Progressive Die Stamping
Also: progressive stamping, prog die, progressive die, coil-fed stamping, high-speed stamping, multi-station stamping, prog stamping
Progressive die stamping feeds coil through a multi-station die that cuts and forms a little at every stroke; finished parts drop out at hundreds per minute.
39 shops tagged Progressive die among 1,023 metal stamping companies in the Noramark directory
A progressive die is a row of stations in one die set. Coil is straightened and fed a fixed pitch each stroke; the first stations pierce pilot holes that locate the strip from then on, later stations pierce, notch, bend, emboss, coin and draw, and the last station cuts the finished part free of the carrier strip. Every stroke advances every part one station, so a part with twelve operations still comes out once per stroke. Presses run 30-300 strokes per minute for brackets and 600-1,500 for small terminals.
The die is the investment: $30,000-250,000 and more, with 8-20 weeks to build, tryout and qualify. In return the part cost is material plus a few seconds of press time, features stay within ±0.05 mm (±0.002") of each other because the pilots locate every station the same way, and a single press with one operator makes a year of parts in days. In-die tapping, in-die welding of nuts and in-die assembly are common in high-volume work.
Progressive dies suit parts that can be carried by the strip: flat and shallow-formed parts with features that can be reached from above or below. Deep draws, forms that must be made at right angles to the strip, and parts too large for a carrier go to a transfer press, where fingers move free blanks from station to station. Design changes after the die is built are expensive, so the design must be frozen first.
At a glance
| Typical tolerances | Pierced holes ±0.025-0.05 mm (±0.001-0.002"); blanked profiles ±0.05 mm (±0.002") within one station; station-to-station position ±0.05 mm (±0.002") through the pilots. Formed features ±0.1-0.25 mm (±0.004-0.010") standard, ±0.05 mm (±0.002") with care and coining. Small terminals in carbide dies reach ±0.013 mm (±0.0005"). Tolerances loosen as the die wears; sharpening intervals are part of the process plan. |
|---|---|
| Size limits | Coil widths 10-400 mm (0.4-16") and thicknesses 0.1-4 mm (0.004-0.160"), with most work under 2.5 mm (0.100"). Parts from a few millimeters (connector pins) to about 400 mm (16") long, set by the press bed and the die length; large parts run on 600-1,500 ton presses with dies up to 2 m long. Form height is limited by the press stroke and the strip lift. |
| Surface finish | As-coil surfaces (about 1-2 µm Ra, 40-80 µin, on cold-rolled steel) with die contact marks where the strip is formed, cut edges with the usual rollover, burnish and fracture zones, and a burr on the die side. Carrier tabs leave a small witness where the part is cut free. Tumbling deburrs; zinc plating, e-coat and powder coat follow; connectors are reel-to-reel plated with tin, nickel or gold. |
| Lead time | Die design and build 8-16 weeks, up to 20 or more for large or carbide tools; tryout and PPAP 2-4 weeks. Production runs are scheduled in days once the die is qualified, usually against annual releases. |
Typical of U.S. job shops; confirm with the shop for your part.
Materials
Whatever comes on a coil in a formable temper: low-carbon steel (1008/1010), HSLA (A572 Grade 50, A1011), galvanized and pre-painted steel, spring steel (1095, 1074, 1050) for clips, stainless 301, 304, 316 and 410, aluminum 3003, 5052 and 6061-O, brass C260, copper C110, beryllium copper C172 and phosphor bronze for connectors. Electronics stampers run pre-plated (tin, nickel) strip and selectively plate reel-to-reel afterwards. Plate, castings, tool steels and hardened stock are not progressive-die materials.
What drives the cost
- Die build: number of stations, carbide versus tool steel, cams, in-die operations
- Annual and lifetime volume, which the die is amortized across
- Material: strip price and the scrap fraction the strip layout and carrier leave
- Press size and speed the part needs
- Part complexity: forms at right angles to the strip need cam stations
- Tolerances and cosmetic requirements that slow the press or add coining
- Secondary operations: plating, heat treating, tapping, assembly, reel packaging
When to use it
- Volumes above 50,000-100,000 a year, or 25,000 with a long product life
- Small and medium flat or shallow-formed parts: brackets, clips, terminals, shields, contacts, lead frames
- Parts with many features that must stay in position to ±0.05 mm (±0.002")
- Products that need in-die tapping, nut welding or reel-to-reel plating
When not to
- Under about 10,000 pieces a year: single-station dies or laser cutting and bending
- Deep cups and tall forms: deep drawing on a transfer press
- Parts wider than the coil or too heavy for a carrier strip
- Designs that are still changing
- Thick plate or machined features
Design tips
- Keep features in the plane of the strip or bent up from it; forms at right angles to the strip need cams and extra stations.
- Allow a carrier: the part needs an edge or tab where it can hang from the strip until the last station, and that tab leaves a witness.
- Hold one material thickness, hole diameters of at least 1t, and hole-to-edge distances of at least 1.5t.
- Use one inside bend radius (1t) and state the grain direction if a tight bend matters.
- Say which side the burr may face and whether the part will be tumbled, plated or used as stamped.
- Freeze the design before the die is built and prove it with laser-cut prototypes or a soft tool.
- Give annual volume, lifetime volume and packaging (bulk, reel, tray); they set the die class and the press.
- Settle die ownership, maintenance and storage in the purchase order.
Frequently asked questions
- What is the difference between progressive die and transfer die stamping?
- In a progressive die the part stays attached to the strip and is carried from station to station by the feed; in a transfer press the blank is cut free first and mechanical fingers move it between stations. Progressive is faster and cheaper for small and medium parts; transfer handles larger parts, deep draws and forms that need the part free of the strip.
- How much does a progressive die cost?
- Most run $30,000-150,000; large, carbide-section or in-die-assembly tools reach $250,000 and beyond. Design, tryout, first-article inspection and PPAP are usually quoted with the tool. The buyer normally owns the die and the stamper stores and maintains it.
- What volume is needed for progressive die stamping?
- The die pays off against the per-part savings over simpler methods. Most stampers look for 50,000-100,000 pieces a year, or 25,000 with a multi-year life; connector and terminal dies run in the millions. Below 10,000 a year, single-station tooling or laser cutting and bending is usually cheaper.
- Who owns the stamping die?
- Usually the buyer pays for and owns the die and the stamper keeps and maintains it; the purchase order should say so, along with who pays for sharpening and repair and what happens to the die if the work moves. Some stampers amortize the die into the piece price instead, in which case they own it.
