冲切母模之形状设计应考量之要项有：A.模具寿命及逃角之形状，B.母模之剪角，C.母模之分割。
The key points to be considered in the shape design of punching mother die are: the shape of die life and escape angle, the shear angle of B mother die, and the division of C mother die.
（A）。模具寿命及逃角之形状：此设计是非常重要的事项，如设计不正确将会造成冲头之破损、冲屑之堵塞或浮上、毛边之发生等冲压加工不良现象。
(A). Die life and shape of escape angle: This design is very important. If the design is incorrect, the punch will be damaged, the chip will be blocked or floated, and the edge will occur.
（B）。母模之剪角：外形冲切时为减低其冲切力，母模可采剪角设计，剪角大时冲切力之减低亦大，但易造成制品之反曲及变形。
(B). Shear angle of the mother die: In order to reduce the punching force when the shape is punched, the mother die can adopt the design of shear angle. When the shear angle is large, the reduction of the punching force is also large, but it is easy to cause the reverse and deformation of the product.
（C）。母模之分割：母模必须施以成形研磨等精加工，由于其是凹形状，研磨工具不易进入，故必须加以分割。
(C). Mother die segmentation: Mother die must be processed by forming and grinding. Because of its concave shape, grinding tools are not easy to enter, so it must be segmented