Generally speaking, the gasket has two functions. One of the functions is to protect the surface of the connected parts from friction damage by the nut. Another function is to disperse the pressure of the nut on the connected parts.
Flat Washers
When the bolts need to be disassembled frequently, in order to protect the surface of the connected parts from being scratched, it is generally necessary to place a flat washer at the position of the nut or bolt head, so as to prevent the surface of the connecting parts from being scratched.
In the bolted connection, the pressure transmission of the bolt head or the nut-bearing surface is gradually expanded in a trumpet shape. The larger the bearing surface, the smaller the compressive stress. Therefore, adding a flat washer can reduce the compressive stress on the contact surface of the connected parts and ensure the effectiveness of the bolted connection.
Spring Washers
The main purpose of the spring washer is to relax, and it is generally used on occasions where the bolt pre-tightening force is not high and the dynamic load is small. In fact, the spring washer has a little anti-loosening effect. Therefore, for the tightening occasion with a relatively high pre-tightening force and the connection is more important, the spring washer is not recommended.
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