Sems

Many fasteners are available as assemblies with captivated washers, collars, specialized stampings or other components. Engineered assemblies, which combine metal, plastic and other components into one subassembly, are also available. Captured washers improve productivity, eliminate lost, dropped or forgotten washers and simplify purchasing and inventory control.
Features
One piece screw and washer assembly
Able to provide a larger bearing surface area than a one piece cold formed part
Able to provide a screw and washer assembly with dissimilar material
Benefits
Easier and quicker production line assembly over a separate washer and screw
Combines two part numbers into one
Provides a more consistent torquetension relationship
Distributes the load over a large bearing surface reducing potential joint yielding