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
|Reference||It 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
|Material||Heat Treatment||Surface Treatment||Applied Workpiece|
|DC53||HRC61-62||Nitriding||For general low-carbon and medium carbon steel screws|
|SKH9||HRC63-64||Nitriding||For High Strength Screws (Automotive parts), Stainless-Steel screws and after heat treatment screws|