Radiused Run-out and Die Material Selection

Functions of Radius Run-out

Since flat dies with sharp corners on the runout threads generate stress concentration areas that result in fatigue cracks on the thread rolled screw. With RRO/RROC, the smooth radius in the thread root continues to the point at which the thread blends in the screw shank. This radius distributes stresses evenly – increasing fatigue resistance in an area of the screw where failure is most likely to occur.

Radius Run-Out Process Selection

ReferenceIt is used on Aerospace, Automotive and high strength screw.If there’s no special requirement, it just removes the sharp edges of incomplete thread on the screw.

The Material of Rolling Die Selection

MaterialHeat TreatmentSurface TreatmentApplied Workpiece
DC53HRC61-62NitridingFor general low-carbon and medium carbon steel screws
SKH9HRC63-64NitridingFor High Strength Screws (Automotive parts), Stainless-Steel screws and after heat treatment screws

Thread Rolling Die Information

T.R.D. Size

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