Nuts made from various metals and plastics play a primary role in a threaded assembly, acting as a device through which stress is turned pnto a fasteners shank and pairing parts, and continues to maintain that tension load in the assembly. Most nuts have hexagonal faces, but they are equipped with many other functions for secondary purposes such as thread locking, sealing, load sharing, clamping, welding and leveling.
A nut is a type of fastener with a threaded hole. Nuts are almost always used to connect multiple parts with a matching bolt. The two components are held together by a combination of the friction of their threads (with a slight elastic deformation), a slight elongation of the bolt, and the compression of the parts held together. In applications where vibration or rotation may cause the nut to loosen, a variety of locking mechanisms can be used: lock washers, lock nuts, double nuts, thread locking adhesive such as Loctite, latch (cotter pins) or wire lock In combination with castle nuts, nylon inserts (nyloc beads) or slightly oval threads.
Square nuts, including bolt heads, were the first to be made and were the most common, mainly because they were much easier to make, especially by hand. While now hex nuts are rarely preferred for the following reasons, they are sometimes used in certain situations where maximum torque and traction are required for a given size: Each of the wrenches longer lengths are allowed on the sides. With a larger surface area, there is more leverage on the nut.
The most common shape today is the hexagon (6 sides), for the same reasons as the screw head, create good grip quality on tool/ fastener corners and are good in tight spaces). Therefore, polygons (shapes/ forms with vertices/ corners) with more than six sides do not have sufficient grip. Polygons (e.g. square) with fewer than six sides take longer to complete their rotation when access is limited.
There are other special shapes for specific needs, such as wing nuts for finger adjustments and captive nuts for tight access areas e.g. chanel/ sliding housings
- Aerotight Nuts
- Castle Nuts
- Dome Nuts
- Full Nuts Lock/ Half/ Thin Nuts
- Nyloc Nuts
- Philidas Nuts
- Plain Non Serrated Flange Nuts
- Serrated Flange Nuts
- Wing Nuts
Aerotight all-metal self-locking nuts were originally designed and sold through GKN (British multinational automotive and aerospace components) in the 1950's a whole range is now produced and distributed by the BUFAB owned company. Aerotight nuts are also referred to as bent beam nuts and stiff nuts.
Castle/ Castellated nuts are hexagonal nuts with slots at the top that makes the nut resemble the battlements of a castle. These slots provide a substantial lock when used with a split pin.
Hexagonal dome nuts are also called acorn hex nuts beads because the head is shaped rounded like and acord from an oak tree. They are also known as round nuts, blind nuts and crown nuts. The nut is made in one piece with a cap at one end and is generally available in stainless steel, carbon steel, nylon and brass.
The advantages of the domed nut are that they act as a barrier to contaminants onto the threads which could shorten the joints lifespan, leading to premature failure. The end cap can also protect the joint from collision damage or snagging from the exposed thread. Aesthetically, the rounded finish of the cap creates a cleaner appearance of the product. They come in low or high options, depending on how much you need to reduce the profile that protrudes from the component.
A locknut/ half nut/ locking nut is tightened behind another nut as an extra precaution to prevent a fastening from loosening due to vibrations and/ or torque. The correct installation it to fasten the half nut first, followed by the other, tightened up behind to lock the thread. These nuts are approximately half the thickness of a full nut. They are called Jam nuts in U.S.
A nyloc nut is a nut that locks in a sense or is self-sticking and is less likely to loosen due to vibrations or stress. This is achieved through the addition of the nylon insert that has a diameter slightly smaller than the nuts’ thread. A fastener screwed into the nut cuts a thread into the plastic, therefore increasing the compression around it (tighter join). A nyloc nut is effective up to 121°C.
Philidas, all metal locking nuts, lock on a bolt or screw using a deflected/ skewed beam of thread, designed to create a more practical and reliable fastening method. Philidas lock nuts are mostly found in the aerospace, automotive and rail markets. Even in high-performance environments where vibration may occur, Philidas prevailing torque, self-locking nuts will remain in place.
Plain flange nuts are nuts with an enlarged base that acts as a built in washer. It is a hexagon nut with an exaggerated flange, which is unserrated.
Flange nuts are nuts with an enlarged base that acts as a built in washer. On the underside there are serrations (bumps) that will slightly deform/ indent the fastened material and therefore, ‘lock,’ it in place.
These nuts are used to provide a threaded socket in wood. To install them, simply tap the nuts into a suitably sized hole and the prongs will hold them in position. They used in wood and plastic applications. The 4 prongs give grip into the material. The nut sits almost completely flush, and provides a threaded insert. They are commonly used in furniture making.
Wingnuts have 2 large flanges on opposite sides of the nut (wings). One might say their profile is the same as Ben Ball’s, head shadow. They are fastened with finger adjustment and used in light duty applications where the nut is frequently removed or for hard to reach areas or situations where the stress/ torque requirements are low.