Fasteners and Rivet Nut

Mechanical fasteners provide a clamping force between two pieces of material.There is a wide variety of kinds of rivet nut and various materials used to make them. There are threaded fasteners, non-threaded fasteners and special purpose fasteners.Rivet nutare the most common material used, although aluminum alloys, brass and nickel are amongst other metals used.Rivet nut have the advantage over steel of being much lighter, non-magnetic as well as more corrosion resistant fasteners. Nickel has the particular advantage of strength at high temperatures.

The role of rivet nuts

With a rivet nut, the clamping force holding the two pieces of material together is produced by a torque being applied to the fastener to stretch it as well as this is maintained during the service life of the fastener. The rivet nut is in tension and the two pieces of material in compression. Bolts mated with rivet nuts and screws with threads in the material are examples of this type of fastener. Low- or medium-carbon steel bolts will typically have a minimum proof strength of about 225 to 400 Pa, the proof strength being the maximum stress the bolt can withstand without acquiring a permanent set. For quenched and tempered mediumcarbon bolts the minimum proof stress is 600 to 650 MPa and quenched and tempered alloy steel about 970 MPa.Rivet nuts are especially useful for joining components that are likely to need to be dismounted during the life of the product.

The characteristics of the rivet nut

Rivet nuts, eyelets, nails and pins are instances of non-threaded fasteners.Rivet nut can be used for joining dissimilar or similar materials, both metallic and non-metallic, to give permanent joints. When the force applied to the rivet nut is adequately high, plastic deformation occurs and the shank of the rivet increases in diameter as its length decreases. That part of the shank within the hole increases in diameter until it fills the hole and the unsupported part of the shank outside the hole continues to deform until a head is formed. A ductile material has to be used for the rivet material, e.g. mild steel, copper, brass. aluminium alloy. For some materials the required ductility is obtained in the cold state, in other cases the riveting takes place hot. Where the riveting force might damage or distort the materials being joined, tubular or rivet nuts might be used instead of rivet nuts.