Sometimes we put a small flat washer on the bottom of the nut when tightening the nut. This small flat washer is the so-called "washer". So why would you choose to put a washer under the nut?
First, washers can help spread the torque load on the nut. If you tighten the nut directly, you may cause uneven torque, causing the nut to not tightly grip the component being tightened. If the washer is on the bottom of the nut, it will spread the torque evenly and ensure that the nut holds the component tightly in the correct position.
Additionally, washers can help reduce friction and wear. When the nut is tightened, the washer prevents the nut from directly contacting the surface of the fastened component, thereby reducing contact forces and wear between the surfaces.
In summary, using washers improves the reliability and safety of fasteners and also extends their service life. Therefore, it is very important to use washers when tightening nuts.