Design for Manufacturing: Stamp Notching

This article provides instructions on when notching is required in stamping operations based on subsequent operations. Whenever a part must be contoured, several operations are required. If a bend is required, the part must first be notched. If the part was not notched first, the sheet metal would be far more likely to not pass quality inspection due to defects in the bending operation.

To properly position the notch, pilot holes are recommended. These pilot holes may be either internal pilot holes or external. After the bending operation, an idle operation should generally be used to maintain die strength. After the idle operation, the part may be separated from the strip.

If:
(a) While designing a product that will utilize sheet metal:
(b) If bending is required in such a way that the part is wiped across a form

Then:
(a) A notch operation must be performed before any wipe forming or bending operations.
(b) Notching may require separate workstations.
(c) Idle operations should proceed with the bending operation when practical
(d) The use of pilot holes to align notches is recommended
By following this rule, product designers will produce fewer contour-related defects in stamped sheet metal parts.