Nuts, manufactured from various metals and plastic, are a type of fastener with a threaded hole. They are almost exclusively used to mate with a bolt that has the correct threading pattern.
The friction of the bolt and nut threads against one another creates a temporary joint that holds material together.
In Vipa nuts are available in different sizes and shapes for a wide range of purposes.
Most nuts are installed with a wrench, socket whereas others are applied without tools, by hand or may have special designs to prevent loosening.
In applications where vibration may provoke a nut loose, various locking mechanisms can be employed to maintain the nut locking the thread.
Those include plastic inserts, pins, special adhesive thread-locking fluid, lockwires, etc.
Otherwise, the use of lock nuts can add an extra tension to an assembly to prevent accidental loosening of components.
Nuts are available in the full range of metric threads, coarse and fine, and materials include carbon steels, high-tensile steels, stainless steels, brass, bronze, aluminium and nylon.
Hexagon nuts are the most commonly used fastener paired with a bolt or a screw. DIN 934 is the dominant standard even though new ISO Standard has introduced a new class of nuts that is similar to DIN 934, just slightly larger, for applications requiring a higher clamp load.
Hexagon nuts are available in various diameters from M1.6 to M64 and classes 6, 8, 10 and 12.
Regarding the materials, in Vipa are available hex nut in carbon steel, stainless steel A2 / A4, and brass.
Thin Hexagon nuts
Thin Hex nuts are nuts with a reduced height that are used in combination with normal hex nut to prevent the fastening system to loose. According the correct assembly method, the thin nut has to be applied first. Then, is necessary to lock the hex nut against it.
The two nuts when are tightened against each other, form a joint that prevent the normal hex nut from loosening, locking the thread. The international reference standards for thin hex nuts is DIN 936. Alike hex nuts, the ISO standard is slightly different for mechanicals performances and sizes.
Analogously Hex nuts, also thin hexagon nuts are manufactured from carbon steel, inox steel A2/A4, brass with different property classes.
Nylon insert lock nuts
Self-locking hex nuts are provided by a nylon ring placed at the end of the nut with an inner diameter slightly smaller than the major diameter of the screw. When a bolt or screw is tightened into the nut the nylon insert deforms elastically over the thread of the screw, thus locking the nut by friction against the screw. This kind of nuts are designed to be resistant to vibration.
The main international standards for nylon insert lock nuts are DIN 982 (nylon insert high hex lock nuts) and DIN 985 (nylon insert thin hex lock nuts) and regarding materials they are manufactured from carbon steel and inox steel.
Hexagonal flanged nuts
Flange nuts are nuts with a wide flange at one end that acts as an integrated washer spreading the load over the surface of the part that has to be secured. This kind of nuts reduces the chance of damage to the part, while preventing the thread to loose.
The underside of the flange is normally plain but can also be provided of radial serrations that inhibit the nut from rotating and unscrewing, thus maintaining the holding power of nut.
DIN 6923 is the international reference standard for Hexagonal flanged nuts.
Hex dome cap nuts
Hex dome nuts, also known as acorn nuts, are nuts provided by a domed end on one side.
They have a huge variety of uses. For example, they are largely employed as a cover for threaded rods and as caps for machine screws and, in more general terms, when a tidy good-looking finish is required.
Moreover, when Hex dome cap nuts are coupled with a threaded fastener, supplied of an external male thread, the domed end encloses any excess thread that would normally protrude past the end of the nut. That allows to protect either the thread and nearby objects from any accidental contact.
Acorn nuts are made of brass, steel, and stainless steel A2 / A4.
Castle hex nuts
Used primarily as safety nuts, to prevent loosening of an assembly, castle hex nuts are slotted to receive a cotter pin or wire which passes through a drilled hole in the bolt and locks it.
Reference standards are DIN 935 (standard castle hex nuts) and DIN 937 (thin castle hex nuts).
Heavy Hex nuts
Heavy hex nuts are slightly larger and thicker than standard hex nuts. This kind of nuts are available in different grades and are typically used for large diameter and high strength bolts.
Wing nuts are characterized by two metal wings, one on each side, so that they can be easily tightened and loosened by hand without any wrench. The ease of use makes wing nuts suitable for applications in which quick assembly / disassembly is the main feature required for fasteners.
Extension nuts (also known as coupling nuts) are hexagonal shaped nuts with an extended body, fully threaded. They are mainly used with threaded rod in a variety of applications: from leveling, to spacing, to joining two or more studs.
Extension nuts with left-handed threads are used to make up long rod assemblies from shorter lengths of rods whereas if they are threaded with two different thread sizes and profiles are called reducing coupling nuts.
A weld nut is a special type of nut specifically designed to be welded to another piece of metal. These can be used in place of sheet metals screws in thin sheet metal applications.
Albeit this kind of nuts have been generally replaced hex nuts they maintain a certain value due to their shape that provides better performances in terms of fastening.
Cage nuts consist in a low strength square nut wrapped in a spring steel cage that can be slotted into a punched hole. The main advantage of this kind of nut is to allow the cage to be located on the underside of a metal part. That, make then possible the screws to tighten the nut from the top side, without the need to hold it.
The nuts fit loosely in the cage allowing for some movement to assist the assembly and adjustment of the screw.
Palmuttern exagonal self locking counter nuts
Pal exagonal self locking counter nuts are a stamped nuts made from sheet metal which act as a resilient spring enabling a lightweight vibration-proof locking action.
They are designed to fit over a normal hex nut and lock it into place by using a series of protruding flanges that grip the host nut securely. That makes them suitable for applications where frequent load changes would tend to loosen standard hex nuts.