One Station, One Operation, No Handling
A progressive die feeds a coil through a sequence of stations, each performing one operation, until a finished terminal leaves the end of the strip. The part is never handled between operations, so consistency comes from the tool rather than the operator, and cost per piece falls sharply with volume.
The station layout is designed with the part, because any feature that cannot be formed in the strip becomes a secondary operation, and that is where hidden cost appears.
Sequence That Protects Position
- Pilot and pierce: pilot holes are punched first and locate every following station, so error does not accumulate along the strip.
- Form and bend: bend radii at least one material thickness, with relief cuts so the material does not tear at the bend line.
- Coin and swage: contact faces coined to control the mating surface without removing material.
- Trim and cut off: separation in the last station, with the carrier designed to support the part until the cut completes.
- In die sensing: miss feed and short feed sensors stop the press before a damaged part is produced.
Burr Is a Failure Mode, Not a Cosmetic Issue
A burr on a 0.3 mm terminal jams a reel fed assembly machine. Burr height is held below five percent of material thickness on functional edges, verified with a profile projector, and die clearance is set per station because the optimum clearance changes with the local feature.
| Parameter | Range | Control |
|---|---|---|
| Strip thickness | 0.15 mm to 2.0 mm | Alloy and temper selected together |
| Burr height | Below 5 percent of thickness | Profile projector, per lot |
| Plating | Tin, silver, nickel, selective gold | Bend and tape adhesion, contact resistance |
| Part width | 2 mm to 80 mm | Multiple parts per strip when volume allows |
Choosing the Alloy
C11000 copper carries current but does not hold spring force. C26000 brass balances formability and conductivity. C5191 phosphor bronze retains contact pressure over many cycles, and C7025 copper nickel silicon survives elevated temperature without losing it. A hard temper that will not form is worse than a softer one that creeps, so alloy and temper are chosen together with the geometry.
Tooling Economics
Below roughly five thousand pieces a compound die or laser blanks with a secondary form is usually cheaper, and we quote both routes with the crossover stated. Above that, a progressive die pays back quickly. The tool belongs to the customer once paid for, and it can be transferred with the strip layout and setup sheet on request.
Strip layouts, station counts and plating options are described on the progressive die stamping page.
