How to use flat washer and spring washer correctly？

In the process of installation of fasteners such as screws and stainless steel screws, accessories such as washers and flat washers are often used. In the actual application of fasteners, under what circumstances do flat washers and spring washers need to be used?

First of all, we need to understand the working principle of flat pads and spring pads.

1: The role of the gasket is generally to increase the contact area with the connected parts to reduce the pressure of the nut head on the workpiece surface.

2: The function of the spring washer is to prevent loosening. The elastic force generated by the compression spring washer and the edge of the notch of the spring washer are clamped to the connection surface to prevent the nut from loosening.

Therefore, if there is a requirement for the connection surface in the application process, or if it is not allowed to draw the device, a flat pad is required to increase the contact area and prevent the contact surface from being scratched by, for example, a spring washer. For example, when the hole diameter of the through hole of the bolt is large, the contact area of ​​the spring washer becomes smaller, and a flat pad can be added in order to increase the contact area. In the case where it is necessary to prevent looseness and often disassemble, it is necessary to add a spring washer to prevent loosening of the link. However, it should be noted that spring washers must not be used to prevent loose bolts when high-strength bolts are connected, because high-strength bolts require pre-tightening when tightening, so they cannot be prevented from loosening with spring washers. Generally, double nuts are used to prevent loosening, and torque wrenches are used to perform torque when tightening. After tightening, draw a noticeable line with a white oily stroke on the double nuts so that the nuts can be quickly checked out with eyes after loosening. .