Washers: Nuts and bolts work by placing a threaded shaft under tension
This tension, or preloading, is essential to strengthen the joint and reduce bolt fatigue due to fluctuating (variable) loads, as in the case of a machine part subject to vibration. If any of the parts involved deform under load--for example, if the contact area in the threads has any creep (or "plastic" flow), or any high spots on the contact surfaces between the threads flatten out, or the bolt or shaft lengthens microscopically, or the fastened parts compress, the joint will lose some of its tension.
Lock washers can help with this situation by applying a spring force against the nut or bolt head. Any stretching or flattening of parts is likely to be much less than the compression of the spring washer, so the fastener won't loose much. Wavy washers are another type of washer meant to apply spring force, but they're not widely used as the spring force tends to be relatively small. Belleville washers, often called "Belleville springs," are washers shaped like a shallow cone or dish. The shape of these washers allows them to exert a constant spring force on a joint, even if the bolt or joint has significant slip or stretch after initial tightening. Belleville washers are typically used in high-stress applications such as structural steel.
A humble flat washer is used for many purposes, the two most common proper purposes are:To distribute the pressure of the nut or bolt evenly over the part being secured, reducing the chance of damage thereto, andTo provide a smooth surface for the nut or bolt to bear on, making it less likely to loosen as a result of an uneven fastening surface.
The two most common improper uses of washers are: To allow the use of a bolt or nut too small for the hole in the part being secured or make it possible to tighten a bolt or nut that's too long.Using washers improperly can lead to damage or injury, so it's worth understanding how they're supposed to be used. Another use for a washer is to reduce the friction when tightening and loosening.
You can reach a greater tension on the bolt with a washer and when removing a bolt less torque is needed to break the bolt free from it tightened position Another use for a washer is to reduce the friction when tightening and loosening. You can reach a greater tension on the bolt with a washer and when removing a bolt less torque is needed to break the bolt free from it tightened position.
The most common reasons that cause loose tightness of nuts or bolts are corrosion in the threads, vibration or cyclic movement of the parts loose, and compression of the parts. Another use for a washer is to reduce the friction when tightening and loosening. You can reach a greater tension on the bolt with …
