Failure Analysis on Fracture of Silicone Oil Fan Clutch Shaft When Assembling

Fracture failure occurred to a silicone oil fan clutch shaft when assembling. Through macro analysis of the fractured shaft, it was found that the fracture originated from the hole at center of the shaft, and a hole was also found at bottom center of the unbroken shaft. The existence of internal holes of the shaft was further confirmed by metallographic examination method and the nature of the holes defects was analyzed. It was found that the early fracture of the shaft had direct relation with the serious internal casting shrinkage of the shaft. In addition, the abnormal coarse overheating microstructure exacerbated early fracture of the shaft. Finally, preventive and improvement measures were put forward according to the fracture reasons of the shaft.