Brass stamping parts sit at the intersection of two properties that rarely coexist in one material: electrical conductivity high enough for a current-carrying contact, and formability high enough to be blanked, bent and coined at high speed. That combination is why brass remains the default choice for connector terminals, contact springs, shields and decorative hardware even after a century of alloy development — and why the specification details matter more than buyers expect.
This guide covers what to specify when you source custom brass stamping parts: which grade to call out, the thickness and tolerance envelope, how plating changes both dimensions and performance, and the design rules that keep a progressive die running at rate. It assumes you already know the part needs to be stamped; if you are still choosing between processes, our comparison of stamping or CNC for your part is the place to start.
Why brass is stamped rather than machined
Brass work-hardens slowly, has low yield relative to stainless, and holds a clean edge through blanking. In a progressive die, a brass terminal can be blanked, pierced, formed and coined in a single strip pass at hundreds of strokes per minute, with no cutting fluid contamination and minimal burr. Machining the same part from bar or plate consumes far more material and takes orders of magnitude longer per piece.
The economic crossover is familiar: below roughly 1,000 pieces, or when the part has three-dimensional features a die cannot produce, brass CNC machining is usually cheaper and faster. Above that, with a stable design and a flat or simply formed geometry, brass stamping wins decisively. Most connector and terminal work sits firmly in the second category.
Brass grades for stamping
| Grade (UNS / common) | Nominal composition | Formability | Typical stamped parts |
|---|---|---|---|
| C26000 (cartridge brass, 70/30) | Cu 70, Zn 30 | Excellent | Deep-drawn shells, terminals, contact blanks |
| C26800 / H65 (yellow brass) | Cu 65, Zn 35 | Excellent | Contacts, brackets, decorative plates |
| C27200 | Cu 63, Zn 37 | Very good | Washers, spacers, spring clips |
| C28000 (Muntz metal) | Cu 60, Zn 40 | Good | Structural brackets, heavier stampings |
| C23000 (red brass) | Cu 85, Zn 15 | Excellent | Corrosion-resistant washers, plumbing stampings |
| C22000 (commercial bronze) | Cu 90, Zn 10 | Excellent | Architectural and marine hardware |
Free-cutting brass (C36000) appears often in machining but rarely in stamping — its lead content improves chip breaking, not formability, and it is prone to cracking in tight bends. If your drawing says "brass" and nothing else, ask for the UNS number; the difference between C26000 and C28000 changes both the bend radius and the achievable draw depth.
Two adjacent alloys are worth considering before you finalise:
- Phosphor bronze (C51000, C51900) — better spring properties and fatigue life, lower conductivity. The right choice when the stamped part is a spring contact that must retain force over many cycles.
- Beryllium copper (C17200) — highest strength and the best spring behaviour of the copper alloys, at a significant material cost premium, and with handling controls during processing. Choose it when contact force and cycle life dominate the design.
What brass stamping parts we make
Typical parts that run through our presses include:
- Electrical terminals and connector contacts
- Contact springs, clips and retaining clips
- Flat, spring, tab and lock washers; spacers and shims
- Shielding cans and EMI contact plates
- Grounding plates, busbar tabs and earth plates
- Cosmetic front and cover plates, nameplates
- Connector shells and drawn housings
- Cable lugs and plumbing ferrules
Our precision stamping runs strip from 0.2 mm to 3.0 mm across progressive and compound dies, with the same cell also producing stainless steel and phosphor bronze stampings. The electroacoustic and consumer electronics sectors use the largest share of this work, followed by switchgear and automotive connector harnesses.
Thickness, tolerances and what drives them
| Parameter | Typical capability | Notes |
|---|---|---|
| Material thickness | 0.2–3.0 mm | Above 3 mm the process shifts to heavier press work with different dies |
| Blanked profile tolerance | ±0.05 mm standard | Tighter on selected features with a secondary operation |
| Pierced hole diameter | ±0.03–0.05 mm | Below 1 × thickness, plan for drilling |
| Hole-to-hole in one die station | ±0.03 mm | Best case: the relationship is set by the die, not by handling |
| Bend angle | ±1.0° typical | Brass springback is moderate; see below |
| Burr height | ≤0.05 mm achievable | Specify burr direction and maximum height on the drawing |
| Flatness | 0.05–0.15 mm per 25 mm | Thinner stock moves more |
Two things surprise buyers here. First, a relationship between two features made in the *same die station* is far more accurate than a relationship across stations, because the die itself becomes the gauge — the ±0.03 mm figure above is a die-controlled number, not a process-controlled one. Second, brass springback is real but modest: expect roughly 2–5 degrees depending on temper and bend ratio, which the die compensates for during tryout rather than during production.
Plating and surface finish
Brass tarnishes. Almost every stamped brass part gets a coating, and the coating selection is usually driven by one of three requirements: solderability, contact resistance, or appearance.
| Finish | Thickness | Why it is chosen | Dimensional effect |
|---|---|---|---|
| Tin (matte or bright) | 3–10 µm | Solderability, low cost, food-safe grades available | +6–20 µm on diameter |
| Nickel (electroless or electrolytic) | 3–15 µm | Wear resistance, barrier layer under gold | +6–30 µm on diameter |
| Silver | 2–8 µm | Lowest contact resistance, high-current contacts | +4–16 µm on diameter; tarnishes |
| Gold over nickel | 0.5–2 µm gold | Corrosion-free contact surface for signal connectors | +1–4 µm; nickel underlayer dominates |
| Zinc | 5–12 µm | Low-cost corrosion protection for non-electrical parts | +10–24 µm on diameter |
| Passivation / anti-tarnish | Negligible | Keeps cosmetic brass bright without dimensional change | None |
| Polishing / brushing | Removes material | Decorative hardware, nameplates | −0.01 to −0.03 mm |
Two specification points follow directly. State the inspection state — a Ø2.00 ±0.05 mm hole with 8 µm of nickel per side measures Ø1.98 mm before plating, so "before plating" and "after plating" give different answers for the same callout. And specify the plating on the *functional* surface only where function requires it; selective plating (strip, spot or brush) costs more per part but removes a masking step and often a rejection mode.
