1. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS by Peter Laczko

2. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Fatigue failure of shafts at interference fitted hubs, gears and support rollers.
Fretting due to microscopic relative movement within the elastic deformation range of the shaft.
Relative movement caused by cyclic bending or torsional stress of the shaft, and large disparity of stiffness between the shaft and fitted component.
Main examples used in this talk are kiln or drier trommel support rollers.
Other common examples are conveyor pulley drive shaft couplings.
Increasing use of keyless interference fitted couplings and output gears

3. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Typical interference fitted hub or roller. Interference fit ” per inch diameter.

4. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

5. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

6. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
FATIGUE INITIATION AT OD

7. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
FRETTING AND CORROSION PRODUCT

8. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

9. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

10. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

11. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Crack detected by UT. This section removed by boring out the shaft and leaving OD intact, then shrunk by internal welding.

12. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

13. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

14. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Region of relative movement and fretting at the ends of the interference fitted portion.

15. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

16. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS

17. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Fatigue fracture surface and projected depth of the crack.

18. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Micrograph showing one of the shallow cracks. X50

19. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Micrograph showing one of the shallow cracks. X600

20. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
Micrograph showing crack tip. X600

21. FRETTING FATIGUE OF INTERFERENCE FITTED SHAFTS
One method used to reduce stiffness of the hub.