Basic Of Metal Stamping : Tools and Dies Fixed Stripper

Stripper Designs

Stamping dies require some means of stripping the part from the end of the punch at withdrawal. Common types of strippers for accomplishing this include Fixed, Urethane and Spring. Stripping force varies based on part material type and thickness as well as punch-to-matrix clearance. This force ranges from nearly zero to as much as 25% of the force required to perforate the initial hole. Most applications do not exceed 10% of the perforating force.

Fixed StripperFixed strippers go by many names:
. Box . Bridge
. Channel . Positive
. Solid . Tunnel
A fixed stripper is a steel plate with a clearance slot that allows the part material to pass under it. This plate mounts to the die  etainer in a fixed  position. Clearance holes cut through the stripper plate let the punches extend through without interference. At withdrawal the part material hits the stripper, preventing it from lifting as punches retract. The part material strips from the end of the punch.

 

Fixed strippers have several drawbacks. They do not hold the stock strip flat and are unable to absorb impact and snap-thru hock. The result is poor part flatness and premature punch failure.
We generally do not recommend fixed strippers for high-volume or highprecision jobs. A typical clearance under the stripper is 11.2 times the material thickness - 1/16h to 1/8h is common clearance on the sides of the stock strip.

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