The interaction between plating and the rest of the finishing sequence is covered in more depth in our CNC parts finishing guide, which uses the same dimensional-allowance logic.
Design rules for a stable progressive die
- Keep the part flat or simply formed. Every extra forming stage adds a die station, and every station adds cost and variation.
- Hole diameter at least equal to material thickness, ideally 1.5 × thickness. Smaller holes mean fragile punches and frequent breakage.
- Minimum bridge between holes and between hole and edge: at least 1 × thickness, 2 × thickness preferred. Thin bridges deflect and cause slug pulling.
- Bend radius: at least 0.5 × thickness for C26000, larger for harder tempers. Brass is forgiving, but a sharp inside corner on a spring-temper part will crack.
- Specify burr direction and maximum height. Burr orientation affects assembly seating and, on contacts, the mating force.
- Grain direction matters for springs. A stamped spring contact should have its bend axis perpendicular to the rolling grain, or it will take a permanent set early.
- Carrier and tab location are the supplier's call, not the designer's. Define the finished part geometry and let the die designer place the carrier; specifying the strip layout usually increases tooling cost.
- Provide a 3D model plus a dimensioned 2D drawing. The model sets the geometry, the drawing sets the tolerances, plating, burr and inspection state.
If you want those checks run before you commit to tooling, that is exactly what a DFM analysis before quoting produces, and it applies to sheet metal and custom sheet metal fabrication parts in the same way.
Brass Progressive Stamping: Why the Alloy Runs Differently
Brass progressive stamping is easier than steel in some respects and harder in others, and the differences are all traceable to the alloy rather than to the tool. Brass is significantly more ductile than carbon steel — cartridge brass (C26000, roughly 70/30 copper-zinc) elongates well beyond 40% in the annealed condition — so it tolerates deep draws, tight bends and multiple forming stations in one progressive tool that would crack mild steel. It also work-hardens more slowly, which is why a long strip layout can carry more forming stations before an anneal is needed.
The complication is that the brass you machine is not the brass you stamp. Free-cutting grades such as C36000 and the forging brass CuZn39Pb3 (C3771) contain lead specifically to break chips, and that lead makes them hot-short and comparatively brittle in deep forming. They are the right choice for CNC machined brass parts and the wrong choice for a drawn or heavily formed progressive part. Stamping layouts should specify unleaded grades — C26000, C2680, C2720 or the lower-zinc red brass C2300 — and if the part is subsequently machined, that grade choice needs to be agreed before the tool is designed, because switching later changes cutting forces, springback and tool clearance together.
Two process settings follow. Die clearance on brass should be tighter than on steel: brass is soft, and too much clearance smears rather than shears, producing a soft rolled burr that is difficult to remove without rounding the edge. And springback, while lower than steel, is not zero — expect roughly half to one and a half degrees depending on bend radius-to-thickness ratio, which is why a first-article bend angle check on production material matters more than a simulation. Both are covered in the brass grades discussion above, and both are cheaper to settle at DFM review than after the die is ground.
Tooling, cost and lead time
Progressive die tooling for a small brass terminal is a meaningful one-off cost, but at volume it amortises to a small fraction of the unit price. The variables that move the quote most are: number of die stations, tolerances on pierced features, plating type and whether it is selective, and annual volume (which sets how fast the tooling pays back and whether a single-cavity or multi-cavity die is right).
Expect tooling lead time measured in weeks and production measured in days once the die is qualified. First article samples should be approved before the run starts; for regulated or automotive programmes, ask for the dimensional report and material certificate with the FAI rather than after it.
Getting a quote
The fastest way to an accurate number is a clean package: 3D model, dimensioned 2D drawing, UNS material grade, temper, plating specification with the inspection state, annual volume and target delivery schedule. With those, most quotes go out within 24 hours.
Ruijin runs precision stamping alongside CNC turning, milling, five-axis machining, sheet metal fabrication and surface treatment in one Dongguan facility, so a stamped brass contact that needs a machined housing or a plated finish stays in one process chain. Send your drawings to request a quote or see the precision metal stamping page for the full process envelope.
FAQ
What CNC machining services does Ruijin CNC offer?
Ruijin CNC provides CNC turning, CNC milling (3-axis and 4-axis), 5-axis CNC machining, sheet metal fabrication, metal stamping, and surface treatment including anodizing, plating and powder coating.
What tolerances and certifications does Ruijin CNC hold?
We hold tight tolerances down to ±0.01mm across all processes, and are certified to IATF 16949, ISO 9001 and ISO 13485.
What is the minimum order quantity and lead time?
We accept prototypes from 1 piece with no strict MOQ, provide free DFM review, and return a quote within 24 hours of receiving your CAD drawing and requirements.
How do I get a quote from Ruijin CNC?
Send your STEP file and drawing to gongtianbao@xhlmarketing.com or via WhatsApp +86 17620300785. We reply with a DFM review and a firm quote within 24 hours.