A nut is a type of fastener with a threaded hole, used in conjunction with a threaded bolt, providing reliable fastening of multiple parts. This is accomplished by the tightening of the nut and bolt, resulting in a slight stretching of the bolt, causing a compression of the parts to be joined.
First to be manufactured was the square nut due to the ease of manufacturer, originally by hand. Today, the most common nut shape is the hexagon as a six sided nut allows multiple angles from which a tool to make contact, especially in tight spaces.
Nuts exist in a wide variety of designs, with many being highly engineered for an exact use and application; some engineered to a technical standard. Nuts and bolts used in industrial applications ae tightened to a specific torque (with a torque wrench). Lastly, nuts are graded with a strength rating compatible with their corresponding bolt.
Some of the most widely used nuts in the industrial marketplace include:
- Hexagon (Hex) Head: Six sided for use with various wrenches.
- Heavy Hex Nuts
- Structural Heavy Hex Nuts: Steel to steel structural connections
- Nylon Hex Jam Nuts: Hex nut with nylon insert that resists loosening
- Cap Nuts/Acorn Nut: Domed end on one side
- Square Nut: 4 sided providing greater resistance to loosening.
The most common materials for nuts are:
- Steel: Grades 2, 5, 8 and Alloy (Many of the steel grades can have Zinc or Hot Dipped Galvanized coatings.)
- Stainless: Type 304 & 316
- Bronze & Brass