1. Purposes of push back
a. push back keeps the flatness.
  ( this method reduces the bending moment than normal cutting's)
b. push back prevents a warp.
c. push back is used as a carrier (when nothing other way).
d. push back is able to push  burrs.

2. Checking points (We'd never fail to push back)
a. Clearance is less than normal cutting's.
b. Force of the knockout spring is strong enough.
c. The height of the knockout is equal to the push back die's level.
d. The face level of the cutting punch is same as the stripper face
   at the upper dead point. (see fig 1)

fig 1

e. We make waste blank usually.this carrier is useful as a spring (see fig 2)

fig 2

f. Timing of the guide lifter are same timing of the stripper-leaving up.
g. Pilot pins mustn't pull the stock up.
   (There are deep concern to the position of the guide lifter)
h. The stock will always have to be straight.
   (Include the range of inside and outside of dies) ( see fig3)

fig3

i. The stock must be straightened by leveler before it is in to the dies.
j. We must prevent from sticking by oil.

-It is impotant to make no rattling. --
--We should carry the blanked part well no dropping.-


 The other way
We stop the cutting punch near end of the stock thickness.(see fig4)

fig4

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