The upper mold and the lower mold constitute a complete mold. Take the profile extrusion die as an example. The upper mold is also called the female mold, which is used to shape the outer peripheral shape of the profile, and the lower mold is also called the male mold, which is used to shape the inner hole shape of the profile. In the case of a stamping die, the upper die is used for stamping and forming, and the lower die is used for fixing the workpiece. If it is a progressive stamping die, the lower die also has the job of guiding the material to advance.

Generally, the upper mold of the punching and blanking mold is installed with a convex mold, and the lower mold is installed with a concave mold. The function of the upper mold is to punch a piece of material on the plate to be stamped, and the function of the lower mold is to bear the pressure of the upper mold, so that the material to be stamped will not be deformed. The upper mold is equivalent to the upper blade of the scissors, and the lower mold is equivalent to the lower blade of the scissors. The upper and lower blades interact to cut the material.