Progressive die stamping of phosphor bronze spring contacts, terminals and relay blades — dies designed and built in our own tool room, run on 21 presses from 25 to 110 tons at up to 300 SPM, with ±0.005 mm held on piloted features.
Fast Engineering ResponseNDA ProtectedSTEP / IGES / X_T / DWG
Trusted Tier-1 & OEM Standards:
PARTS WE STAMP
Phosphor bronze is specified where a part has to carry current and keep pushing back for millions of cycles. These four families cover most of the work here, and each one carries a different die approach, plating route and fatigue check.
Terminals, pins, receptacle bodies and crimp barrels from C51000 and C51100 strip. Tin content at 4–5% keeps the alloy formable enough for closed-barrel and box-style terminals while still holding contact force after crimping. Progressive dies carry piercing, forming and cut-off in one pass, and pre-plated strip is the usual route so the contact zone is never handled after forming.
Contact fingers, wiper springs, battery and socket contacts — the parts that justify the material. Spring temper strip is formed and coined in the die, with the bend radius kept inside what the temper will take, so the finger delivers the force the drawing asks for at its rated deflection instead of taking a set after the first few hundred cycles.
Relay arms, fuse clips, switch blades and contact bridges where conductivity and spring load meet in the same part. Roughly 15% IACS is the industry number for phosphor bronze — well below copper, and the reason a design puts phosphor bronze where the spring lives and copper where the current bulk travels, rather than asking one alloy to do both.
Small diaphragms, corrugated bellows, instrument hairsprings and stamped washers — thin gauges where the fatigue limit matters more than strength. These run from annealed stock when the form needs ductility, from spring temper when the part is a spring from the start, and the die is built for the temper named on the order.
INSIDE THE PLANT
Real equipment and inspection floor from our Dongguan plant — 25–110T high-speed presses, in-house tool room, and a CMM lab running first-article inspection on every program.
WHERE PHOSPHOR BRONZE GOES WRONG
Phosphor bronze is a spring alloy and it behaves like one in the die: it springs back, it cracks when pushed past its radius, and it relaxes if the forming stress is wrong. These are the four failures we design out before the first coil.
01
The Challenge
Spring temper phosphor bronze returns most of what you bend into it. A 90° form without compensation comes out at 80° and keeps moving as the temper drifts from coil to coil, so an uncompensated die produces parts that pass the first article and fail the tenth thousand.
Our Solution
Bend stations are modelled for overbend from the temper on the purchase order, then trimmed against real production coil, not a sample. Coining or a restrike station sets the final angle where the drawing is tight, and formed angles are released only after a first-article CMM report on the actual lot.
02
The Challenge
Phosphor bronze holds force better than brass, but it still relaxes. Run the bend at a working stress near yield, hold the part at reflow or in a warm enclosure, and contact force falls away over the service life. The failure shows up as intermittent contact years later, not as a dimensional reject at the press.
Our Solution
Bend radius and free length are sized so the working stress stays inside the elastic range for the temper quoted, and higher-tin grades go in when the force target is aggressive. On programs where the customer reflows the part, samples are aged through their profile and contact force is measured before release.
03
The Challenge
C52100 and C52400 buy strength with tin, and they pay for it at the bend line. Bend along the rolling direction, push the inside radius under one strip thickness, or leave a sheared edge with a rough break, and the outside fibre cracks — sometimes in the die, sometimes in the customer's hands during assembly.
Our Solution
Layouts put the bend across the rolling direction, keep the inside radius at one thickness or more on the high-tin grades, and hold die clearance per station so the sheared edge is clean before it is bent. Bends that close to a trimmed edge get moved or relieved at DFM, and edges are checked optically on first article.
04
The Challenge
Tin and silver pre-plate on phosphor bronze is thin and soft. Every stripper rub, pilot scrape and tumbling pass shows up as a bare patch on the contact face, and the alloy itself wears tool steel faster than brass does because the tin content makes it abrasive at the shear edge.
Our Solution
Dies for pre-plated strip get gentler entry, radiused pilots, relieved strippers and no post-stamp tumbling; parts leave the press reel-to-reel so nothing touches the plated face. Insert material and coating are chosen for the abrasive wear, punches are sharpened on counted strokes, and strip lubrication is matched to the surface.
HOW WE STAMP IT
Values we quote and inspect against on phosphor bronze work. Nothing here is a marketing range — if the press cannot hold it, it is not on the list.
| Specification Parameter | What We Hold | How It Is Controlled |
|---|---|---|
| Strip thickness | 0.05–3.0 mm | Mill certificate plus in-process thickness check at the press |
| Positional tolerance | ±0.005 mm on piloted features, ±0.01 mm on formed features | First-article CMM at 0.001 mm resolution, SPC in production |
| Stamping speed | up to 300 SPM | Thin contacts on high-speed frames, heavy strip on larger presses |
| Press fleet | 21 presses, 25–110 tons | Press matched to the part, with tonnage margin left for coining |
| Dies | 100% designed and built in-house | 30 machining machines behind the tool room |
| Quality system | ISO 9001:2015 · ISO 14001:2015 · IATF 16949:2016 | PPAP, mill certificates, lot traceability |
| Inspection | 20 inspection stations | CMM, optical and profile, in-line CCD on critical features |
| Plating | tin, nickel, silver, gold | Pre-plate on coil or post-plate through qualified finishers, incoming inspection in-house |
Progressive die design, machining and assembly under one roof — springback, burr and die wear on phosphor bronze are solved here, not on the press.
