1. Cracking may be due to internal residual stress after the Machine. The work piece is large and has
machine through throughout the work piece. If there is no loosening, residual stress
It may be the cause of cracking the top position. Because it is the thinnest position of the work piece.
2. Cracking at the corner groove tail hawk. It may be the result of a design value angle radius is too small.
When there is too much hard work and hard load. Therefore, the corner of the groove tail hawk is crack.