In bolts and fasteners, flange nuts are specialized hex nuts with a wide circular flange on the bottom. They come in two main variants: flange lock nuts, which use prevailing torque to fasten, and serrated flange nuts, which grip the applied part using serrations on the bearing surface. They are suitable for use with oversized and irregular holes as the flange covers the gap. These nuts are used in garden equipment, automotive assembly, metal joinery, and other marine and industrial applications. Here is a guide for selecting the right kind of flange nut for a project.
Application and area
These two kinds of nuts use different mechanisms to fasten, and the areas that they can be applied to are limited by them. For starters, flange lock nuts use a deformed thread to create prevailing torque (a resistance to tightening) as they are fastened. So they can't be used to secure thick materials, as the nut needs to be fully engaged for the locking mechanism to work, and they are best not used with a long assembly, as forcing the nut over a long distance can damage the locking mechanism. For similar reasons, they can't be reused too much.
Serrated flange nuts, on the other hand, can be reused. These work by creating small distortions on the surface of the material the nut is applied to, creating a ratchet locking mechanism. Thus, it can't be used in situations where there is a protective coating on said material, as the distortions can make it vulnerable to corrosion around the joint. It also cannot be used with washers because the flange has to make contact with the surface.
Finishing and protection
Flange lock nuts are most commonly available in Grade 8 steel. They must be of the same hardness as the bolt, or the pressure exerted during installation may damage either or both of them. These lock nuts may have a finish of black phosphate and oil or yellow plated zinc. Both provide some degree of corrosion resistance, though the phosphate and oil offer added lubricity and the zinc better protection from rusting. Some flange lock nuts have a Nylon insert that sits tight against the fastener to prevent loosening.
Serrated flange nuts are available in zinc plated steel, which provides some protection, but if corrosion is a concern, stainless steel nuts are the best option by far.
Categories Simillar to Flange Nuts includes Coupling Nuts, Eye Nuts and Nut Inserts