Nuts come in all shapes and sizes and a variety of styles to suit the type of fastening and material for the application. Their only use is to fasten two pieces together, such as two sheets of metal. Interestingly, nuts are the only fastener that must be used with another component to work.
There are four major types of nuts: Hex, wing, cap, and acorn. All of them are similar in the sense that they all have an internal thread and must be used with a threaded bolt or post to secure whatever material they are holding together. Let’s take a look at what makes these nuts different and the types of work for which each one is best suited.
Hex nuts as the classic nut everyone thinks of when someone mentions “nuts and bolts.” They can be threaded down flush with the top of the bolt or post or screwed down the entire length of it, leaving a section exposed above the nut. This feature enables it to be used in applications in which the materials being fastened may be of varying thickness or distances apart (for example, if something is being sandwiched between two pieces of metal). A hex nut has six sides and comes in a couple of sub-variations:
Nylon insert lock nut (nylock): this is a hex nut with a nylon insert that helps the nut stay tight in applications where vibration or some other force may encourage the nut to shake loose.
Jam nut: a jam nut is simply a shorter hex nut. Likewise, a nylon insert jam lock is a shorter nylock.
Wing nuts look similar to Mickey Mouse ears – featuring a rounded cap with two metal tabs, or “wings”, on either side that enable the nut to be tightened and loosened using just your fingers. Wing nuts are very popular for temporary fastening applications, such as holding machine or equipment covers closed; for components that need to be routinely put together and taken apart, such as temporary shipping containers; or for holding together two components that need to be adjustable for sizing or portability.
Cap nuts feature a smooth “dome” that provides more of a finished look to a product. Because they feature a closed top, they can be used only in situation in which the bolt or post does not protrude above the nut.
Acorn nuts are a variation of the cap nut. Acorn nuts feature essentially the same design as a cap nut, except an acorn nut has a rounded top that’s taller than a cap. It, too, is used only in applications in which the nut does not need to screw down the entire length of the bolt or post shaft.