Progressive dies allow a stamper to produce a finished part (in most cases) off one tool by incorporating many operations within the same tool. These operations can include notching, punching, coining, forming, tapping, bending and even assembly in some cases.
An automatic feeding system pushes or pulls a strip of material from a coil through all the stations of a progressive die. The part is carried from station to station attached to a carrier strip. At each station the part is accurately positioned so that a particular feature may be added. In the final station, the finished part is cut away from the carrier strip. The web of material left and any punchings from previous stations become the scrap.
Progressive dies are put into power presses that move vertically. As the press goes up the top of the die goes up, and the material advances from one station to the next. Each station is spaced exactly (within fractions of a thousandth of an inch) the same distance apart and the feed is set and pilots are used to advance the material the exact same distance with each progression. Then the press comes down, the die closes, and each station performs the stamping operation. With each stroke a finished part comes off the end of the die.
The cost is determined primarily by the size of the part, number of features (punchings, bends, forms, etc) required, the difficulty of features required, and the accuracy (tolerances) required on the finished part. Generally the closer the tolerances needed, the more expensive the tool is.