Shearing

Shearing

• Punch and die

• Ratio of rough area:burnished area increases with higher ductility

• Punch travel depends on the ductility or brittleness. – A brittle metal requires little travel.

Punch Force

• Punch Force = shear strength * cross-sectional area.

• Friction can affect this.

• P = 0.7 (UTS) (t) (L)

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Shearing Operation

• Punching – slug is discarded

• Blanking – slug is retained

• Fine blanking

• Slitting

Shearing Dies

• Clearance usually between 2% and 8% of the shear thickness.

• Compound dies– Several operations on the same strip may be

performed in one stroke.

• Progressive dies– Multiple operation are carried out as the coil is

moved after each stroke.