structural element.
Two numbers mark each screw, for example, 4x30. The first number informs about the diameter of the screw under the head, measured in millimeters, the second - the length of the screw section (mm). For machine screws or metric screws that are used for metal, the rod diameter is constant in length. The screw can be screwed into the threaded hole drilled in the metal, or it can be passed into the through hole in the package of fastened parts, then a flat or spring washer is put on its end and the nut is screwed so that the parts are tightly pressed together.
The nut is marked with the letter M and marked with a number (from M1 to M68). The number indicates the diameter of the screw on which the nut intended for it will be screwed: for example, a nut marked M4 will only fit a screw with a diameter of 4 millimeters. Although it also happens that even if their diameter matches, the nut may not always be screwed onto the screw. This may be due to the fact that they have a different thread profile and pitch.
Differences
And yet, what is the difference between a bolt and a screw? The main differences include:
- How the parts are fixed: through the parts, the bolt passes completely, as a rule, and fastened with a nut (the threaded hole of the part is slightly less common), and the screw must be screwed into one of the parts that has a thread.
- Entry into the parts: scrolling inward, the screw fixes the parts, but the bolt does not do this, it remains static.
- Tools with which screwing occurs: the bolt is fastened with a wrench, and the screw, in the presence of a slot, can be screwed in with a screwdriver.
- As a result of joining two parts, some types of screws can rotate. They are used in moving and moving machine mechanisms, which a bolt cannot boast of.
- The bolt always has a head, the screw - often, but not always.
- Deepening: when screwing, the head goes deeper into the fastener, while in the bolt, it remains outside.
- At the screw, the thread is located along the entire length of the rod, at the bolt, it can reach half.
- The screws have a wider range of sizes than the bolts, since there are no small bolts, but there are screws.
- Disconnect the bolt connection by cutting the bolt, and the screw by cutting its thread.
- Strength: only tensile stress is taken into account when calculating screw connections, that is, to break the screw in the length of the axis, and when the bolts are calculated, both tensile and shear.
And then what is a screw and a screw?
Popular metal fasteners, in addition to bolts and screws, are screws and screws. They can be screwed into parts that do not have a prepared thread. What sets them apart from bolts and screws?
A self-tapping screw (a self-tapping screw is its full name) is a type of screw. Its difference lies in the fact that it forms a special thread in the hole of one of them in metal or plastic products to be joined.
A screw is a separate rod-shaped fastener. On the one hand, it has an external thread with a head, and on the other, a threaded conical end called a gimlet. When compounds are formed in plastic or wooden products, it serves for threading.
Having determined what the difference between the bolt, screw and other fasteners is, it will be easier to understand what and in which cases it will be best applied.