Glossary

A knurl on a fastener is a patterned ridge texture—usually straight, diamond (cross-hatched), or helical—formed by rolling or cutting the metal. It’s added to the shank, head, or flange to create friction or an interference fit so the part won’t rotate or pull out. You’ll see knurls on press-fit pins, self-clinching/press-in nuts and inserts (especially for plastics and soft metals), rivet nuts with anti-rotation bands, and on thumb screws/knobs where the pattern also improves finger grip.

Compared with under-head serrations (which lock under a bolt head), knurls are raised ridges that bite into a mating material along the surface they contact. The result is higher torque-to-turn resistance, better anti-rotation in plastics and aluminum, and more reliable retention without adhesives.

A knurled nut is a specialized fastener with a ridged or textured exterior surface—called knurling—that enhances grip for hand tightening and loosening without tools. Unlike conventional nuts that depend on wrenches or sockets, knurled nuts are designed for applications where quick adjustments, easy assembly, or frequent removal are needed. This makes them especially useful in settings where convenience and accessibility are prioritized over high clamping force.

In terms of design, knurled nuts are often cylindrical, but they can also take flanged or domed forms. The knurling pattern, which may be straight, cross-hatched, or diamond-shaped, is either machined or rolled into the nut’s surface to create a roughened grip. These nuts are produced in various materials—such as brass for conductivity, stainless steel for corrosion resistance, aluminum for lightweight strength, and plastic for cost efficiency or non-conductive applications—depending on the performance requirements of the assembly.

The purpose of a knurled nut is to enable secure fastening while still allowing tool-free operation. They are intended for low-torque applications where a firm hand grip is sufficient, making them ideal for adjustments, fine positioning, or parts that require frequent disassembly. Their hand-friendly design ensures users can easily operate them even in tight or delicate setups, where over-tightening with tools could cause damage.

Common applications include electronics, instrumentation, and machinery, where they secure panels, covers, or knobs. They are also prevalent in camera and lighting equipment, which often demand rapid hand adjustments, as well as in furniture assembly, consumer appliances, and clamping systems where tool-free operation is a key advantage.

Knurled nuts offer several benefits: they are simple to install and remove, provide excellent grip even with oily or wet hands, are available in multiple materials and finishes to suit specific uses, and eliminate the need for tools in many low-torque assemblies. However, they do have limitations. They are unsuitable for high-load or high-vibration environments, where the absence of strong clamping force can cause loosening. Over time, the textured edges can wear down, especially with frequent adjustments, and some designs are bulkier compared to standard nuts, making them less space-efficient.