First, the role of nuts and bolts
Nuts and bolts are common mechanical connectors, widely used in all walks of life, and their main role is to connect two or more parts together to complete the assembly or maintenance of the machine.
Second, what is the grade of bolts?
The grade of the bolt refers to the strength level of the bolt itself, usually expressed by numbers or letters, such as 4.8, 8.8, 10.9, 12.9 grades. The number represents 10 times the tensile strength of the material, and the letter indicates the hardness level of the bolt, such as 8.8 indicates that the tensile strength of the bolt material is 800N/mm², and the hardness level is 8. The higher the bolt grade, the greater the strength and the stronger the bearing capacity.
Third, what is the grade of the nut?
The grade of the nut is different from the bolt grade, which refers to the precision grade of the nut itself. The grade of the nut is generally expressed by numbers, such as 4, 5, 6, 8 grades. The larger the number, the higher the color of the nut and the higher the accuracy. The grade of the nut is only related to its manufacturing accuracy, and has nothing to do with its material quality.
Four, why the nut grade is lower than the bolt?
1. Material strength reasons
The bolt needs to withstand the action of tensile force, shear force, bending force and other forces, so its strength requirements are higher than the nut. The strength of the bolt is related to the strength of the material, while the strength of the nut is not directly related to the strength of the material. Therefore, the bolt grade of the same material will be higher than the nut grade.
2. Manufacturing process reasons
Manufacturing high-precision, high-volume nuts is more complicated than bolts and therefore more expensive. In contrast, the process of making bolts is simpler and less costly. Therefore, the grade of the bolt is higher than that of the nut.
V. Summary
In this paper, the reasons why the nut grade is lower than the bolt grade are analyzed, and the material strength and manufacturing technology are explained. We can see that the grades of nuts and bolts represent different meanings and cannot be directly compared. In actual use, it is necessary to select the appropriate bolts and nuts to ensure the firmness and safety of the connection.