| Guide to Bolts, Nuts and Washers |
Nuts, bolts and washers are used in all joinery work in domestic and industrial applications. Nuts are threaded holes that work with threaded bolts to fasten hardware. Bolts or screws are cylindrical rods having helical threads and a head; used standalone or with a bolt for positioning and fastening. Washers are thin, round plates of metal or plastic, with a hole for the fastener to go through.
Nuts and their types
Nuts and bolts hold together materials by forming a tight hold due to their interlocking threads, part compression and stretching of the bolt. Nuts and bolts are matched by their proof strength that is measured by the ISO property class. To circumvent loosening due to vibrations and torque, nuts can come with locking features such as nylon wires, adhesives, oval shaped threads, and so on. These nuts are called locknuts or prevailing torque nuts. They come in various shapes but the most common is hexagonal.
Common types of nuts:
- centerlock nut
- elliptical offset lock nut
- toplock nut
- tapered thread nut
Bolts and their types
A bolt is composed of a shank that is partially or fully threaded, and may or may not taper; and a head that is usually larger than the body of the bolt. Most bolts are driven into a material, but there are exceptions. Bolts usually have right handed threads, except where they can be subjected to anticlockwise forces.
Bolts are made of metals – stainless steel, alloys, titanium; or plastic – Teflon, nylon. The shape of screw heads varies – pan, button, round, truss, flat, oval, bugle, octagon, hexagon, cheese, fillister, mirror screw or headless. Drive designs on the screw heads also vary – single slot, cross-head, square, hex, Torx, Pozidriv, Supadriv, tri-wing, double hex, Bristol, combi-head drives and more.
Common types of bolts or screws are:
Washers and their types
Washers are used to distribute the load of a threaded fastener to prevent brinelling; for spacing; as spring and wear pads, locking devices, preload indicating devices; and for the prevention of galvanic corrosion. They come in various sizes.
Following are the main types of washers available:
Nuts, bolts and washers have a place in almost all mechanical, manufacturing and engineering processes. It is important to select the right fasteners and washers for the job as these simple pieces of metal or plastic play a vital role in reinforcing structures and materials.
