Nut proof loading assemblies are designed for proof loading or cone stripping of threaded nuts. They are designed to be used in conjunction with fastener holders and are available for all of the fastener holders series.
Nut proof loading assemblies consist of a hardened proof loading mandrel and a proof loading plain flat washer. When used to perform cone stripping tests, an additional conically shaped plain washer must be used.
Nut proof loading assemblies are designed for a particular thread diameter and pitch, the mandrel stud is made of heat treated tool steel and is built for extended usage. The plain washer used for proof loading and the cone stripping conical washer used for cone proof loading are both hardened washers designed to ASTM guidelines.
Principle of Operation
Nut proof mandrel studs are mounted in a matching fastener holder exactly as a fastener under test. The larger end of the mandrel is threaded, and a matching plain threaded flat washer is seated in the recess of the fastener holder to hold the stud. This allows the force applied to the fastener holder to be transferred to the stud.
The other end of the mandrel is matched to the thread and pitch of the nut under test. A plain flat washer is slipped over the stud before threading on the nut. The plain flat washer's inner diameter is a close tolerance fit to the mandrel stud, and the outside diameter is the same as the recess in the fastener holder being used.
It is very simple for the user to switch from proof loading bolts to proof loading nuts without changing the fixturing which saves time and increases operator productivity.