Thin spring contacts on the high-speed frames at up to 300 SPM; heavier strip from 1.5 to 3.0 mm on the larger presses in the fleet.
First-article CMM at 0.001 mm resolution, optical and profile checks for edges and radii, in-line CCD on the features the drawing controls.
Tin, nickel, silver and gold, either pre-plated on coil before stamping or post-plated through qualified finishers with incoming inspection kept in-house.
From Drawing to Production
Grade, temper, bend radii, spring direction, burr side and plating route settled before the die is cut — including whether the part should be phosphor bronze at all.
Progressive layout with piercing, forming, coining and restrike stations combined; die machined and assembled in our own tool room.
Run on the production coil, formed angles and contact force verified, PPAP documentation raised before the run is released.
Counted-stroke punch maintenance, in-line CCD on critical features, SPC on the dimensions and angles the drawing controls.
STRIP AND SUPPLY
We are a stamper, not a metal distributor — we do not sell phosphor bronze. We choose the temper and surface form the part needs, then quote it as material plus conversion. Precision phosphor bronze strip is bought to a temper and a thickness band rather than a grade name alone, because both move the spring rate.
Spring temper, quarter-hard, half-hard and annealed all run here, and the choice is a design decision, not a price decision. Annealed strip takes deep forms and tight radii but delivers no spring of its own; spring temper arrives pre-stressed and holds force, and it will not tolerate the same radii. A temper change is a die change.
Mill finish, pre-tinned, pre-nickel and selectively silvered strip are all workable. Pre-plate removes a post-stamping plating step and the handling damage that comes with it, but it limits the die to gentler entry and rules out tumbling. Post-plating gives more freedom on zone and thickness at the cost of one more process and one more inspection gate.
Either you supply coil to your own specification, or we procure the grade, temper, width and surface you name and quote material plus conversion with the mill certificate on file. If the grade is still open, we recommend between C51000, C51100, C51900, C52100 and C52400 before the die is cut.
Grades we run
BEFORE YOU SEND THE DRAWING
Eight checks worth making on a phosphor bronze drawing before tooling — the ones that decide whether the spring holds its force or relaxes in the field.
INDUSTRY CASES
Oct 20 · 1 min read
A fixture maker for highway lighting was getting its spring contacts loose in bags. Bulks arrived mixed orientation, operators wasted time singling them out, and a…
Oct 20 · 1 min read
An automotive lighting assembly plant runs a kanban card system with its stamping suppliers: a card goes out, a reel comes back, no forecasts, no warehousing. When…
Oct 20 · 1 min read
An appliance timer control builder was staging two suppliers: brass springs from one, silver contact rivets from another, and a manual riveting cell of its own. At…
ORDERING & FAQ
From drawing to delivered parts: a four-step path with engineering review at the front and 100% dimensional inspection at the back — then the questions buyers ask us most.
Step 1
Submit CAD & Specs
Send 2D/3D drawings (STEP, DWG, PDF) with quantity, material, and tolerance requirements.
Step 2
DFM Feedback & Quotation
Our engineering team conducts DFM analysis and follows up with a competitive quote after the review.
Step 3
Precision Manufacturing
High-speed progressive die stamping, secondary forming, finishing, and surface treatment per your specifications.
Step 4
100% QC & Express Shipping
100% dimensional inspection, anti-corrosion packaging, and global express delivery.
Either. We are a stamper, not a metal distributor — we do not sell phosphor bronze. You can supply coil to your own specification, or we procure the grade, temper, width and surface you name and quote material plus conversion.
C51000, C51100, C51900, C52100 and C52400 cover most of the work here — 5% tin through 8% and 10% tin where the spring load is higher. If the drawing names another grade, send the spec and we confirm stampability before quoting.
0.05 mm at the thin end of our range, 3.0 mm at the heavy end. Thin spring contacts run on the high-speed presses and heavier strip runs on the larger presses in the fleet, with the die built for the gauge the part actually sees.
Yes, and it is the usual route for contacts. Pre-plate keeps the finish on the contact zone only and removes a barrel-plating step, but the die has to be built for gentler entry and the parts cannot be tumbled afterwards.
±0.005 mm on piloted positional features, verified on a CMM at first article, and ±0.01 mm on formed features after springback compensation. Tighter formed angles are possible but depend on bend count and temper, so they are agreed at DFM.
Brass is cheaper and fine for light force at low cycle counts. Phosphor bronze is the general spring answer at about 15% IACS. Beryllium copper C17200 takes over when spring force or temperature is beyond what tin-bronze holds, at several times the material cost.
Ready to Start Your Precision Stamping Program?
Send your drawing today — engineering runs a free DFM review and detailed pricing follows the review.
100% Confidential | NDA Protected | 24H Response
