Consisting of a doughnut-shaped threaded hole, nuts are one of the most commonly used fasteners on the planet. They are typically used in conjunction with a bolt to secure two or more objects together. The bolt is placed through a pre-cut hole in the objects, after which a nut is placed on the end on the bolt. While all nuts feature this basic design, though, there are many different types of nuts. Below, you’ll learn more the different types of nuts and how they vary.
Acorn Nut
Also known as a cap nut, an acorn nut is a type of nut that’s characterized by a dome head. While other nuts are open on the top and bottom, acorn nuts are closed on the top. The top of an acorn nut resembles a dome, thereby restricting their usage to the very end of a bolt. Acorn nuts can not be twisted or otherwise installed farther down a bolt due to the presence of their dome-shaped head.
Knurled Nut
Also known as a thumb nut, a knurled nut is a type of nut that features a knurled exterior. In other words, it doesn’t have smooth edges as found in other nuts. Knurled nuts have rigid edges consisting of multiple vertical ridges. The purpose of this knurled exterior is to improve the ease at which the knurled nut is tightened or loosened by hand.
Square Nut
As the name suggests, a square nut is a type of nut featuring a square shape. Most nuts are shaped like a hexagon so that they can be installed or removed on a bolt using a wrench. Square nuts, on the other hand, are shaped like a square. So, what’s the purpose of their square shape? With a square shape, square nuts create contact with greater surface area, so they are less likely to loosen from vibrations.
Weld Nut
One of the most unique types of nuts is a weld nut. Weld nuts still consist of a threaded hole, but they are designed specifically for welding applications. The weld nut is first twisted onto the bolt, after which it’s welded in the place.
Barrel Nut
Also known as a dowel nut, a barrel nut is a type of nut featuring the shape of a barrel. It’s used extensively in household furniture as well as aerospace components. With their barrel shape, barrel nuts don’t have to be machined or welded into place.