The weld nut is a special nut manufactured to be welded to another object or piece of steel. Offered in many different styles and designs, each weld nut is intended to perform a particular function under a given set of parameters. One of the differences between a weld nut and a common nut is the added material when compared to a typical nut. The added material allows the weld nut to be welded to another piece of steel while retaining its shape and size. Often when welding a common nut to a steel piece, the nut will be melted away and left too thin in some areas.
Some types of weld nut are intended to be used inside a channel or hollow square tube. This not only gives added strength to the channel or tubing, but it provides a mounting point for added accessories in areas that have no access to the rear side. This makes it possible to tighten and remove the part with only one wrench. It also ensures that the part will be mounted at the exact same location with no variation stemming from a slipped bolt. This also allows a mechanic to perform repairs without the need for a helper to hold the back side of a bolt when tightening or loosening it.
When a length of tubing needs to have threads in both ends to attach joints or other fasteners, a tube-end type of weld nut is placed into each end of the hollow tubing and welded into position. This allows each end to be threaded onto a component and fastened in place. This type of construction is widely used in automobile chassis design, in the shifting and throttle linkage as well as strut and bracing manufacturing. This procedure is much less costly when compared to actually threading the entire length of tubing. It also provides greater strength than cutting material out of the entire length of tubing to add threads.
In an effort to speed up assembly as well as to save time and money, many manufacturers have begun using retainer weld nuts on the assembly line. This type of weld nut has a flange that is welded to a steel component along with a floating or moving nut attached to the flange. This allows the nut to be positioned in many different configurations to compensate for assembly line inconsistencies and variations. Having this type of weld nut allows for plus and minus tolerances in assembly line manufacturing.