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
| Type | RROC | RRO |
| Type |  |  |
| 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 |
