Case Study 5
Part name: M73 frame
Material: cold-rolled steel or 6061 aluminum
With this many punches, if the die went out of time because the material misfed, or because a pilot punch broke, or because the pilot distorted the hole used for location, the resulting breakage of punches would be very expensive; to avoid this, we used an extremely accurate CNC servofeed.
Secondary operations included forming a bearing race, which required an excellent surface finish; this was accomplished in the steel frame by forming the ball race after plating, and with the use of a high-pressure forming liquid. Another secondary operation necessary on some frames was a 90 degree bend; this was a challenge in 6061 aluminum, which has a tendency to fracture under severe forms. This was avoided by heating the workpiece just before it entered the forming die, which used a camming action to create the form, minimizing shearing forces within the material.
Other secondary operations performed on various members of this family of parts included tapping, engraving, and bead-blasting, all of which were done in-house. Some part numbers required as many as eight secondary operations.