Metal stamping: progressive dies, deep draw and the tooling decision

Stamping is priced after engineering review, because the price depends on a tool that must be designed first. Sheet metal fabrication (laser cutting and press braking, with no dedicated tooling) is ordered online, and a specialist prices it within 24 hours on business days. For most of a product's life it is the right route.

A stamped part is usually a bracket, a shield, a busbar, a contact or a shallow housing inside a larger product. Our engineers design it with the rest of the product: the board, the enclosure and the assembly order. Through the demo build, EVT and DVT, the part is fabricated, so a change costs a new program and not a new tool. The die is designed after DVT closes the design. Before that, a DFM review checks the stamped geometry: bend radii against the material, hole-to-edge distances, burr direction, and the features a die can form in one stroke.

The review also answers the volume question with numbers from your part. You see the tooling cost, the per-part cost and the break-even quantity. The die is built in the in-house tool and die shop, and parts run on presses from 30–1000 t. Tooling you pay for belongs to you, and you may move it to another factory. Stamped parts can go into box build and test in the Shenzhen factory, next to the boards and housings of the same product.

Electrical parts need extra care. A busbar or a contact carries current, so its thickness, its plating and the burr on its edge all affect heat and contact resistance. A shield must close around a board area without touching parts on it. The stamped part is checked against the board layout as well as the drawing, and the DFM review is repeated before tooling so the last board change is in the die. For a battery pack, a charger or an EV part, the stamped metal is part of the power path, and the review treats it that way.

There is no single number. The crossover is where the tooling cost divided by your annual quantity falls below the per-part saving, and both sides depend on the part. A simple flat blank has a cheap tool and a small saving. A deep-drawn shell has an expensive tool and a large one.

What holds for every part is the shape of the decision, and our engineers put both costs in front of you before you choose. Fabricate while the design is moving and volumes are uncertain, because a fabricated part absorbs a revision for the cost of a new program. A stamped part absorbs it for the cost of a new tool. Tool up when the design has stopped changing and the forecast is firm. If the forecast is uncertain, a single-station tool for the highest-volume part is often a sensible first step.

A progressive die does several operations at successive stations as a metal strip moves through it: punching at one, forming at the next, cutting free at the last. One press stroke makes one finished part. Stamped parts are then cheap at volume and the tool is expensive, because every station is designed and proven together.

You need one when the part has more than one or two operations and the volume justifies combining them. For a simple blank, a single-station tool is often enough. This is one of the first answers a stamping review gives, because it changes the tooling cost more than any other decision. The stamping design guide explains die types and tolerances.

The fabricated route. A laser-cut and press-braked version of a stamped part is close enough for most testing, needs no tooling, and can be reissued the same day the drawing changes. You declare it as a flat cut part, a bent part, a welded part or a sheet-metal assembly, at any quantity from one.

Then tool up from a validated design. In our stage path, that usually means fabricated parts through the demo build, EVT and DVT, and the die after DVT closes the design. Order the bent version on the sheet metal route now, and send the same drawing for a stamping review when the forecast is firm. Our DFM review in the design phase plans that change-over from the start.