An important factor in die design is Clearance. Punching holes and other cutting operations require specific and carefully maintained clearances between the punch (male component) and the die (female component). The setting of the required clearances is determined by both the stock thickness and temper. In general, die clearances increase as the stock thickness increases. The depth of punch penetration into the sheet metal stock will also increase as softer stock is used.
Some type of stripper is also required to make sure the part doesn't stick to the punch and ejector is sometimes used to make sure the slug doesn't stick to the end of the punch.
The ability to 3D model has taken much of the art out of die design but not all of it. The dynamics of stamping can never eliminate the experience a highly skilled tool designer can bring to the table. One tool that is frequently used to help under stand these dynamics is called "Circle Grid Analysis", or CGA.
The application of CGA involves the etching of a pattern of small circles on the surface of the blank. This pattern deforms along with the blank as it is formed, providing point-to-point calculations of the deformation that occurred. Analyzing this stamped grid pattern suggests the location and type of rework that must be performed on the dies to produce easily manufactured parts. The CGA process is repeated on the die until an acceptable part is produced.