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How are the bolts labeled?

Destini Fry
How are the bolts labeled?

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Whether in industrial or DIY situations at home, the use of screws is unavoidable. Unfortunately, the markings on them are not always legible, and even the clearest symbols are difficult for the uninitiated to decipher. While when assembling furniture in the instructions, all the pieces are numbered, making them easy to identify, when it comes to buying screws in a construction store, you need to know their markings. Learn about the various markings you can find on screws.

The grade of a screw – how is it marked?

The grade of a screw is its accuracy, or in other words, how it is made. This designation is expressed by the letters A, B or C. In this system, the A stands for the highest accuracy of the screw, or simply accurate class. Class B is medium accuracy, and a screw with a C designation is coarse, or poor quality. Depending on the application of the bolt, sometimes a low grade will not interfere with its use, but if it is to hold together important parts of a machine or expensive equipment, the only correct designation is Class A. Screws of different classes, in addition to accuracy, also differ in price, of course. Sometimes, however, it is not worth saving on materials if they are to play a key role in a given construction. Excellent quality screws, made of the best materials you can buy directly from the manufacturer in the online store

Strength and hardness of the screw

Another category, according to which the division of screws is carried out is their hardness and strength. They are expressed by numbers stamped on the head of the screw after the letter, indicating its accuracy class. The mechanical properties of a screw are its tensile strength and yield strength. A more ductile bolt is not suitable for connecting heavy parts and demanding structures, as it will deform and not hold the part as it should. The strength class indicates the upper limit of stress that the fastener can withstand, reacting by plastic deformation until the material breaks completely. Yield strength, on the other hand, is the least amount of stress it can withstand before it begins to deform plastically. The strength class must be matched to the type of construction that the fastener will be used for. Numbers which can be found on fastener markings are: 4.6, 4.8, 5.6, 5.8, 6.8, which are ordinary strength classes used for private purposes, and high strength classes: 8.8, 10.9, 12.9, used for industrial construction. Some strength classes are strictly connected with certain accuracy of workmanship. So, in classes A and B there are bolts with mechanical properties of 5.6, 8.8, 10.9, 12.9. In accuracy class C the most popular are the bolts with mechanical properties of 4.6 and 4.8. The higher the digits in the designation, the higher the strength of the bolt, which naturally entails the requirement for better workmanship of the component

Both the best mechanic and the do-it-yourselfer must be familiar with the markings on screws. This makes it possible to create durable and stable structures that can serve a person for years. Huge industrial machines and armchairs in your living room can use the same screws, but it is worth matching their class, strength and size to the application to avoid unnecessary malfunctions and paying too high a price for elements on which you can save a few zlotys

Main photo: Pixabay/

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