Types of Threaded Fastener

Types of Threaded Fastener

Threaded fasteners are used for a multitude of applications, which means although their function is a simple one – to hold components together – there is a wide variety of designs and sizes to choose from.
The most common threaded fastener types are screws, nuts, bolts and washers, although there also specialist types for specific fastening applications.

NUTS

Dome nuts, also known as cap nuts or acorn nuts, get their name from their shape. The domed top is designed to prevent contact with the external thread but is also sometimes used for aesthetic purposes as a cover for threaded rods or as caps for machine screws in metal work.
Flange serrated nuts have a wide flange at one end which acts as an integrated washer that does not move or spin. The serrated flange distributes the pressure of the nut over the part being secured, therefore creating a locking action to prevent loosening.
The hexagonal nylon hex nuts are internally threaded with a nylon insert. This material prevents loosening from vibration and cross threads to stop the nut from backing off of the fastener.
Wing nuts have wings on each side of the body which allows for manual turning and installation. This means they’re great for hand assembly and when the nut needs to be removed often.

BOLTS

Cup square bolts have a domed head with a square anti spin shoulder. These are mainly used for fastening timber or attaching ironmongery to timber.
Hollow steel bolts are designed as a fixing solution for connecting in a steel cavity, whether this is a hollow section of steelwork or where access is restricted to one side only. They are suitable for rectangular, square and circular hollow sections.
When joining metal to metal, roofing bolts are a great option but they’re also suitable for many other construction materials and applications including fitting cable trays and trunking.

SCREWS

Coach screws are heavy duty screws with a square or hexagonal head and an externally threaded cylindrical shaft that tapers to a point at the tip. They are primarily used for holding together heavy timber, fixing metal to timber, and in some cases masonry or concrete.
A machine screw can be either a screw or a bolt and has a flat point. As their name suggests, they are used to fasten various components together in machines, appliances, vehicles, electronic devices and tools.
Socket screws are useful for applications requiring a strong bolt or screw where access is limited. They are also known as Allen head screws or bolts, requiring a key to tighten and remove.

WASHERS

Flat washers are round outer diameter thin plates with a center hole punched to the size of the bolt or screw. Flat washers are used to distribute loads of threaded bolts, screws, and nuts evenly as the fastener is tightened.
Square washers may be flat on both sides or flat on one side and beveled on the other. These are often used in conjunction with square head bolts, preventing pull through and providing a larger surface area and greater hold than standard round washers.
Shakeproof washers, otherwise known as toothed lock washers, are used for locking and tension. They are round washers with internal teeth, designed to prevent a nut or screw head from loosening with the strut action created by the teeth.

THREADED ROD

There are also specialised threaded fasteners, which includes threaded rod. Threaded rod is used for fastening anything from an anchor bolt to suspending electrical or plumbing equipment from a ceiling.