I have a copper ETP grade part 4mm thick. I am cutting it in a stamping die through cutoff operation. This is creating an angle over the thickness of the part which is not desirable. Though I know the cut off operation will create a taper over the edge due to process limitation, I want to reduce the taper.

I am adding a ref pic for better understanding. Kindly let me know what can be done to reduce the taper?