Acorn nuts, also known as cap nuts, are fasteners with a dome-shaped design that resembles an acorn. They are typically used to cover the exposed ends of threaded bolts or rods, providing a clean and finished look while also preventing the bolt from loosening due to vibrations. The shape of the nut provides a secure fit, and the closed end can prevent dirt and debris from entering the threads.

Acorn nuts are made from a variety of materials, including stainless steel, carbon steel, brass, and aluminum. Stainless steel is the most common due to its corrosion resistance and strength. Brass acorn nuts offer a decorative finish and are often used in aesthetic applications, while aluminum provides a lightweight alternative. The choice of material depends on the specific application and environmental conditions.

The key difference between acorn nuts and other types of nuts lies in their design. While traditional nuts have a hexagonal shape with an open end for threading onto a bolt, acorn nuts have a rounded, dome-shaped cap that covers the entire threaded area. This makes acorn nuts ideal for situations where the threads need to be shielded, such as in automotive or industrial settings. They also provide a more aesthetically pleasing finish.