Progressive Blanking Dies
- Blanking dies are usually thought of as the simplest type. Basically, it consists of a pierce punch and pilot to establish the progression, possibly some additional piercing and slotting and a blank through or cut off at the end of the tool.
- When using a scrap chopper at the end of the tool, it must be encased in sheet metal to prevent injury.
- The thicker the metal, the smaller the pilot must be. This is due to the phenomenon of strip growth. For example, a part that is .125 thick may require a pilot that is .004 smaller than the pierced hole in order to run the die. Having a pilot .001 smaller than the pierced hole is great in theory, but the tool will never run consistently. This is also the reason it is very difficult to produce a part to nominal. The thinner the metal the metal the closer the diameter of the pilot can be to the pierced size. Another option is to use conical shaped spring loaded pilots that are larger than the hole.
- All pilots should be heavily spring loaded in case of a miss hit. When spring loading pilots, a hardened retainer may be required. This should be done for all high production dies. Utilizing ball cage die sets is also an advantage in both precision and die maintenance.
- Slug retention is also an excellent attribute for any tool.
- Multiple part dies take relatively a little more time to build, but afford great advantages. They are balanced tools that are easier to run. They double production rates, and can reduce material costs at the same time.
- Stamping lubricants and special applicators can have a major impact on production and quality.
- Normally, steel coil is used for production but it is not unusual to utilize steel strip for certain applications.
- In higher production applications electronic gaging, vision systems and attribute gages should be utilized.